URETEROPELVIC JUNCTION OBSTRUCTION IN CHILDREN

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URETEROPELVIC JUNCTION OBSTRUCTION

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URETEROPELVIC J U N C T I O N OBSTRUCTION IN CHILDREN Unique Considerations for Open Operative Intervention A. Michele Ward, MD, Robert Kay, MD, and Jonathan H. Ross, MD

Ureteropelvic junction (UPJ) obstruction is the most common cause of hydronephrosis in neonates and children. Often discovered antenatally on ultrasound or presenting with symptoms later in childhood, UPJ obstruction may lead to progressive renal deterioration. Although several series have suggested a role for a nonoperative approach to diagnosed UPJ obstruction, surgery remains the treatment of choice for true functionally significant obstruction at the UPJ.5,16, *O The treatment of obstructive uropathy in children is different from that in adults. The approach to surgery and the variables in surgery are distinctly different from that in adults and must be individualized for each infant and child. Distinguishing factors in the child include the overall and renal anatomy, the etiology of the UPJ obstruction, the presence or absence of crossing vessels, and the technical difficulty with stents. For these reasons, the urologist is faced with considerations unique to each child undergoing repair of UPJ obstruction. This article discusses the variables in the operative repair of UPJ obstruction in children, including the surgical approach, the appropriate use of stents and nephrostomy tubes, and the controversies in perioperative imaging, such as the role of retrograde pyelography.

IMAGING

Generally, the diagnosis of a UPJ obstruction is straightforward. In the neonatal period, if the hydronephrosis is seen antenatally and if ultrasonography is performed initially in the first week postnatally to confirm hydronephrosis, the patient should be started on a regimen of prophylactic antibiotics, usually, amoxicillin at 25 mg/kg/day. At 1 month of age, repeat ultrasonography and voiding cystourethrography should be performed. If imaging suggests UPJ obstruction as demonstrated by the absence of reflux on the cystogram and the absence of a dilated ureter on renal ultrasound, a renal scan should be performed. Generally, a diuretic MAG-3 or DTPA renal scan is performed. If there is a significant delay in excretion, the diagnosis of UPJ obstruction is essentially confirmed. A unique consideration in children in comparison with adults is the evaluation of the ureter. In general, adults undergo intravenous pyelography preoperatively or retrograde pyelography at the time of surgery to evaluate the ureter and to rule out other disease, such as strictures, stones, or tumors. In contrast, in children, the use of retrograde pyelography is controversial. The advantage of retrograde pyelography is that it

From the Section of Pediatric Urology, Cleveland Clinic Foundation, Cleveland, Ohio

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allows complete visualization of the urinary tract and therefore complete confidence on exploring the patient. If there is a proximal ureteral stricture or distal obstruction, the appropriate incision may be made for the planned surgical procedure. Proximal ureteral strictures can be managed through a flank incision, but a missed distal ureteral obstruction would be a significant problem. The need to instrument the distal ureter in a male child is associated with potential, albeit uncommon, complications. Urethral injury is rare but possible. If the patient is undergoing a tubeless diversion, manipulation of the distal ureter should be avoided to minimize edema and thereby poor drainage resulting from temporary obstruction. Significant edema or difficulty with a distal ureter could lead to significant extravasation, particularly if there is no diversion proximally. Although retrograde pyelography is significantly easier in female infants, the same issues regarding distal obstruction apply. Perhaps the more important question is whether retrograde pyelography is even necessary in a child. In one series of 108 children in which only one retrograde pyelogram was obtained, routine retrograde pyelograms were found to be unnecessary to find the level of obstruction or concomitant disease.21That series, as well as the personal experience of the authors suggests that when examination is performed by an experienced ultrasonographer who can identify ureteral dilatation, retrograde pyelography is not generally necessary, and a definitive diagnosis may be made by ultrasonography and a diuretic scan. If the level of obstruction is more distal than the UPJ, a dilated ureter should be seen on both ultrasound and the renal scan. In all patients,

the need for retrograde pyelography should be individualized. If the ultrasound or renogram is not clear, either intravenous pyelography or retrograde pyelography can be performed to delineate the pathology. OPERATIVE APPROACH

