World J Clin Cases. 2015 Mar 16; 3(3):245-64. doi: 10.12998/wjcc.v3.i3.245.
Fluoroscopy guided percutaneous renal access in prone position
Gyanendra R Sharma 1, Pankaj N Maheshwari 1, Anshu G Sharma 1, Rita P Maheshwari 1, Ritwik S Heda 1, Sakshi P Maheshwari 1
Affiliations expand
PMID: 25789297
PMCID: PMC4360496
DOI: 10.12998/wjcc.v3.i3.245
Free PMC article
Fluoroscopically guided prone-position percutaneous renal pathway establishment
Percutaneous nephrolithotomy is a very common procedure used to treat kidney stone disease. Establishing a good channel is the first and probably the most critical step in this process. A good passage is the gateway to success. However, this critical step has the steepest learning curve because in a fluoroscopy-guided visit, it involves visualizing the three-dimensional anatomy on a two-dimensional fluoroscopy screen. This review describes the anatomical basis of renal pathways. It provides a literature review of all aspects of the percutaneous renal pathway, as well as the progress that has been made in this area over the years. This article describes a technique that uses simple mathematical principles to determine the site, angle, and depth of skin piercing. It also reviews common problems faced during puncture and dilation and describes ways to overcome them. The purpose of this article is to provide readers with a step-by-step guide to the percutaneous renal pathway.
Core Tip: This article reviews various fluoroscopy-guided renal pathway techniques. It provides an in-depth description of the technique with the aim of allowing the urologist to guide the procedure step by step. It gives the anatomical basis of the percutaneous renal pathway and describes the skin site, angle, and depth of the puncture to be determined. It also describes the difficulties faced and makes recommendations to prevent and overcome them.
Percutaneous nephrolithotomy was first reported by Rupel and Brown in 1941. Goodwin et al. 1955 described percutaneous trocar nephrostomy in hydronephrosis kidneys. Especially after the description of Fernstrom and Johansson in 1976, the technology became popular. Improvements in urological equipment and advances in technology have led to percutaneous nephrolithotomy (PCNL) being accepted as the gold standard for the treatment of patients with nephrolithiasis larger than 20 mm in diameter [6]. Its popularity and acceptance among urologists and patients is largely due to the fact that it is minimally invasive and associated with low morbidity. Initially, the procedure was performed in the prone position using fluoroscopic guidance only. However, in the last few decades, ultrasonography alone or in conjunction with fluoroscopy has been used for percutaneous renal access. Various modifications to the patient's position are also described to overcome some of the limitations and drawbacks of percutaneous renal access in the prone position. Despite these changes, fluoroscopy-guided prone access remains the most commonly used technique for PCNL. The prone position is associated with a significantly shorter nephrostomy tube length and more potential sites of entry, which may improve the convenience and safety of percutaneous renal access. In European countries, urologists establish their own percutaneous renal access, but in the United States, access is usually performed by interventional radiologists. Studies have shown that radiologists who perform renal access have a lower rate of free stones and a higher rate of complications. Despite these facts and the documented safety and efficacy of percutaneous renal access obtained by urologists, only 11% of urologists who undergo PCNL are able to achieve access. This low success rate may be attributed to a lack of skills. This may be due to the difficulty of visualizing and mind-absorbing the three-dimensional anatomy of the pelvic system on a two-dimensional fluoroscopic screen. The aim of this review was to describe aspects of fluoroscopy-guided prone percutaneous renal access techniques. The authors have tried to provide a step-by-step guide to various aspects of this technique. Finally, the authors describe their technique in detail and the rationale behind it.
Ureteral catheter placement
At the beginning of the procedure, a 5 Fr or 6 Fr ureteral catheter is inserted into the collecting system using a rigid cystoscope (the patient is in the lithotomy position) or a flexible cystoscope (the patient is prone to the patient). This is used to instill contrast to make the system opaque. It can also be used to flush saline to dilate the system, to flush small gravel during lithotripsy, and sometimes to insert a double J (DJ) stent through a slipline at the end of surgery. The Foley catheter also passes through one side of the ureteral catheter. The two catheters are secured to each other to prevent inadvertent slippage out of the ureteral catheter.
Prone position
This is an important procedure that can cause serious harm to the patient if not done properly. The ideal approach is to have the patient supine with a separate cart next to the operating table, transfer the patient in the supine position to the side cart, remove the monitoring device, and then have the patient prone on the operating table and immediately attach the disengaged or removed device. These procedures should be performed by adequate staff, with appropriate coordination between the anesthesiologist who manages the airway, endotracheal tube, and neck and the staff who manage the chest and trunk. Although cervical spine injuries are rare when in the prone position under anesthesia, excessive flexion and hyperextension have been reported during prolonged surgery. Patients with cervical spondylosis, Down syndrome, or rheumatoid arthritis or myelopathy syndrome are at greatest risk. Postoperative vision loss is an uncommon condition (0.2% of spinal surgeries in one review), but a serious complication of prone surgery. The ability to maintain good ventilation and hemodynamic stability throughout the procedure is a challenge for anesthesiologists. For healthy, adequately anesthetized patients, these may not be clinically relevant; However, for those with associated comorbidities, this can be very unstable. Therefore, whether the surgery is performed under general or regional anesthesia, constant vigilant monitoring is essential during the procedure. Anesthesia for PCNL cannot and should not be taken lightly.
Patient position
Care should be taken to ensure that pressure points are properly filled and that the limbs should be positioned in such a way as to avoid overstretching, especially the joints. This will prevent accidental injuries and nerve stretching. The thoracic and abdominal support ensures greater lung capacity in the prone position compared with the supine position [18]. Once positioned, the flanks are ready and the unsanitized areas are covered with curtains (Figure 1). Figure 1: Patient's position.
The arrangement of the trolley
Figure 2: Arrangement of the trolley. A: Arrangement of lower pole puncture; B: Arrangement of the upper pole puncture. As shown in Fig. This helps to clearly see the fluoroscopic and endoscopic camera monitors (Figure 2).
Contrast media
Contrast is infused through the ureteral catheter to make the renal pelvis system opaque and to identify the calyces that should be punctured. The contrast ratio should be diluted 1:3. The ureteral catheter, if placed in the upper rod, should be pulled down a little so that it is in the renal pelvis. This helps to fill all the cups correctly. The dye should be instilled slowly to prevent extravasation. There should be continuous fluoroscopy monitoring so that it can be seen which calamities were filled earlier and which were late, which can help identify the posterior calamities.
Puncture options?
Establishing appropriate percutaneous renal pathways is the gateway to success or disaster in PCNL. Planning this requires a basic understanding of anatomy. The kidneys are located in the posterior abdominal wall against the psoas muscle, and its longitudinal axis runs obliquely parallel to the psoas major muscle, at an angle of 13° to 30° to the midline. In addition, because the psoas muscle is tapered in shape, the kidneys have a dorsal tilt on their longitudinal axis, with the upper pole being more medial and posterior than the inferior pole. Since the hilar region rotates anteriorly on the psoas muscle, the kidneys rotate posteriorly about 30°, so the lateral side of the kidney is posterior medially. The kidneys are also tilted 30°-50° behind the frontal (coronal) plane, with the lower pole before the upper pole. In the prone position, the renal pelvis tends to fall anteriorly on the psoas muscles; Thus, the lower pole, renal pelvis, and proximal ureters are more anterior than the upper pole. Calyceal drainage at the poles of the kidneys is also important. Sampaio found that in 98.6% of the cases he studied, the upper pole was drained by only one midline calyceal funibulum; In 58% of cases, the lower pole was drained by two rows of paired calyceses, in 42% of cases by a midline excantium calyce, and in 96% of cases, the midpole was drained by two rows (anterior-posterior) of paired calyxes. This has important implications for percutaneous renal pathways, as endoscopically access to the polar region drained by a single infundibum, which usually has a suitable diameter, rather than the polar region drained by paired calyceses. He also found that for best access to the pelvic-ureteral junction (PUJ), a rod with the calyces at an angle of 90° or more to the PUJ should be chosen. The puncture program begins preoperatively with appropriate evaluation of the imaging study. Traditionally, intravenous urography has been used to collect functional and anatomical assessments of the system. Nowadays, coronal reconstructive CT urography is becoming increasingly popular [25]. The advantages of CT scans over intravenous urography are the ability to assess the spatial relationship of the kidney relative to the stone, to depict the calyceal anatomy in 3D format to select the site of entry, to assess the risk of pleural or intestinal injury, and even to predict the successful subcostal fluoroscopic access for upper pole puncture. 7. Preoperative testing of splenomegaly or the presence of a postrenal colon can avoid serious complications associated with catheter placement. These advantages are offset by the slightly higher cost in developing countries and the lack of widespread availability of multiplanar CT scans. Regardless of which imaging modality is used, the urologist must select a puncture rod that provides the straightest path along the stone axis and provides maximum or complete stone clearance. A useful aid to making this decision is to make an "outline-o-gram". As shown in Figure 3A, there is a complete antler calculus. The "outline-o-gram"3B shown in the figure indicates that most of the stones can be removed by inferior pole puncture. Midpole stones require a separate puncture or the use of a flexible nephroscope. Thus, the "outline-o-gram" can be used as a guide to determine the pole to be pierced and also to decide if a multi-hole is required.
