Preoperative Planning and Preparation
Ureteropelvic junction (UPJ) obstruction can present symptomatically or as a serendipitous radiologic finding in a fetus/newborn or asymptomatic patient. Initial imaging, most commonly by sonogram or computed tomography (CT), reveals pelvicaliectasis of the affected renal unit(s), and the degree of cortical thinning may correlate with the chronicity of the obstruction. Functional assessment is necessary to determine the degree of obstruction of the dilated unit; diuretic nuclear renography is usually superior to contrasted imaging studies (intravenous pyelography, contrast CT, or MR urogram) because it provides quantitative measurements of differential renal function and drainage (T 1/2 ). Neonatal presentation after a prenatal diagnosis of hydronephrosis is common, but strict definition of UPJ obstruction in the asymptomatic infant remains elusive.
It is ideal to perform pyeloplasty without an indwelling ureteral stent or percutaneous nephrostomy in place. The former induces thickening of the ureteral and pelvic walls that complicates suturing; the latter can complicate mobilization of the kidney and lead to bacterial colonization/infection of the renal pelvis. Some surgeons prefer removal of an indwelling ureteral stent for some period of time before surgery, if the patient can tolerate it. Preoperative antibiotics are standard. Culture-directed antibiotics should be considered up to a week in advance if either type of tube is present.
Without contrasted imaging, the ureteral anatomy is not defined. For the vast majority of cases, additional imaging of the UPJ and ureter is not necessary if functional studies demonstrate obstruction. An antegrade contrast study is simple to obtain if a nephrostomy tube is present. If there is sufficient doubt or other unusual anatomic features (such as horseshoe kidney or renal malrotation), a retrograde pyelogram can be obtained under the same anesthetic as the pyeloplasty. A percutaneous antegrade nephrogram can also be performed on the operating room table before making an incision and has primarily been described with the dorsal lumbotomy approach (see below).
Patient Positioning and Surgical Incision
Successful open pyeloplasty can be achieved through a variety of approaches. The majority of urologists are most comfortable with the flank approach . Because access is needed only to the UPJ and not to the entire kidney and vessels, the incision can be lower than for nephrectomy. The simplest approach is an anterior incision extending anteriorly from the tip of the 12th rib. This incision allows the greatest flexibility for more complex cases, such as those with extremely large or malrotated renal pelves. Its extraperitoneal approach minimizes risk to the other viscera and speeds recovery. An anterior subcostal incision provides excellent visualization, but special care must be taken to keep the dissection extraperitoneal. Dorsal lumbotomy can reduce operative time and postoperative convalescence but is an approach less familiar to urologists. Because of its limited adaptability to complex anatomy, percutaneous pyelography after draping has been employed by some to confirm the anatomy before the lumbotomy incision. In cases of bilateral UPJ obstruction, either approach can be used on both sides in the same setting instead of a midline transperitoneal approach .
After anesthesia is established but before the patient is positioned, an indwelling urethral catheter should be placed to prevent bladder distention, which may impair ureteral emptying and lead to anastomotic leakage. It may also be helpful to confirm placement of an indwelling stent, if used. (see below).
A straight flank position is ideal for the 12th rib anterior incision. This is easily achieved in infants in a lateral decubitus position by placing a rolled towel or intravenous fluid bag under the contralateral waist on a flat table. The infant can be stabilized by strips of wide tape across the child at the shoulder and hip. Older children and adults are better positioned by placing the table in the flexed position with the kidney rest raised at the patient’s waist ( Fig. 15.1A ). If an anterior subcostal approach is desired, the patient can be rotated posteriorly in torque-flank position . The use of a beanbag to secure the patient can be beneficial in larger patients. Meticulous attention to positioning with an axillary roll below the down (contralateral) arm, padding under all extremities, and support of the up (ipsilateral) arm cannot be emphasized enough. The prone position is used for the dorsal lumbotomy approach; rolled towels or foam/gel rolls should be used to elevate chest and abdomen and allow the legs and arms to lie lower than the back. The arms are placed are placed above the head on pads. Be sure that ECG pads, electrocautery pads, and IV lines are not near the surgical field or under the patient to create pressure points.
The flank incision is made from the tip of 12th rib anteriorly to no further than the lateral edge of the rectus muscle. In infants and small children, 3–4 cm should suffice. The incision should follow the skin lines to minimize the scar. A combination of cautery and fiber separation can be used to dissect through the three muscle/fascial layers: external oblique, internal oblique, and the transversus abdominis. Care must be taken to identify the intercostal nerves that lie between the latter two layers and protect them with a vessel loop, if necessary. Once opened, the transversalis fascia should be dissected from the underlying Gerota fascia and peritoneum to prevent tearing when the self-retainer retractor is inserted. Also, small perforating vessels can be encountered that can lead to undesired bleeding. The dorsal lumbotomy incision has been traditionally described as a vertical incision lateral to the paraspinal muscles with the 12th rib and bony pelvis as the upper and lower limits. Alternatively, a horizontal incision midway between the two bony structures can be made parallel to the skin lines to minimize the scar, and then skin flaps must be raised superiorly and inferiorly to allow the lumbodorsal fascia to be opened vertically between the rib and pelvis.