Four criteria for success in the repair of a UPJ obstruction were defined by Foley" in 1937 as follows: (1)formation of a funnel, (2) dependent drainage, (3) water-tight anastomosis, and (4) tension-free anastomosis. Although the classic Anderson-Hynes dismembered pyeloplasty is the most popular procedure, pyeloureteroplasty techniques have been described in detail which fulfill these criteria successfully.',h, ',x, 22 The surgical exposure to the kidney is a critical factor in achieving an excellent result and fulfilling Foley's criteria. Appropriate exposure to an obstructed UPJ in children may be gained through several different incisions. A flank incision, posterior incision, or anterior incision may all give access to the obstructed UPJ and allow the surgeon adequate visualization for surgical repair. The goal is to obtain adequate exposure with the least morbidity; in children, this can generally be acquired through any of the previous approaches. The flank incision offers both advantages and disadvantages in the child. With the flank incision, much like in an adult, the child is placed at a 75- to 90-degree angle on the table. However, unlike in an adult for whom the table must be used to flex the patient, a small infant can be placed over a rolled towel to allow separation of the iliac crest from the ribs (Fig. 1). Also in contrast to adults, it is Incision

Iliac crest

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Figure 1. The infanuchild is positioned on the table at a 75"-90" angle. Folded towels are used to flex the child.

URETEROPELVIC JUNCTION OBSTRUCTION IN CHILDREN

not necessary to remove a rib in small infants. A small transverse incision can be used to enter the retroperitoneum, and, with minimal mobilization, visualization of the UPJ is excellent. Advantages of the flank incision include an extraperitoneal approach, excellent exposure of the UPJ with minimal mobilization of the kidney, and minimal morbidity to the child. A possible disadvantage of this approach includes the need for some mobilization of the lower pole of the kidney and proximal ureter for adequate visualization of the UPJ, particularly in the setting of moderate hydronephrosis. A flank position is the authors' preferred approach for dismembered pyeloplasty because of its excellent, reproducible results. In addition, a major advantage of the flank incision is the ability to extend it to deal with any unexpected anatomic abnormality that may be encountered. If the UPJ obstruction is associated with a proximal stricture, complete mobilization of kidney and ureter generally allows complete bridging of the defect to ensure successful repair. In addition, unexpected findings, such as crossing vessels, unrecognized duplicated systems, malrotated kidneys, or other unique anatomic abnormalities, may all be dealt with through the flank approach without significant difficulty. A posterior lumbotomy incision is another approach preferred by others.I3,I R , 23, 24 This approach offers the most direct surgical exposure of the UPJ, at least in normally rotated kidneys.I3 Because the kidney is retroperitoneal and the UPJ obstruction often posterior, it is natural to assume that the posterior approach will allow the surgeon the most direct path to the anatomic abnormality. Further advantages of posterior lumbotomy incisions include a cosmetically acceptable, relatively short incision (Fig. 2A, B). In addition, bilateral repairs can be performed without repositioning the patient. Posterior lumbotomy requires minimal mobilization of the ureter and pelvis, thereby protecting the delicate blood supply to the ureter. Sheldon and co-workers2' reviewed 51 pyeloplasties in 1992 and concluded that posterior lumbotomy was replacing the flank approach as the preferred method of exposure. There are, however, disadvantages to the dorsal lumbotomy incision which relate primarily to limited exposure. The key to the success of any surgical approach in is adequate exposure. Clearly, one of the major disadvantages of .posterior lumbotomy is the small incision and the inability