图 3大纲-o-gram。 A:KUB 显示左鹿角形演算;B:Outline-o-gram 表明大部分结石可以通过下部穿刺清除,残留碎片可能需要单独穿刺。
Which one to pierce?
The literature clearly indicates that for safe and uncomplicated entry [20, 21], posterior calyces should always be punctured.
Why is the post-puncture group calyx?
A good understanding of the anatomy of the kidneys provides an answer to this question. The blood supply to the kidneys comes from the renal arteries, which are divided into anterior and posterior branches. These are further divided into segmental arteries that supply specific areas of the kidney, as shown in Figure 4. Since these arteries are terminal arteries, there is a relatively avascular area between these two branches called the Brodel bloodless incision line. In this area, the likelihood of bleeding complications is minimal. Due to the rotation of the kidneys, the posterior calyces are usually oriented in such a way that the long axis points to the Brodel line. Thus, puncture of the posterior calyces will pass through this relatively avascular area [30]. Also, since the patient is prone on his stomach, it will provide a direct path to the renal pelvis. If the anterior calyces are punctured, there is an increased risk of bleeding because it does not cross the Brodel line. Passes through more parenchyma to reach the calyceses, resulting in more kidney damage. In addition, due to the acute angle between the puncture line and the infundibulum part, access to the renal pelvis will become difficult, associated with greater torque, increasing bleeding and damage to the renal parenchyma. Figure 4
Renal artery blood supply.
Calyceal orientation – which calyceus is the posterior group calyces?
The renal papillae drain into the small calyces and may be simple or compound. There are three drainage areas: upper, middle and lower rods. The compound calyx is dominated by the upper pole, the lower pole is common, and the middle is very rare. The investigators have tried to distinguish between anterior or posterior calyx based only on the medial or lateral orientation seen on the IVU. The anatomical references available in this regard are contradictory, confusing, and incomplete. In 1901, Brodel studied a corrosion model of 70 cadaveric kidneys. He depicted the anterior calypse as medial and the posterior calyces as lateral. Hodson's 1972 description was the opposite, with the anterior calyces located lateral and the posterior calyces medial [32]. Then, in 1984, Kaye and Reinke [33] measured the calyceal angle from axial CT images. They concluded that 69% of the right kidney had the Brodel pattern, while 70% of the left kidney had the Hodson pattern[33]. Sampaio et al. [34, 35] studied 140 inner castings and found that 28% of the anterior calyces were lateral and 19% of the posterior calyces were lateral, and in 53% of the inner castings, the anterior and posterior calyces had different positions, overlapping or alternating distribution. In one region, the outermost is the anterior calyce, while in the other, the outermost is the posterior calyce) [34, 35]. He found that the direction of the calyces depended on the area. The typical anterior and posterior calyx patterns are found only in the middle pole [22]. The lower pole has this arrangement only 58% of the time, while the upper pole almost uniformly has a composite calyx system [22]. This means that in the lower and upper poles, the calyces are mainly oriented in the direction of their respective poles. This has been further investigated by 3D CT rendering, which also looks at the major planes of the calyceal group. Miller et al. [17] found that at the upper pole, the predominant plane of the upper pole calyces is medial/lateral and is generally neutral relative to the anteroposterior axis of the kidney. Since the upper pole is more posterior in the prone position, access through any calyx provides a working passage parallel to the longitudinal axis of the kidney. This would mean entering through an angle that allows the rigid apparatus to reach most of the calyces in the kidneys [17]. However, it is preferable to puncture the outermost calyces at the upper pole because puncture of the medial calyces is associated with a significant risk of posterior segment artery injury [36]. Eisner et al. [37] investigated the inferior pole anatomy by CT scan of 101 units. They found that if there were two calyces at the lower pole, the medial calyx was anterior in 95% of the units, while the lateral calyx was posterior in 93% of the units. If there are 3 calyces at the lower pole, the medialmost calyces are anterior in 93 units. In such nephrons, from the lateral to the innermost, i.e., the second calyx is posterior in 70% of the units, while the outermost calyces are anterior in 71% of the units. In 31% of cases, there is no true calyces in the posterior. Of these kidneys, although both calyces are in front, one of them has less of a front than the other. Their study showed that the innermost calyces on 2D imaging were anteriorly facing 94% of the time, regardless of the number of lower pole calyceses. They suggested that the calyx, just outside the medial calyce, the second calyce, was statistically most likely to be posterior, with the calycea in the most posterior position.
How to identify the posterior calyces on fluoroscopy?
Due to the unreliability of anteroposterior radiographs, the optimal posterior calyces for entry cannot be determined, so additional manipulation is required. When the patient is in the prone position, the diluted contrast medium will first fill the dependent anterior cup at the time of instillation. As a result, the posterior goblet will be filled later and will appear less dense [21]. Injecting 5 to 10 mL of air through the ureteral catheter can also help identify the posterior calyces, as air preferentially enters these calyces when the patient is prone . Although there are difficulties in identifying the posterior calyces, if these maneuvers are present, the movement of the C-arm can help identify the posterior calyx. In the prone position, the posterior lamp moves in the opposite direction to the image intensifier on the C-arm. If the arm C is rotated toward the surgeon, the posterior cup is removed and shortened. And vice versa, if the C-arm is rotated away from the surgeon, the back cup appears elongated. Thus, the laterally placed cup can be identified as posterior by removing the C-arm from the surgeon, and by moving the C-arm toward the surgeon, the posterior cup appears more inward and appears on [9].
Needles used for puncture
Punctures should be done using a diamond-tipped needle rather than an angle-tipped needle. The diamond-tipped needle has a symmetrical tip that exerts equal force in all directions of the tissue. Thus, the tissue is cut in the direction of movement of the needle tip. The oblique tip needle exerts an asymmetrical force, so the tissue is cut at an offset angle depending on the bevel angle, the flexibility of the needle, and the tissue characteristics [39]. The size of the needle used for puncture is a controversial issue. The options are either a 21-gauge pin (0.018-inch guidewire is allowed) or an 18-gauge pin (0.035-inch guidewire is allowed). The 18-gauge needle is harder but more traumatic. The 21-gauge needle is less traumatic but less stiff, so it does not adequately maintain the trajectory. In addition, the 0.018-inch guidewire that passes through the 21-gauge needle must be replaced with a standard 0.035-inch guidewire for subsequent tubing dilation. This requires an extra step, which increases the complexity of the procedure and increases the risk of losing access. Weighing the pros and cons of both, it is reasonable to use a 21-gauge needle when the surgeon is inexperienced or currently needs to minimize trauma.
What should be the trajectory of the needle?