Optimal magnification with loupes is preferred for precise dissection and closure to avoid postoperative leakage or anastomotic stricture.
Through the flank incision, Gerota fascia should be opened vertically as far posteriorly as possible to avoid inadvertently entering the peritoneum (see Fig. 15.1B ). The opening should be angled posteriorly while proceeding cranially because the peritoneum sweeps more posteriorly to include the liver (on the right) and spleen (on the left). The dorsal perinephric fat should be undisturbed, if possible, because this may be used later to cover the repair. Progress can be made posteriorly by rotating the kidney anteriorly with a sponge stick.
Once the renal hilum is seen, greater exposure can be gained by placing a vein or Gil-Vernet retractor at the junction of the renal parenchyma and hilum (see Fig. 15.1C ). Unlike a nephrectomy, there is no need to mobilize the entire kidney unless the UPJ obstruction is secondary to a long segment of narrowed ureter. The pelvis is then cleaned of fat to expose the UPJ. A retraction suture of 4-0 SAS in the pelvis is helpful in rotating and lifting the pelvis during dissection. With a hugely dilated pelvis, decompression of the pelvis with a 23- or 25-gauge butterfly needle may be required to gain exposure to the entire pelvis (see Fig. 15.1D ). In chronically obstructed systems, there is often a thick rind that must be dissected off the pelvis, often in layers. Bleeding from the investing fine vasculature can be controlled with a bipolar or low-current needle point cautery, using care not to injure the underlying pelvis.
The ureter is identified distal to the UPJ and cleaned of investing fat and fascia. A vessel loop will aid in mobilization of the ureter for several centimeters below the UPJ ( Fig. 15.2A ). Dissection should involve as short a length of the ureter as possible with preservation of the adventitial vessels to prevent devascularization that could result in postoperative stenosis. For secondary procedures, it may be easier to find normal ureter distally and then dissect proximally toward the scarred UPJ.
One must always be on the lookout for an aberrant lower pole vessel crossing the UPJ (see Fig. 15.2B ); palpation for pulsations can be helpful to confirm the presence of a crossing vessel. Crossing lower pole vessels are a more common cause of UPJ obstruction in older children, particularly in those presenting with intermittent renal colic versus isolated intrinsic narrowing of the UPJ more commonly found in infants.
Once the pelvis, UPJ, and upper ureter are free of surrounding fat and rind, the anatomy must be carefully analyzed to determine the optimal technique for repair. The variations in obstruction location include (1) at the UPJ with a high insertion on the pelvis, with or without intrinsic narrowing, (2) at the normally positioned UPJ due to intrinsic narrowing, (3) in the upper ureter due to stricture, valve, or polyp within the lumen, or (4) at the UPJ with extrinsic compression to a crossing vessel to the lower pole of the kidney. In the latter case, intrinsic narrowing within the lumen can coexist because of chronic irritation/compression. If there is doubt regarding the exact position of obstruction, the pelvis can be filled with saline through a butterfly needle to delineate the transition point where the dilation ends.
For a short stenotic segment, it is best to excise the narrowed and often dysplastic portion of ureter; therefore, a dismembered repair is ideal. The dismembered repair also allows for precise reduction in the size of the pelvis when indicated in widely dilated systems. Failure to adequately reduce the size of the pelvis in such cases can lead to postoperative obstruction due to kinking of the pelvis and repaired UPJ segment. The dismembered pyeloplasty is the most widely used repair because of its simplicity and efficacy, but it does have greater potential for postoperative obstruction because of scar contracture of the circular anastomosis.
Nondismembered repairs can be used for specific situations. The Foley Y-V plasty is used in high insertion UPJ obstruction to remodel the UPJ into a funnel shape at a most dependent position on the pelvis. Flap techniques, such as the Culp and Scardino repairs , may bridge the gap between the pelvis and healthy ureter in cases with long or more distal obstructions. The Davis intubated ureterostomy is reserved for the longest of obstructions.
Dismembered Pyeloplasty (Anderson-Hynes)
A stay suture of 4-0 SAS is placed in the anterior surface of healthy ureter below the obstruction parallel to its course. The ureter is then transected in a normal segment below the stenotic segment ( Fig. 15.3 ). If there is intrinsic narrowing of the ureter, no urine will drain from the pelvis at this point. In cases with a crossing vessel, the ureter is cut below the crossing vessel and pulled to the opposite side of it, and often little reduction in the size of the pelvis is needed. To ensure patency of the distal ureter, gently pass a tube down the ureter. Some feel that the tube should be passed into the bladder to ensure that there is no coexisting distal or ureterovesical junction (UVJ) obstruction, whereas others feel that such a concomitant lesion is exceeding rare and that tube passage could create edema at the UVJ that could impair necessary antegrade drainage. A 5F feeding tube works well in most cases, but a 3.5F umbilical vein catheter may be necessary for infants.