December 22, 2008 Leave a comment
For centuries, “cutting for stone” was synonymous with urology, and just over a decade ago it still made up at least one-fourth of the surgical activity in the field. The development of extracorporeal shockwave lithotripsy (SWL) and endoscopic stone surgery shattered this tradition, and the change becomes most obvious in the indications for ureterolithotomy. Once one of the most common procedures in urology, it all but vanished in the last years in spite of the fact that almost 50% of all patients with upper tract urolithiasis coming to treatment today have stones impacted in the ureter.8 Specifically, the development of ultrathin semirigid and flexible ureteroscopes with effective laser, electrohydraulic, or ballistic lithotripsy laparoscopic ureterolithotomy, and third-generation lithotriptors with ultrasonic and fluoroscopic stone localization and small focal zones, which can be pinpointed onto ureteric stones even in infants, have closed the last gaps in the spectrum of minimally invasive therapy of ureteric calculi.
With less invasive methods of stone removal, a sudden change of the position of the calculus can be met without major problems, even when noticed only during the intervention. In open stone surgery, this could result in a catastrophe, with failure to remove the stone and the need for further procedures. The time-honored rule of precise delineation of the size, number, and shape of all calculi and their topography within the collecting system before an incisional procedure remains as valid as ever.
In general, ureteric stones can be located precisely with a good intravenous pyelogram with appropriate oblique, delayed, and postvoiding films. To differentiate radiolucent stones from tumors, clots, or papillae, a nonenhanced abdominal computed tomography may be helpful, but significant stones may be missed with this technique, even when 5-mm cuts are obtained at the level of interest. Retrograde ureterography and, if needed, diagnostic ureteroscopy immediately before surgery will clarify the situation. Urinary infection should always be treated with appropriate antibiotics before surgery. With severe obstruction and any evidence of infection, it is prudent to first drain the kidney by percutaneous nephrostomy for about 48 hours until any pathogen is cultured and adequately treated.
A plain abdominal roentgenogram is always obtained immediately before surgery, before anesthesia is initiated. Even the largest calculus seemingly incapable of changing its position may do so, and this may necessitate a completely different surgical strategy.
INDICATIONS FOR SURGERY
In general, ureterolithotomy today becomes necessary only where ESWL or endoscopic techniques fail. Usually, these failures are concomitant with a complication of previous therapeutic interventions, in particular endoscopic manipulation. Urinary extravasation, an impacted ureteral basket, ureteral avulsion, and an obstructing stone are the typical scenarios. At the author’s institution, incisional surgery was required in only six of 3,123 patients subjected to a therapeutic intervention to remove ureteric stones in a 7-year period. Two patients had suffered ureteric avulsion, one patient had a basket trapped around a stone, in two patients stones could not be reached endoscopically, and one patient, pregnant in the fourth week of gestation, required rapid removal of a very large stone impacted in the lumbar ureter. Stones can of course also be trapped above congenital or acquired ureteric strictures. Where these require surgical correction, the stone is removed at the time of reconstructive surgery, but the underlying pathology dictates the surgical strategy and technique.
Alternatives to open ureterolithotomy are observation, which is indicated in small (<5 mm) stones with no signs of sepsis or extravasation, or one of many forms of minimally invasive surgeries including SWL, endoscopic extraction (via cystoscope, nephroscope, or ureteroscope), percutaneous stone surgery including laparoscopic removal, endoscopic destruction of the stone, or, in certain stones such as struvite or uric acid, chemolysis.
In the difficult situations in which ureterolithotomy is still indicated today, ample exposure is usually needed. Many of the minimally muscle-splitting incisions designed for specific stone situations in the past, such as the Foley incision through the lumbar triangle for high ureteral stones, the gridiron incision for midureteral stones, and the transvesical or transvaginal approach for intramural stones, have become obsolete. They provide only limited access to a small segment of the ureter and should be avoided in difficult situations, especially if the surgeon has limited experience with them.
The entire proximal half of the ureter is best approached by a modified 12th-rib supracostal incision, which is carried anterior to the tip of the rib (anterior supracostal incision). Large, firmly embedded stones in the area of the ureteropelvic junction can be removed with minimal morbidity through a posterior lumbotomy. The distal half of the ureter is best reached by a suprainguinal extraperitoneal access.
Anterior Supracostal Approach
The patient is placed in a lateral jackknife position. The skin incision runs parallel to the upper margin of the 12th rib and distally in the line of the rib. Its length depends on the precise nature of the procedure. For a standard ureterolithotomy in the lumbar ureter, an incision along the distal half of the rib extending 5 to 7 cm into the abdominal muscles suffices. It can be extended anteriorly as required to reach lower stones and posteriorly so that the entire kidney can be mobilized if necessary.