The renal pelvis should not be punctured directly because of the very high risk of injury to the posterior renal pelvis vessels (arteries and/or veins). Sampaio's study has demonstrated beyond a shadow of a doubt that puncture of the infundibulum of the calyces is associated with a significant risk of massive bleeding in the interlobar vessels. There is an increased risk of the collecting system being penetrated and punctured. The risk of superior polar artery injury is greatest, and posterior segment artery injury may be caused by puncture of the upper pole excibular part, which is associated with the posterior surface of the upper excantium in 57% of cases. Damage to this artery can result in up to 50% loss of renal parenchyma as well as severe bleeding [30, 35]. The trajectory of the needle at the time of puncture should be aligned with the fornix and not the infundibulum (Figure 5). In other words, we should aim at the center of the calyces on the posterolateral side through the renal parenchyma. When puncture is performed through the fornix, arterial injury does not occur, and venous injury occurs in less than 8% of cases. Figure 5
The trajectory of the needle during the puncture.
Criteria for a good puncture
Percutaneous renal access through the calyces must meet five conditions to ensure safe access and avoid complications: (1) access should be performed from the posterolateral side; (2) the pathway should pass through the renal parenchyma; (3) The entrance should be towards the center of the posterolateral side of the calyx; (4) Due to these four conditions, the pathway should be towards the center of the renal pelvis; (5) The trajectory does not damage any major blood vessels.
Types of fluorescence-guided punctures
There are two types of fluoroscopy-guided puncture techniques – bull's-eye and triangulation. In addition to these two, a number of variants are described.
Bull'seye technology
It is also known as the needle-eye technique [20]. The target calyces are identified in the axial plane as an arm C of 0°. The C-arm is then rotated 30° towards the surgeon and the calyx to be punctured will appear on the fluoroscopic screen. A caudal tilt of 5° to 10° in the caudal direction of the lower pole or the cranial direction of the upper pole may require a rounded end when the calyces appear after the target [21]. Then mark the location on the skin covering the selected calyx and begin the puncture. The needle is advanced at the end of full expiration. It is seen as a bull'seye (as a dot) on a perspective screen. If you see the longitudinal part of the needle, it indicates that the trajectory is incorrect and needs to be adjusted accordingly. The C-arm can be rotated several degrees from the surgeon to get a correct perspective of the puncture depth. The needle will now be seen in the outline. It is then advanced to puncture the calyx. The free outflow of urine determines the location in the collection system [20, 21, 41, 42]. To minimize radiation to the opponent, the needle can be secured with a hemostat, sponge forceps, or a special radiolucent needle holder (Figure 6).
Figure 6 Bullseye appearance of a needle.
Modification of the bull's-eye technique
Bilen et al describe the use of an in-line laser pointer to guide the renal pathway in which the laser is attached within the receiving head region of the C-arm fluoroscopy unit. Ko et al describe a further modification using a laser positioning device mounted on a C-arm, in which the laser beam is continuously focused on the hub of the needle in order to maintain proper alignment during puncture without the use of fluoroscopy. This approach can reduce perspective exposure early in the learning curve. As experience increases, muscle memory leads to the maintenance of correct alignment. Triangulation Techniques Triangulation is a technique that uses two known reference points to locate a third unknown point. It is guided by a biplanar perspective. Arm C assesses the medial and lateral planes at 0°. Depth is assessed by rotating the C-arm 30° in the cranial or caudal direction. The target calyx is identified with a 0° C-arm. The puncture line is then aligned with the funnel section. When the C-arm is at 0°, the needle is introduced through the skin incision. Left and right, i.e., medial and mid adjustments, with the needle aligned with the calyce. Then rotate the C-arm 30° to perform the lower rod puncture toward the cephalic end and the upper puncture toward the foot end. Then orient the needle up and down, i.e., head and tail position, so that the direction is again towards the desired calyx. When making adjustments in one plane, it is necessary to maintain the orientation of the needle in the other plane. The needle is then advanced and the C-arm is tilted 30° to understand the depth and end-expiratory pause in breathing. After advancing the needle a few centimeters, move the C-arm to 0° to see that the trajectory of the needle is still properly aligned with the target calyx in the median and lateral planes. If necessary, the needle trajectory can be readjusted to maintain correct positioning. To minimize damage to the renal parenchyma, adjustment of the needle level should be performed when the needle is inserted outside the renal capsule, not at the time of needle insertion. The slight shaking of the needle resulting in an indentation of the desired calyx further indicates that the trajectory of the needle is correct. If the position of the needle in the medial-lateral and cephalic-caudal planes remains unchanged, the needle should enter the target calyce. In triangulation techniques, it is better to use an 18-gauge needle rather than a 21-gauge needle, as its stiffness provides better stability and helps to maintain the angle of entry .
Comparison of bull's eye and trigonometry
In the triangulation technique, the puncture is aligned along the calculus axis, i.e. with the funnel part. This reduces the need for rigid instruments to exert excessive torque on the renal parenchyma, which can lead to kidney damage and bleeding. Tepeler et al. compared the bull's-eye and triangular methods and found no difference in the duration of surgery, fluoroscopic screening, length of hospital stay, and blood transfusion rate. They found a slight decrease in hematocrit and complication rates in the group that entered by the bull's-eye technique compared to the triangulation technique. However, there was no statistically significant difference. The advantage of triangulation over the "eye of the needle" technique is that the needle cannot pass too deep because the depth of propulsion is continuously monitored [39]. In addition, triangulation alone met five criteria for successful puncture. The disadvantage of triangulation techniques is that it is difficult to maintain the medial-lateral and head-tail planes at the same time, as they are not monitored simultaneously like the "eye of the needle" technique. Performing this task requires complex visuospatial skills when using C-arm fluoroscopic devices, especially when novice surgeons [44]. It is at this moment that urologists need to make several attempts, and overuse fluoroscopy, especially for beginners. It is also the steepest aspect of the learning curve for urologists trained in percutaneous nephrolithotomy. Usually, during the learning curve, the problem is the depth assessment when the C-arm is in an inclined position. Whether the needle is on the surface or deep part of the calyces must be determined by the surgeon and adjusted accordingly [46]. The easiest way to determine this is to place another needle on the surface of the skin above the target calyx. If the calyces are between the two needles, the needle is deep and surface adjustment should be made. If the target calyx is below the two needles, the needle is superficial and should be adjusted in the direction of depth.