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to extend it beyond certain parameters such as the ribs or iliac crest. If there are associated anatomic abnormalities such as a malrotated kidney or a proximal ureteral stricture, or if it becomes necessary to further mobilize the kidney or ureter, the problem may be difficult to manage through posterior lumbotomy. Although there are many proponents of posterior lumbotomy in children, the authors have used it only selectively because of concerns regarding the potential disadvantages mentioned previously. An anterior extraperitoneal incision is attractive in children for reasons similar to those mentioned for posterior lumbotomy. The anterior extraperitoneal approach involves a relatively small incision that directly places the surgeon in an anatomically correct position, thereby minimizing the need to mobilize the kidney or ureter. Because a UPJ obstruction is anatomically medial to the kidney, an anterior approach allows direct exposure of the area without the need for excessive mobilization. In addition, an anterior extraperitoneal approach may be used for bilateral UPJ repair without repositioning the patient. Disadvantages may include more difficult mobilization and the need for a further, wider incision in some cases. Although the anterior extraperitoneal incision can be extended intraperitoneally at any time, this is generally not desirable. The patient is placed supine on the table, at times using a small roll under the back to raise the flank to 30 degrees (Fig. 3). The anterior extraperitoneal incision has some of the advantages of both a true flank incision and a transperitoneal incision and remains the approach preferred by some pediatric urologists. Disadvantages include the need to mobilize the peritoneum and, occasionally, the need for a larger incision to visualize adequately the UPJ. The repair, however, remains extraperitoneal, which is a major advantage in comparison with the classic anterior transperitoneal incision. An anterior transperitoneal incision is rarely used in children. The potential advantage is excellent exposure to the UPJ in an anatomic position. Disadvantages, however, are the required opening of the peritoneum and mobilization of bowel, associated with subsequent morbidity. This includes a high incidence of bowel obstruction, particularly in children less than 1 year of age. Therefore, a transperitoneal approach to the management of UPJ obstruction is generally contraindicated in ~ h i l d r e n . ~

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Incision

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Figure 2. A, The infanuchild is placed in the prone position with a towel under the abdomen. A vertical incision on the affected side is parallel to the sacrospinalis. B, The anatomic axial image of proposed surgical incision through a posterior lumbotomy is shown.

The endoscopic approach to UPJ obstruction has gained wide acceptance in adults, and there is increasing experience in children.' In large series of adult patients, success rates are approaching those reported for open Incision

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Figure 3. The infantkhild supine is placed supine with a towel under the patient. A transverse extraperitoneal or intraperitoneal incision is made in the subcostal region.

pyeloplasty.'2 One of the first approaches to endoscopic treatment of UPJ in children was reported by King and c o - ~ o r k e r s 'in ~ 1984. They performed endoscopic repair of two postoperative obstructions through a preexisting nephrostomy tract with a 50% success rate.I5 For years, however, the lack of adequate instrumentation has limited access to the UPJ in children; thus, open surgery has remained the treatment of choice. More recently, case reports and small series of children with UPJ obstruction, both primary or secondary, have been described in which the patients have been treated successfully with fluoroscopic Acucise endopyelotomy (Applied Medical Resources, Laguna Hills, CA), antegrade endopyelotomy, retrograde balloon dilatation, or laparoscopic repair.4,lo, 19, 25, 26, 27 Bolton and co-workersq report that the short-

URETEROPELVIC JUNCTION OBSTRUCTION IN CHILDREN

term results of Acucise endopyelotomy in two children were satisfactory and without acute complications. In another study, five children successfully underwent percutaneous antegrade endopyelotomy for the treatment of secondary UPJ obstruction and avoided an open repeat pyeloplasty.I0Retrograde balloon dilatation was unsuccessful in treating primary UPJ obstruction in 9 of 17 patients (53%)in one series, and the patients required open p y e l o p l a ~ t yHowever, .~~ Tan and co-workers26reported a successful outcome in 7 of 10 patients with this procedure. They also treated six children by laparoscopic pyeloplasty, with one case requiring open surgery and five having improved or normal drainage on f o l l o ~ - ~In p .the ~ ~previous reports, the investigators concluded that these minimally invasive approaches to pediatric UPJ obstruction are associated with encouraging results, and that further investigation and the performance of prospective studies with long-term follow-up are warranted. The indications techniques, and results of endourologic management of UPJ obstruction in children are detailed elsewhere in this issue. Special consideration should be given to the child undergoing repeat pyeloplasty. A key factor in the success of reoperation is to gain anatomic exposure that leaves a wide range of surgical repairs possible. This includes repeat pyeloplasty, ureterocalicostomy, ileal ureter procedures, or even nephrectomy. The best approach is a large incision that allows the performance of any of the previous operations. In most cases, a large flank incision will allow the surgeon to repeat the pyeloplasty or to perform a ureterocalicostomy. Although ileal ureteral replacement is difficult through this incision, it can be performed. In most cases, however, an anterior transperitoneal incision would be more appropriate. As such, if one feels the probability of performing ileal ureter replacement is great, this must be taken into consideration when deciding on the surgical approach for the child. Generally, a long, flank incision with complete mobilization of the kidney and ureter allows excellent exposure and the potential for excellent success rates, even in challenging repeat pyeloplasties. OPERATIVE STENTS AND NEPHROSTOMY TUBES