After the subcutaneous fat has been divided, the fibers of the abdominal musculature are incised with cutting diathermy immediately beyond the tip of the 12th rib . The transversus abdominis muscle blends here with the deep leaf of the thoracolumbar fascia and should be divided along the same line. The second and third fingers of each hand are now used to sweep the peritoneum off the underside of the abdominal wall muscles before the muscle incision is extended medially as required. The incision should be kept strictly in line with the extension of the 12th rib so as to keep well clear of subcostal vessels and nerves. Once it has been carried as far medially as needed, dissection can proceed in the opposite direction along the 12th rib. The latissimus dorsi and intercostal muscles are divided by diathermy moving backward along the upper margin of the rib. As the rib is progressively mobilized, the insertion of the diaphragm and the pleural reflection come into view. The subcostal nerve is carefully preserved as the diaphragm is divided flush with its insertion to the abdominal wall. The pleura is pushed away by blunt finger dissection. Depending on the degree of exposure needed, dissection of the 12th rib may proceed up to the vertebral column. After division of the costovertebral ligament, the 12th rib can be swung outward like a door. A rib retractor or modified Wickham ring retractor permits excellent exposure. The peritoneum is retracted medially, and the ureter is exposed in the retroperitoneal space below the lower pole of the kidney, where it already lies outside of Gerota’s fascia. If the stone lies higher, Gerota’s fascia is incised, and the ureter is followed upward to the stone, tilting the kidney anteriorly.
The proximal third of the ureter (and renal pelvis) can be reached with minimal muscle trauma through the thoracolumbar fascia lateral to the sacrospinalis and quadratus lumborum muscles. In terms of postoperative pain and morbidity, this incision is superior to all other lumbotomies. The 12th rib above and the iliac crest below limit exposure of the kidney and midureter. Therefore, the ideal stone for this approach should be one that is firmly embedded in the upper third of the ureter or at the ureteropelvic junction.
The patient is placed in the lateral recumbent position, with approximately 15-degree anterior rotation, and the table is flexed at the tip of the 12th rib. Simultaneous bilateral surgery may be performed with the patient prone.10 The most commonly used access6 utilizes an oblique skin incision parallel and 3 cm lateral to the erector trunci, from the 12th rib down to the iliac crest . Fat and subcutaneous tissue are divided until the lateral fibers of the latissimus dorsi are exposed. The muscle is split to expose the subjacent 12th rib. The posterior leaf of the lumbodorsal fascia is divided in the line of the skin incision, and the lateral margin of the sacrospinalis muscle so exposed is retracted medially. The middle layer of the thoracolumbar fascia is then seen and incised somewhat lateral to the fleshy belly of the sacrospinalis muscle. The lateral border of the quadratus lumborum now comes into view and may be retracted with a hook toward the vertebral column. The deep layer of the thoracolumbar fascia is exposed and opened, care being exercised to spare the twelfth subcostal nerve and the iliohypogastric nerve coursing obliquely and laterally on its deep aspect. Gerota’s fascia is incised, and the perirenal fat is divided by blunt dissection to expose the renal pelvis. In a modification,4 the incision runs from a point three fingerbreadths lateral to the dorsal spines to the junction of the middle and anterior third of the iliac crest. The lower parts of the latissimus dorsi and the serratus posterior inferior and the costovertebral ligament are divided, and the middle and deep leaves of the thoracolumbar fascia are split. A Finochiettio rib retractor is inserted to expose the field.
The distal half of the ureter is best approached by a suprainguinal extraperitoneal incision. The patient is in a prone position with the ipsilateral flank supported by a cushion. Depending on the exposure needed, the skin is incised in an oblique direction along a line from the pubic tubercle upward to a point about two fingerbreadths anterior to the superior iliac crest. The external oblique abdominal muscles and the transversalis fascia are divided with cutting diathermy in the same direction. After ligation and transection of the epigastric vessels, the peritoneal fold is reflected medially to expose the ureter. It can be identified without problems either where it crosses the common iliac artery or where it runs immediately below the obliterated umbilical artery. The latter structure is routinely divided and ligated.
With stones in the distal third of the ureter, a urethral catheter should routinely be placed to keep the bladder empty during the procedure.
Once the ureter is identified, the stone is located by palpation, carefully avoiding any milking movements that could dislocate it. Without mobilizing the ureter, it is snared with vessel loops just above and below the stone. The ureteral wall is incised with a scalpel directly onto the stone in a longitudinal direction. As soon as the mucosa is opened, the incision is enlarged with angulated scissors so that the stone can be extracted with nerve hooks. The ureter is then probed in both directions with a soft ureteral catheter to ascertain complete stone removal and is irrigated copiously.