Modification of triangulation techniques
Several new methods and improvements have been described to improve access and reduce the learning curve for surgeons. Moose et al. [47] described a geometry for creating a coincident plane between the C-arm and the needle, each at the same angle as the target calyce, 20°-30°, but in opposite directions. For the inferior pole approach, the C-arm is rotated 30° from the vertical plane to the cephalad and the needle is advanced from the position of the distal end of the calyx and 30° from the vertical plane to the caudal side. For mid- and superior-pole calyx entry, arm C is rotated 20° away from the surgeon, and the needle is advanced from the position on the side of the calyx at a 20° angle from the vertical plane toward the surgeon. During the procedure, the C-arm remains fixed and the needle is advanced until the point of coincidence between the calyces and the tip of the needle is reached. However, this technique requires a plumb weight, a protractor, and a ruler to calculate and confirm the necessary measurements. In addition, it assumes that the angle of convergence is 30° at the lower pole and 20° at the other poles. This may not always be true, given the wide range of changes in kidney structure that occur with varying degrees of hydronephrosis. Lyazikos et al. described a technique that utilizes triangulation to target the calyces from a pre-selected puncture site. After the calculus is removed from the initial puncture site, the sheath is withdrawn and the puncture from the initial puncture site requires access to complete removal of additional calculus. Despite multiple entries through a single incision, a single nephrostomy tube can be left . These come from a single point, but in different directions. This does not reduce the chances of complications. In addition, attempts to manipulate the rigid nephroscope may increase the torque to the renal parenchyma, resulting in increased bleeding. Moselle et al. describe a computer-generated system that can be used to virtually project ultrasound nephrostomy onto fluoroscopic images. Therefore, the surgeon has the benefit of being able to preview the three-dimensional anatomy while performing the procedure, rather than the usual two-dimensional fluoroscopic image. While exciting, it requires a special system that is not normally available. Newer arms C, utilizing software to provide three-dimensional images, have also been used to obtain renal access in animal models. Robotic assistance for fluoroscopic percutaneous renal pathways has also been studied and is being evaluated. These future technologies have not yet gained widespread acceptance A study comparing robotic-assisted renal access with standard manual access showed that the time required for a robotic puncture to achieve puncture was shorter (10.4 minutes versus 15.1 minutes) despite the comparable average number of access attempts. However, there are 3 scenarios where the bot is unsuccessful and a switch to manual access is required [53]. Li et al. described a stereotactic positioning system with specially designed instruments]. It uses the Pythagorean principle of a right triangle to calculate the puncture depth. The puncture is then performed using a specially designed and patented instrument with a pre-calculated puncture depth and angle. The tubing is then dilated using the same instrument. The authors found that their technique was associated with higher efficiency, better stone clearance, and lower morbidity, which they attributed to higher puncture accuracy. When the puncture angle is less than 30°, the technique is found to be useless because the operator's buttocks get in the way. And the author generally chooses puncture points with the same vertical and horizontal distance, that is, 45 ° from the skin to the stone. This again makes the principle of puncture rather rigid, as changes in the anatomy of the renal pelvis may prevent adherence to this rigid principle. More recently, Hatipoglu et al. [Figure 55] described a single-plane access technique. The selected calyces are marked with clips. For inferior pole puncture, the needle is placed 1 cm below and medially to the 12th rib. The needle is placed at a 30° angle to the sagittal plane and points towards the desired calyx. If puncture fails, the needle is retracted approximately 1 cm inside the body and its angle of entry is adjusted and reinserted in the same vertical plane. For the middle and upper pole puncture, the needle is perpendicular to the spine and at an angle of nearly 30° horizontally to access the target middle and upper calyces to reach the pelvis and inferior pole. The authors propose that since the C-arm is fixed in the anteroposterior position, rotation is avoided and the surgical time required for puncture is shorter. However, there was no upper pole puncture in this study. In the initial learning curve, surgeons will find this technique difficult to master. In addition, the use of a pre-fixed puncture point on the skin for all inferior pole punctures and the guidance of the needle at a fixed angle of 30° to the sagittal plane may not always be the correct approach, especially given the variation in the position and orientation of the inferior pole.
Hybrid technology
The rationale holds that the three most important things to achieve a successful percutaneous renal puncture are the site of skin entry, the angle of entry, and the depth of puncture. Determining the correct skin puncture point is important in the triangulation technique, as skin puncture that is too medial or lateral relative to the desired optimal entry point results in variable calyx length and angle. This can interfere with proper entry and can result in excessive torque in the substance during rigid nephroscopy procedures in the renal pelvis system. The literature does provide guidance when determining the site of skin puncture. To avoid injury to the colon, the puncture should be medial to the posterior axillary line, but not too medial, as it can pass through the paravertebral muscles, resulting in increased postoperative pain and possibly directly over the renal pelvis without crossing the renal parenchyma. Punctures too close to the ribs may injure the intercostal nerves and blood vessels and should be avoided. For the inferior pole approach, skin puncture should be 1 cm below the tip of 12 and 1 cm medial to the rib. We have described the technique of determining the site of a skin puncture, which combines the advantages of bull's eye and triangulation techniques, hence the term hybrid technique. When arm C is at 0°, the skin site corresponding to the target calyces is marked as spot A. Then rotate the arm C 30° toward the surgeon. The dots on the skin that correspond to the target calyces and form a bull'seye with a needle are marked as spot B. In the bull's-eye technique, we perform the puncture at point B. However, in the triangulation technique, the puncture is aligned with the infundibulum along the axis of the stone. If we take the target calyces as the center of the sphere, then we have an imaginary circle on the skin where point A is the center of the circle. The distance from point A to point B is the radius of the circle. The radius remains the same regardless of the direction measured from the center of the circle. Therefore, when we take a line along the stone axis, we intend to make a puncture in it - the site of the skin puncture is marked with this principle. This means marking the B1 point on the skin such that the distance from A to B1 is equal to the distance between A to B, i.e., the radius of the circle centered on the target calyce. This is how we determine the site of skin puncture in the triangulation technique [(Figures 7 and 8).
Figure 7: Hybrid technology. The C spot is the calyces to be punctured. Point A corresponds to point C where the arm C is 0°. Point B corresponds to point C, and Carm is rotated 30° towards the surgeon. A needle fixed at point A or point B is seen as a bull's-eye effect on a Carm monitor. Measure the distance between points A and B.
Figure 8: Hybrid technology. The "A" is the point on the skin that corresponds to the target calyces, and the C arm is 0 degrees, the center of an imaginary circle. The distance from "A" to "B1" is equal to the distance from "A" to "B", i.e. the radius of the circle.
Once the puncture site has been identified, the next critical step is to enter the center of the posterior calyces with a needle at the appropriate angle. This step of hitting the calyx at depth typically requires manipulation of the C-arm in different directions, towards the surgeon (in the bullseye technique) or in the tilted head-tail direction (for the triangulation technique), and requires an understanding of the three-dimensional anatomy on a two-dimensional fluoroscopy monitor. This step requires maintaining the needle in one plane while adjusting it in the other, and it is not surprising that multiple attempts are required and perspective is overused in this step, especially for beginners. Maintaining needle orientation in one plane while making adjustments in the other plane is essential for proper puncture. It is also the steepest aspect of the learning curve for urologists trained in percutaneous nephrolithotomy. We describe our technique to determine the angle and depth of puncture in fluoroscopically guided prone percutaneous renal access using simple mathematical principles. We have used it in > 150 lower, middle, and upper pole punctures with a first-attempt success rate of > 95% and no pleural, visceral, or hemorrhagic complications. This has recently been accepted for publication. In the bull's-eye technique, the angle at which the needle is treated as a point is the angle at which the puncture is punctured. Our hybrid technology takes advantage of this principle. The needle is located at point B, the arm C is rotated 30° toward the surgeon, and the needle forms a bull's-eye; Use a protractor to measure the angle of the needle to the skin surface (Figure 9). It is important to note that the protractor is parallel to the operating table. Use the principles of spheres and circles as described earlier; If we hit the calyx using the triangulation technique from point B1, the puncture angle may be the same due to the uneven contours of the body surface, there may be a 1-2 degree variation. The third component of the hybrid technique is to determine the puncture depth. What we have so far is an imaginary triangle (Figure 9) that we know: (1) one side - the distance between points A and B marked on the skin; (2) an angle – i.e., 90°, 0° for the C arm; (3) Another angle – measured at point B with a protractor.
Figure 9: Hybrid technology. Use a protractor to measure the angle formed by the needle to the surface of the skin.
have this information; By using the Universal Triangle Solver application, we can determine the depth. In this application, if we put two angles and one edge together, then according to the sinusoidal theorem, it calculates the other two sides and angles. For example, if the distance AB is 4 cm, the protractor calculates an angle of 65°, while the other angle is always 90° – via the universal triangle solver – the depth will be 9.5 cm. The same principle can be applied to triangulation techniques. Arm C adjusted to 0°. The puncture line is aligned with the infundibulum from point A. Point B1 is marked on this line. Triangulation techniques can be used to enter from point B1 (Figure 8). The puncture angle was determined by the protractor earlier using the bull's-eye principle. The puncture depth is the same as previously calculated. Since the angle of entry is known and the depth is precalculated, the needle advances only in the 0° position of the C-arm (without placing it in an inclined position) and is punctured. In the technique we described, we assume that the target calyceum is the center of the sphere. If we have to hit the center of the sphere from the surface, then the distance from any point on the surface to the center is the same. So, once we have marked point B on the surface of the skin using the bull'seye technique, then mark point B1 for the skin entrance using the triangulation technique; Then the distance from C to B or from C to B1 will be the same, i.e., the radius of the sphere. Also, the angle of entry from B or from B1 to point C is almost the same, with only a small difference, since the contours of the body are not completely flat. However, this minimal difference does not pose any significant obstacle to achieving access through the described technique, as the angle of the puncture and the trajectory of the needle will not change much. We see this in our research. The difference between the calculated depth and the actual depth is 0-3 mm. In addition, because the angle of entry is known, fluoroscopy screening time and time required to achieve puncture are reduced because multiple movements of the C-arm are not required. The techniques we describe are suitable for both bull's eye and trigonometry. It describes the three most important things needed to achieve a successful percutaneous renal puncture: the skin entry site, the angle of entry, and the puncture depth. It relies on simple tools. Some mistakes may occur, especially if the protractor is not parallel to the operating table, but this can be easily overcome with minimal experience (the assistant tells the protractor whether it is parallel to the operating table). But so far, this technique has not been compared with others. The applicability and effectiveness of this technique in the hands of others has yet to be determined. This will require a controlled prospective study involving many surgeons with the same experience and comparing it with conventional techniques. It will then determine if the technology correlates with the shorter pivot time, higher accuracy, and smaller learning curve we are proposing. The grade of hydronephrosis affects the puncture, which is relatively easy for higher grades of hydronephrosis. However, if the angle, i.e., the trajectory of the puncture is correct, as described by the technique, the puncture will be easier and more accurate even in the case of a low degree of hydronephrosis.
Posterior calyceal puncture confirmation
If air is injected during opacity of the pelvic calyceal system, air will be inhaled, followed by free-flowing saline, especially when injected through a ureteral catheter. Thereafter, as the slip is passed, it is easy to enter the pelvis while maintaining the angle of the needle. No action is required. Conversely, if the anterior calyces are punctured, the sliding line will coil in the calyces and will not easily enter the renal pelvis or will take multiple manipulations to enter the renal pelvis (Fig. 10).
Figure 10: Calyceal puncture. A: If the posterior calyces are punctured, the slip line can easily pass through the renal pelvis; B: If the anterior calyces are punctured, the glide line will coil in the calyces before reaching the renal pelvis.
Gliding/passage of guidewires
If a 21G needle is used for puncture, the guidewire that initially passes through is 0.018 inches, which must later be replaced with a 0.035 inch guidewire. If an 18 G needle is used, a 0.035-inch slip wire can be passed. J-tip Teflon coated guidewires were initially used. Nowadays, the use of sloping tip hydrophilic slip lines is increasing. Maneuverability, kink resistance, and ease of passing through the affected stone in the ureter or coiled in a distant calyx are the long-range advantages of this line. But the slippery nature of the hydrophilic line makes it susceptible to displacement. Therefore, it should be replaced with a stiffer wire, such as a 0.035-inch Zebra or Amplatz super-hard guidewire. Another note to be aware of when passing through a hydrophilic slipline is to keep it moist. Dry tips can be hard and cause inadvertent perforation of the collection system.
Incision of the skin and fascia
The skin should be cut sufficiently so that the dilator and Amplatz sheath of the desired size can be easily introduced. The correct way to cut the fascia is to use a knife as a waist knife along the needle under fluoroscopic guidance. The fascia should be cut in two planes at right angles to each other. This is especially important for patients who have had scarring due to previous surgery. An 18 G coaxial fasciotomy needle (Cook) can be used, taking care to avoid tearing the subcostal or intercostal neurovascular bundle near the inferior border of the cost.
guidewires and safety wires
Traditional teaching places a lot of emphasis on placing a safety guidewire to access the tubing in the event that the working guidewire accidentally slips out. Nowadays, many surgeons find it unnecessary to place a second safety wire, especially when the guidewire passes all the way through the bladder, and even more so when it is an ultra-rigid guidewire . However, during the learning curve, it is prudent to use a safety line. This can be introduced with an 8/10Fr coaxial dilator (Karl Storz) with a double-lumen catheter or dilator cannula along with the initial lead. Expansion should be performed on a hard wire, not on a smooth hydrophilic wire.
dilate
Dilation of the canal to establish nephrostomy access is an integral step in PCNL. Ureteral dilation is performed to increase the size of the percutaneous guidewire access so that work instruments can be inserted into the pelvic system (PCS). In most cases, a dedicated dilator should be used to increase the size of the pipe to 24 or 30 Fr size. The function of the dilator is to enlarge the duct in a non-invasive way and make kidney access easier. The dilated duct is then maintained by placing an Amplatz sheath. Fasciculations can be acute or chronic [58]. Chronic dilation is accomplished by placing a percutaneous nephrostomy tube that is gradually dilated over several days by sequentially replacing a larger tube. Acute dilation is performed just before the treatment procedure. Dilation of the tract by sequential (Amplatz dilator) or telescopic coaxial dilator (Alken dilator). These are rigid dilators. Balloon dilators are also popular, with similar results to rigid dilators. The chronic dilation method used to be the usual method for performing renal access surgeries such as PCNL. However, in recent years, the primary acute dilation approach has become preferred due to its low patient morbidity, short duration, and less room for complications.
Alkens dilators
These are rigid metal spreaders introduced through a central guide rod. The progressively enlarged coaxial stainless steel dilator helps to expand the pipe from 8 Fr guide rod to 30 Fr. The guide rod has a rounded bulbous end to prevent continuous dilator overshoot. The advantage of the Alkens dilator system is that it is reusable, so it is inexpensive, and importantly, it is able to dilate even when perirenal scarring is dense. The downside is that the same characteristics that make the Alkens dilator so effective are also the reason why rigid metal dilators can cause considerable damage.
Amplatz expander
These are semi-rigid plastic dilators that guide the catheter through an 8-Fr PTFE catheter that fits into a 0.035-inch guidewire. They can also pass through guide rods. The dilators pass one after the other, not coaxial like rigid metal dilators, but by advancing one dilator, removing it, advancing the next larger dilator, and so on, until the final pipe diameter is reached. Finally, the working sheath is passed through the final dilator, and then the dilator and 8-FR catheter are removed, leaving the working line and sheath in place. The dilators are available in increments of 2 Fr, but if the expanded tissue is softer, it is not necessary to use each dilator. The advantage of the Amplatz dilator is that the collection system is theoretically less traumatic than the one that uses a rigid metal dilator, but the disadvantage is that bleeding occurs every time the dilator is withdrawn. Since these are disposable dilators, they are more expensive than Alkens dilators. Many comparative studies have been conducted between these two dilator systems, but experienced urologists have found no difference between the two systems in terms of safety. The Alkens dilator may be more suitable for patients with tight staghorn stones, as the Amplatz dilator requires some space in the calyx for dilation. In calyxes where there is no space, the expansion may remain shorter due to the tapered end of the dilator.
Balloon dilators
Here, a pressure balloon is used for fast track making. The Amplatz sheath is reloaded onto the balloon and placed once the balloon has been sufficiently expanded. Balloon dilators are expensive and can be difficult to use in patients with dense scar tissue. When surgery is performed on a hyperactive kidney, dilators may have an advantage. As it is a single-step dilation that results in tamponade, less bleeding is expected, but not all studies have recorded less bleeding and transfusion compared to the Alkens and Amplatz dilators. To make tubing fast, simple, and reduce blood, a variety of single-step techniques have been described. The easiest way to do this is to use the largest Amplatz dilator instead of the initial smaller dilator. In difficult cases where scar tissue is present around the kidneys, Corinthian knives or plasma vaporization have been used in pipe making]. The two new dilation systems described are the radial dilator system and the 5pang system. The advantage of both systems is that the needle is not removed, so the expansion exceeds the rigid system, reducing the chance of kinking the guidewire. Expansion will also be faster. However, to date, there has been no description of the single-center and multi-center experiences of these two systems. The important principles of expansion are: (1) Proper planning of procedures and proper selection of incoming calyxes are critical to the success of PCNL. This requires the study of radiological images prior to surgery; (2) The Tao should be extended only to small lamps. If overdilation occurs, it can damage the infundibulum region, renal pelvis, or uretero-pelvic junction. Trauma to the anterior wall of PCS can cause heavy bleeding that can be difficult to control. Under-expansion is always better than over-expansion and trauma-inflicting; (3) the success of tube building depends on maintaining the angle, depth and direction of expansion; (4) each step of expansion should be monitored under fluoroscopy; (5) The collecting system should be maintained by injecting contrast or saline into the system during dilation. This is instilled through a ureteral catheter by an operating room assistant; (6) Adequate luminotomy is important for safe dilation.