With the slightest possibility of obstruction, extravasation, or difficult closure, a self-retaining stent is inserted, taking care to position the two ends properly in the bladder and renal pelvis. A standard double-J stent can usually be inserted from the ureterotomy. Because the distal segment of the ureter is, in general, more difficult to negotiate, especially after previous endoscopic maneuvers, it is intubated first. By reversing the stent, i.e., advancing the blunted, closed tip of the stent, which is otherwise advanced up to the kidney, down to the bladder, the ureterovesical junction can usually be passed. The guide wire is then removed, and the stent is advanced further down the ureter until it almost disappears in the ureterotomy. Its upper end can now be straightened and advanced up into the renal pelvis. If the proximal corner of the ureteric incision is elevated with a nerve hook during this procedure, this rarely causes problems. It is important to note the markings on the stent for correct placement. To ascertain that the distal end of the stent is in the bladder, indigo carmine can be administered through the urethral catheter; it should reflux freely into ureter and stent. Intraoperative fluoroscopy offers a more elegant alternative.
If any problems are encountered in intubating the ureter, the ureter should be inspected with a thin flexible ureteroscope inserted through the ureterotomy to avoid missing an additional ureteric stone. Any additional stone is either removed through a second ureterotomy or, preferably, by endoscopic lithotripsy. A guide wire is then advanced under endoscopic control down into the bladder, and the stent is inserted over it. Problems in the ureter proximal to the incision are handled in a similar manner, but this segment of the ureter is usually dilated and therefore easier to engage.
Whenever self-retaining stents are used, the patient should routinely be subjected to a flexible cystoscopy at the end of the procedure to be certain the vesical end of the stent is indeed in the bladder.
The ureterotomy is closed with one to three interrupted sutures of 5-0 chromic catgut. The sutures should grasp only the superficial seromuscular layers to approximate the ureteric wall rather than achieving watertight closure. If placed too tight or too deep, they may compromise ureteric blood supply and promote leakage. Obstructing sutures have a similar effect. Whenever closure is difficult because of scarring, it is safer not to close the ureterotomy at all and to stent the ureter. The site of the ureterotomy should be covered with retroperitoneal fat or an omental flap.
Every ureterotomy has to be drained precisely. We routinely use a No. 21 tube drain of silicone rubber with one or two side holes, which is brought out through all layers of the abdominal wall via a separate stab incision lateral to the lower end of the incision. The tip of the drain must be in a dependent position to the ureter-otomy, but not in the immediate vicinity or in contact with the ureter. If the ureter was approached transperitoneally, it should be drained through the retroperitoneum. The wound is closed in layers with absorbable suture material.
Postoperatively, patients are mobilized within 24 hours, with analgesics administered generously as needed. Antibiotics are given only with proven infection and according to appropriate sensitivity testing. The patients are well hydrated, with intravenous fluid replacement in the first two postoperative days. Especially after lumbar ureterolithotomy, bowel function may take 2 to 3 days to normalize, and an enema and even cholinergic agents may be needed.
The wound drain should not be removed before the fourth or fifth postoperative day. Prolonged discharge of urine from the drain is usually caused by impaired drainage caused by a missed calculus, clot, or ureteral obstruction. Occasionally leakage results from incorrect positioning of the tip of the drain immediately adjacent to the ureterotomy. Careful retraction of the drain by 1 to 2 cm then rapidly dries up the wound. If urine leaks from the drain longer than 5 days, an indwelling ureteric stent should be inserted. Permanent urinary fistulas are extremely rare and, when present, almost always result from obstruction below the level of surgery.
Urinary extravasation may cause severe problems if the wound is improperly drained because the drain either was not placed in a dependent position or was removed too early. Urinoma formation is usually heralded by fever and flank pain but may occur inconspicuously. A high degree of suspicion should therefore be directed toward this potential complication. Any unexplained fever, flank pain, or delayed healing should be investigated immediately by ultrasonography, an antegrade pyelogram (if the nephrostomy is still in place), or excretory urography with delayed films. The situation can usually be corrected by draining the kidney with an indwelling stent or a nephrostomy and by draining the urinoma percutaneously.
In the pre-SWL era, the most frustrating complication of any stone operation was the retained calculus. Although the availability of SWL should still not be an excuse for a less careful attempt at complete stone removal once open surgery is decided on, retained stones can be treated in this manner highly successfully some days after the operation. Likewise, if a calculus below the level of surgery was overseen and resulted in obstruction and/or extravasation, it can be treated endoscopically or by SWL, just as any other ureteral stone in the immediate postoperative period.