AMPLATZ 外鞘
The use of Amplatz sheaths in percutaneous kidney surgery has become standard. Regardless of the type of dilator used (rigid or balloon), or orbital dilation technique (one-step or multi-stage), always use the Amplatz sheath. The Amplatz sheath serves a variety of purposes: (1) the Amplatz sheath maintains the tubing during surgery; (2) Cause gastrointestinal tamponade and reduce bleeding. The beveled end of the Amplatz sheath can be used to tamponade a portion of the renal parenchyma that is actively bleeding; (3) Protect the renal parenchyma from damage by renal surgical instruments; (4) The use of Amplatz sheath maintains a low-pressure system and reduces fluid inosmosis. For patients infected with stones, it is important to maintain a low-pressure system because the risk of sepsis is reduced; (5) The Amplatz sheath helps remove stones and prevents parenchymal damage caused by broken jagged stone edges.
When are multiple punctures performed?
The amount of bleeding, parenchymal injury, morbidity, and risk to the patient increase with the number of punctures. It is important to plan the first puncture in such a way as to avoid multiple punctures. The use of flexible nephroscopes and flexible ureteroscopes can also reduce the need for multiple punctures. Multiple passages may be required to treat large, complex and antler-shaped stones. In this case, the first pass is made in such a way that most of the stones can be removed through it. The adnexal bundle can be a mini-PCNL bundle for peripheral stones. In this case, the upper calypium has an advantage because it has direct access to all the components of the upper calyx, renal pelvis, inferior calycea and upper ureter. In specific cases where the stones are smaller than the neck of the calyce, percutaneous calyceal lavage may be performed to flush the stones from the renal pelvis so that they can be picked up through the primary path. If necessary, multiple tablets can be made safely in experienced hands to completely remove stones. In the case of a complex, the management plan is as follows: make the main area in such a way as to clear the largest stones. If a holmium laser can be used for flexible nephroscopy, use it to prevent additional urethra. If these facilities are not available, percutaneous calyceal lavage, trails, or accessory tracts may be performed.
How do I make a secure second transaction?
The second or multiple transfusions tend to bleed more than the original one because it is impossible to make the system opaque when the second one is formed. The puncture is more often directed at the stone than at the pot. Anatomical structures can also be altered by bleeding and extravasation of the first line. To prevent this, if a second bundle is anticipated, it is best to place the guidewire in the calyx where the second bundle is expected before the first bundle expands. The advantage of pre-placement of a guidewire is that the catheter can be placed correctly, but the disadvantage is that dilation of the guidewire may not be necessary in some patients. The advantages of a properly placed piece far outweigh the risks of aiming at a small piece of stone.
How can I reduce radiation?
The risk of radiation in patients with stone disease during evaluation and treatment is quite high. Recently, two centers studied the radiation dose of a patient with a primary acute stone event over a 1-year period. They found that the average amount of radiation received in these patients was 29.7 mSv, and 20% of patients were exposed to > 50 mSv. This dose exceeds the International Commission on Radiological Protection recommendation for occupational radiation exposure limits, which are an average of 20 mSv over a 5-year period and no more than 50 mSv in any given year. In contrast, typical CT of the abdomen and renal pelvis did not contrast the patient's exposure to a median of 15 mSv[77]. Fluoroscopy during percutaneous nephrolithotomy is associated not only with the patient's radiation exposure, but also with the surgeon and operating room staff. High body mass index, high stone load, and increasing number of pathways are associated with increased radiation exposure. The presence of branching stones and hydronephrosis is associated with reduced radiation exposure. Proper planning of surgery by an experienced surgeon is important to reduce radiation exposure. It is the surgeon's duty to reduce this health hazard for all involved. During the PNL, the following steps can be taken to minimize radiation: (1) surgeons and staff must wear radiation protective clothing, thyroid shields, and radiation protective gloves at all times; (2) It is important to limit exposure to the minimum necessary. Radiation exposure is reduced using short-pulse fluoroscopy and the "Last Image Hold" feature using fluoroscopy devices; (3) The image intensifier should be placed as close to the patient as possible, the fluoroscopic beam should come from under the table, focus on the area of interest and should use pulsed fluoroscopy mode [25]. The use of air instead of iodinated contrast agents can further reduce radiation exposure; (4) Keeping fluoroscopy device footrests with the surgeon and thinking about other small precautions during and after screening that can reduce radiation; (5) For lower pole puncture using triangulation technique, tilt the C arm cephalad or vice versa for upper pole puncture; (6) Hold the needle so that the radiation exposure of the hand is minimized. Using instrumentation to achieve this will reduce radiation exposure. Needles and dilators marked with distance help reduce radiation because fluoroscopy can be used once the tip of the needle is close to the kidney.
Prevent visceral injury during PCNL
Any abdominal organ close to the kidneys can be injured in percutaneous kidney surgery, including the colon, duodenum, jejunum, spleen, liver, and biliary system. This kind of injury is always an accident and needs to be prevented by an effort. If this happens, early recognition and treatment are very important.
Colon injury
Colon injury occurs in about 1% of prone percutaneous kidney surgeries. This is thought to be due to the postrenal location of the colon. The left side is more common when lower calyx entry is attempted [86]. Emaciated patients, older age groups, colonic distension, previous colon surgery or disease, and the presence of horseshoe kidneys are additional risk factors [40, 87]. It can also occur in bariatric surgery, ileal disease, and patients who have significant weight loss in a short period of time after resection. A recent hypothesis has proposed that the retrorenal colon is an acquired abnormality [88]. On the 2nd, 5 patients developed the PCNL stage of colonic injury. All of these patients had long-standing large hydronephrosis that was initially drained by nephrostomy or DJ stent. They proposed that the mesocolon lengthens on the progressively dilated obstructed kidney. Once the kidneys are unblocked, the kidneys shrink, but the long mesocolon remains. The colon with a long mesocolon descends to the back of the kidneys, forming the postrenal colon. Preventing colon damage is very difficult. In patients susceptible to colon injury, a preoperative prone CT scan can help determine the position of the colon relative to the intended bowel. Checking the awareness of the colonic bubbles through fluoroscopy may help prevent this injury when conducting visits and monitoring for any changes in the bubbles. If ultrasound-guided puncture is attempted, the covered colon can be identified.
Liver and spleen injury
Normal-sized liver and spleen injuries are very rare during PCNL and are likely to occur if puncture is above the 10th rib. In patients with splenomegaly and hepatomegaly, a preoperative CT scan can be used to identify safe pathways. In rare cases, CT-guided visits may be available. Preoperative awareness and planning are the only ways to prevent these injuries.
Pleural injury
Pleural injury is a definite risk associated with supracostal access. All supracostal tracts pass through the diaphragm and therefore carry a risk of damage to the pleura and lungs. The surgeon should be aware of this risk when performing a supracostal puncture. As the fiber bundles move higher over the intercostal space, the risk increases. The risk of entering the 12th rib is about 4%, while the risk of entering the 11th rib increases to almost 20%. To understand pleural injury during PCNL, it is important to understand pleural anatomy. The parietal pleura passes through the 12th rib and the medial half is covered by the pleura, while the lateral half of the rib is not covered by the pleura. In the midline of the scapula, while the parietal pleura is at the level of the 12th rib and the visceral pleura is at the level of the 10th rib. The parietal and visceral pleura rises cranial and lateral on the ribs and rises further on deep exhalation. To prevent pleural invasion: (1) place the fascicle lateral to the midline of the scapula; (2) Keep below the 10th rib as much as possible; (3) Album should be made during a deep exhalation; (4) The site shall be kept to the minimum size necessary. Based on the above anatomical considerations, it is suggested that a bundle below the 11th rib lateral to the midline of the scapula will miss not only the visceral pleura, but also the parietal pleura. Fascicles formed through the parietal pleura may not be clinically significant. The use of the Amplatz sheath prevents leakage of irrigation fluid in the pleural space, further alleviating major complications. An anesthesiologist who understands the surgery and is involved during the procedure is important because he will keep the patient on a deep exhalation while making the tubing. If individual cases require a higher length, it doesn't hurt to make it. Using thoracoscopic control will make this safer. If a pleural effusion occurs, it can be easily managed by placing a chest drain at the end of the procedure. It is important to check the costo-diaphragmatic angle at the end of the supracostal pathway. A clear costo-diaphragmatic angle under fluoroscopy at the end of surgery is evidence that the pleura is not violated.
Problems in the channel establishment process
Failure to make the system opaque
Causes: This uncommon condition may be due to a ureteral catheter slipping out or a tightly impinged stone preventing the passage of contrast medium. Prevention: The ureteral catheter needs to be secured to each urethral catheter that was initially inserted so that the patient does not slip out when the patient is prone to do so. The use of hydrophilic slip wires can also help to pass through the stone through the guidewire and ureteral catheter. Remedy: For a stone with a tight impact, the contrast medium does not pass through it. Holding the patient in a "down" position or decreasing the concentration of the contrast medium (increasing the dilution) may help some of the contrast agents to overtake obstructive stones. If that doesn't work, ultrasound-guided puncture can be tried, or a Chiba needle can be used to make the system opaque. The Chiba needle is a thinner needle than the original needle, so it may be less invasive [96]. The needle is introduced approximately 2 cm lateral to the transverse process of the L1-2 horizontal vertebral body. At this site, it is likely to hit the renal pelvis. CT scan images can help determine the exact location of the renal pelvis. Once the Chiba needle is entered into the PCS (confirmed by aspiration of urine from the PCS), the system is made opaque and a standard tubing is formed through the selected calyx.
Extravasation of contrast agent
Cause: Contrast extravasation is an unfortunate problem. It is important to avoid this because extravasation occurs before the main procedure begins and can complicate further visits. Extravasation of the contrast agent can make access difficult and can also prevent radiographic confirmation of stone removal after surgery. The most common reason is that enthusiastic assistants inject a lot of contrast under high pressure. Rarely, the dye may leak out of an improperly placed ureteral catheter. This is more common in patients with large ureteral stones and infection. It can also occur intraoperatively when the first attempt to insert the needle is unsatisfactory and the contrast leaks from the needle puncture site in the collection system. Prevention: To prevent extravasation of contrast medium, the diluted contrast agent is injected slowly while the ureteral catheter is kept in the pelvis to avoid sudden expansion of the system that can cause extravasation. It is important to instruct the assistant to gradually inject a small amount of contrast medium at very low pressure. The volume of the normal collection system is 5-8 mL; Therefore, it is crucial to instill small amounts gradually. Remediation: This can be addressed in a number of ways: (1) Give a diuretic and wait for the contrast medium to be absorbed. If you wait for about 15 minutes after furosemide injection, the exuded contrast concentration will decrease significantly; (2) The use of a concentrated contrast agent, by dilution of the extravasation contrast agent, helps to identify PCS. Before the concentrated contrast agent can exudate and aggravate the problem, a rapid treatment is required; (3) Use air pyelogram to identify PCS. Similar problems with air extravasation can occur through pinholes in the cortex; (4) Ultrasound-guided percutaneous access is a good choice. However, even this technique is difficult after extravasation of contrast medium. If you want to have an ultrasound, don't try an air pyelogram; (5) rarely, it may be necessary to phase the procedure and retry access after 48 hours; (6) Grasso et al. initially described ureteroscopy-assisted percutaneous renal access as a rescue procedure in difficult cases. This can be used in cases where significant extravasation occurs. The main obstacle is the provision of a flexible scope, which is not present in many developing countries; (7) Giannakopoulos et al have described the use of an angiographic catheter to salvage the condition. A 0.038-inch guidewire is threaded through the ureteral catheter with an end opening, then removed, and passed through an angled, tipped angiography catheter. Despite the apparent extravasation of the contrast medium, the radiopaque tip of the angiography catheter is easily visible under fluoroscopy. The guidewire is then threaded through the angiography catheter. It is manipulated and brought into a calyx to be punctured. The angiographic catheter is then moved to the calyx and punctured against the catheter tip. The initial normal fluoroscopy images captured on the second monitor of the fluoroscopy unit on intravenous urography film or before extravasation are very helpful for manipulating the guidewire and catheter in the appropriate calyx.
The puncture was unsuccessful
Cause: Unsuccessful puncture is usually a technical problem. This may be due to the operator's inexperience, or it may be due to the technical difficulties that often arise when attempting to puncture an undilated system. This may be related to incorrect selection of puncture calyxes. Prevention: Having more experienced colleagues present during the initial learning phase helps minimize the learning curve and overcome difficulties in the process. It is important to keep the PCS adequately filled to facilitate puncture. The assistant is asked to constantly flush the fluid in the ureteral catheter to keep the system inflated. If it is still difficult despite multiple attempts, re-evaluate the preoperative radiology and re-plan the puncture. Add a drop of methylene blue or betadine solution for comparison; Aspiration of colored fluid (blue or brown) from the kidneys will give confidence in proper puncture. Remedy: In non-dilated systems, fluoroscopy-guided puncture is often feasible using the techniques described above. If the surgeon is concerned about trauma to the kidneys, then it is prudent to use a 21 G needle for the initial puncture and pass through a 0.018-inch guidewire, which can be replaced with a 0.035-inch stiffer guidewire. If these attempts fail, seek help from a senior colleague in the department. An interventional radiologist may help with a difficult puncture. Rarely, it is necessary to reschedule surgery under CT scan guidance or ultrasound guidance and puncture is also difficult in patients with very thin renal cortex. The renal cortex tends to move away from the needle or be held up by the needle rather than punctured. Once close to the cortex, pushing the needle firmly in can help the needle enter the PCS. Forced insertion is safe because the PCS may dilate greatly in this patient with a thin renal cortex. In these patients, it is very important to care for the leads correctly once inserted. It's also important to keep a safety line if possible. If a urethral defect is present, it is difficult to access these deflated hydronephrosis sacs. For very thin patients, the puncture can also be awkward. Since there is no perirenal fat pad, the kidneys tend to be pushed by needles.
There is blood at the tip of the needle instead of urine
Causes: It is not uncommon to have blood instead of urine after the puncture is performed and the trocar and aspirate are removed. This can happen if the needle is in a blood vessel or if the needle is in the renal parenchyma rather than in the pelvic system. This can also happen if there are multiple attempts to achieve access. Prevention: Avoid trauma by using multiple puncture attempts with an 18 G needle instead of using a 21 G needle. Follow the proper puncture technique so that we can aim the cauldrium through the vault. Exclusion method: If the effluent is cleared after injection of normal saline through the ureter, it indicates that the needle tip is in the collecting system and the slip can pass through the collection system. If the fluid flowing out or aspirated is pure blood, the needle should be repositioned. This requires pulling the needle and adjusting the middle and front positions. What usually needs to be adjusted is the depth of the needle. The needle is on the surface or deep of the desired calyx. This adjustment is best done after the needle has been removed from the parenchyma. Intraparenchymal manipulation is traumatic and should be avoided. The 3-finger technique described by Shergill et al. is an attempt to help beginners overcome this difficulty. The needle tip should be toward the desired calyce, with arm C in the anteroposterior position, or tilted toward or away from the surgeon, or tilted in the ceptocaudal direction. The surgeon should keep in mind that medial adjustment should be made when the C-arm is at 0 0, and the depth adjustment should be made after the C-arm is tilted towards or away from the surgeon, as in the bullsle-eye technique, or in the head-tail direction, such as the triangulation technique. An easy way to determine depth is to place another needle on the surface of the skin above the target calyx. If the calyces are between the two needles, the needle is deep and surface adjustment should be made. If the target calyces are below the two needles, the needle is superficial and should be adjusted in the direction of depth. These problems are minimized by the use of the hybrid techniques described above.
It is not possible to park the guidewire
Causes: This can happen if the slipline is outside the collecting system, or if the calyces are completely occupied by stones. In rare cases, accidental puncture of a kidney cyst and aspiration of clear fluid can lead to an erroneous belief that the puncture is good. But in this case, the slipline does not enter the collection system. If the anterior calyceum is punctured, the slip line will not easily enter the renal pelvis (Figure 10B). Prophylaxis: free flow of urine from the needle is usually a sure sign of proper puncture. Hydrophilic slipwires usually easily pass through the pelvis and even through the affected tartar. For inadvertent puncture cysts, ultrasonography findings and intravenous urography or CT scan images should alert the surgeon to this possibility. Remedy: If you suspect that the slip line is outside the system, re-puncture or reinsert the slip line. Injection of diluted contrast medium or diluted methylene blue can also confirm that the needle is correctly positioned in the desired calyx. There may be a stone blocking the passage of the subureteral ureter, in which case the second best place to place the guidewire is the distal calyce. If the wire is not coiled in the distant calyces, keep the wire as long as possible in the punctured calyces [99].
The guidewire is kinked
Cause: This is usually due to strong expansion in the wrong direction and/or resistance from the initial dilator. Once the guide rod is in place, this problem does not occur. Prevention: Wires are usually kinked at the level of the thoracolumbar fascia. Therefore, the fascia needs to be cut before the expansion begins. The use of super-rigid wire is recommended because it is more resistant to kinks than PTFE guidewires [101]. Expansion should be in the right direction and with sufficient strength. A simple rule is to achieve 2/3 of the dilator and 1/3 of the force by rotating the tightening motion. If there is doubt about the correct direction, then moving the slipline will give a good indication. If the traverse moves freely, it indicates that the direction and trajectory are correct. And vice versa, if the slipline can't move freely, you need to adjust the direction and trajectory. This simple friction test is of great help in getting an initial understanding of the percutaneous renal pathway. The use of a 5-part PANG needle system largely avoids this problem. Remedy: If a kink occurs, the initial dilator should be advanced closer to the kink and pulled inside the dilator. The right direction should then be determined and further expansion should be made. Sometimes repuncture is needed. If you have inserted a security cord, you can use it for expansion. Recently, Lezrek et al described the use of double pronged forceps to overcome renal mobility and prevent guidewire kinks during catheter dilation.
Insufficient expansion
Cause: Inadequate dilation is that the guide line is initially well placed, but during dilation, the dilator and Amplatz sheath remain shorter than the PCS. This usually happens early in the learning curve. The use of the Amplatz dilator is also relevant to this, as the distal tapered end of the dilator enters the calyx, but the amplatz sheath introduced on it does not enter the calyx and remains outside the collection system. This may cause rapid bleeding because a portion of the parenchyma has been partially dilated without the packing effect of the Amplatz sheath. This situation needs to be managed quickly. Prevention: Flushing saline from the ureteral catheter during dilation can help confirm if the dilator/dilator is within the collection system by observing the flow of saline out of the dilator. A small number of frequent screenings on the C-arm confirm the correct position of the dilator. Remediation: Treatment will depend on the position of the guidewire. If the wire is still inside the PCS, thread the guide rod through the wire so that the bulbous end of the rod is positioned in the PCS under perspective. In this case, it may be easy to use a flexible guide rod. Once the guide rod is placed, use the Amplatz dilator to expand the remaining undilated tubing and reposition the Amplatz sheath in the collection system. If the lead also slides out and the nephroscope is outside the parenchyma of perirenal fat, it is important to find the hole in the renal capsule, through which partial dilatation is made. This can be identified as a parenchymal bleeding site. To identify this site, it may be necessary to reduce the flushing pressure of the nephroscope so that venous bleeding is visible. Once determined, the guide rod is passed through the capsular foramen and its position is confirmed under fluoroscopy. A guidewire can be placed through the rod to ensure secure access. Once this is done, the remaining expansions can continue with the Amplatz dilator. If no bleeding site is found, some colored fluid is needed to identify the cyst foramen. Methylene blue or betadine solutions can be used. Methylene blue solution should be very thin. Add 1-2 drops of methylene blue to 10 ml of normal saline. For betadine solutions, undiluted or one-in-one diluted betadine can be used. Either solution is flushed through the ureteral catheter. Note the outflow of the colored solution. Once identified, a guide rod is passed through the site and the remaining dilation is continued. If the puncture site cannot be identified despite the colored solution, try re-piercing and repeating. This can be difficult because the contrast agent may overflow, or the calyx may not be able to fill due to a leak of the contrast medium. It may be helpful to choose access through another calypium or ultrasound-guided puncture. In rare cases, the procedure may be required. The puncture site is sealed within 48-72 hours, after which the procedure can be repeated.
Overextended
Cause: Overexpansion is a state in which the dilator passes through the opposite wall of the PCS and the Amplatz sheath is now placed in front of the kidney. Forced expansion is a common cause of this problem. Prevention: Hold the guide rod tightly, rotate and expand 2/3, and force 1/3. Dilation to the calypium should be attempted rather than calculus. It's always better to underexpand than to overexpand. Remediation: The problem with this complication is that when the Amplatz sheath is retracted to allow it to enter the PCS, the dilated anterior wall does not produce any packing and may bleed rapidly. In addition, the flushing fluid can leak through the holes in the front wall. Further nephroscopy will become difficult as the PCS may collapse due to fluid leakage. Oozing fluid can cause severe fluid overload. Even stone or stone fragments can migrate outside of the PCS through holes in the anterior wall. The Amplatz sheath needs to be gradually withdrawn until the sheath is back into the PCS. Further planning after that will depend on the size of the piercing and the amount of bleeding. If the overdistension results in a small perforation of the renal pelvis, then a person can properly return to the system and complete the procedure quickly without causing excessive extravasation. However, in the event of a large perforation or massive bleeding, it is prudent to insert a nephrostomy tube, abandon the surgery and live to another day. In this case, a large-bore nephrostomy tube is always retained. The second surgery can be done after 3-4 days as the piercing usually heals during this time.
Channels are missing
Cause: During nephroscopy or lithotripsy, the Amplatz sheath has slipped out of the PCS. This happens when the slipline slides out before the expansion is complete. Sometimes during stone fragmentation, the guidewire will come out, and if the amplatz is not properly secured, it will also come out of the collection system. Prevention: To prevent channel loss, the guidewire should be adequately parked in the collection system or through the bladder. The use of safety threads is another way to prevent complete loss of the ureter. Super-rigid guidewires are also used instead of smooth, hydrophilic slipwires to prevent a complete loss of traction. Remediation: Treatment depends on the location of the guidewire. If the guidewire or safety wire is well placed, the guidewire can be followed endoscopically until the nephroscope is positioned in PCS; Once placed, the Amplatz sheath can be passed through the nephroscope. If there are no wires, the steps are the same as for underexpansion. Look for the site of bleeding or look for the outflow of colored fluid. An important problem with losing the urethra is that stones or fragments of stones may squeeze out and may be misplaced in the perirenal fat. These stones can be a source of ongoing infection. If possible, an attempt should be made to remove all stones. During endoscopic exploration of the perirenal space, the flushing pressure is reduced so that the patient does not fall into a state of fluid overload. If, despite concern, the prominent stone is misplaced in the perirenal fat, it is important to document the opaque shadows seen on postoperative imaging outside of PCS. They can cause concern for patients, so it is crucial to explain them appropriately.
conclusion
“Good results of surgery are results of good surgery”.。 This adage is best suited for the percutaneous renal pathway, as the correct pathway largely determines the success of PCNL. More innovation will emerge in the management of kidney stones, and technology will make percutaneous access easier in the future; However, adherence to an understanding of renal anatomy will remain the basis of percutaneous renal pathways.