The need for placing stents intraoperatively in children undergoing repair of an ob-

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structed UPJ is controversial. Hendren and co-w~rkers'~ have suggested that a stent is usually unnecessary, although they had no direct problems when leaving one. Advantages of urinary diversion include minimizing leakage, thereby reducing peripelvic inflammation which can subsequently lead to fibrosis and recurrent obstruction. Disadvantages include technical difficulties in placing a nephrostomy tube or stent and postoperative management, including their subsequent removal. Diversion should generally be external, because internal diversion in children requires an anesthetic to remove the stent cystoscopically. Such instrumentation is an additional risk in male patients. The use of stents is indicated in children with poor renal function, in those undergoing repeat pyeloplasty, in children with solitary kidneys, and in those in whom significant renal pelvic tailoring is required. When nephrostomy tube drainage of the renal pelvis is required, a small Malecot catheter can be placed in a lower pole dilated calyxI4(Fig. 4). The authors prefer to place a small 5-F ureteral stent adjacent to the nephrostomy tube. The stent is generally removed on day 6 and the nephrostomy tube the next day. Other techniques include a stent-and-vent system (8-F Silastic feeding tube over a 4-F openended ureteral catheter) or KISS (kidney splint/stent) ~ y s t e m . ' ~ A study of 48 consecutive dismembered pyeloplasties performed in children to assess the benefits of the use of stents showed that children with stents had more febrile episodes, needed more antibiotics, and had longer hospital stays in comparison with children without stents.z However, another retrospective review of 63 pyeloplasties suggested that the routine use of ureteric stents may be beneficial; patients undergoing the nonstented UPJ repairs had longer hospital stays and urinary leakages, three (4.8%), of whom required reoperation.2R The authors recognize that the use of diversion is an individual decision on the part of the surgeon. Several guidelines are followed when stents are placed during dismembered pyeloplasty in the authors' patients. In general, stents are not required. A stent is indicated in the patient with infection, in the presence of stone disease, in significant pelvis tailoring, in the procedure associated with technical difficulties, in the patient with a solitary kidney, and in other unusual anatomic encounters.

Figure 4. A 12F Malecot nephrostorny tube and a 5F silastic pyeloureteral catheter are placed in the renal pelvis exiting the lower pole calyx.

SUMMARY

The treatment of UPJ obstruction in children should be approached in a fashion that recognizes the differences between children and adults. Radiographic definition of the urinary tract is different in children than in adults because of the size of the child and tec hn i ca 1 d i f fic u 1ties w i th instrument at ion. Retrograde pyelography, in general, is not necessary in children, although this decision must be indilridualized. The surgical incision should be chosen based on the size of the child and the unique considerations of indi\,idual renal anatomy and pathology, as well ‘1s the surgeon’s experience. In children, tubeless surgery may be performed with excellent results, however, diversion with nephrostomies and stents may be necessary in selected CdSt‘S.

With attention to technical details and the uniq~icconsiderations in children, the results of repair of the UPJ should be excellent and rep rod u cib le.

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Address reprint requests to Robert Kay, MD Section of Pediatric Urology Cleveland Clinic Foundation 9500 Euclid Avenue Cleveland, OH 44195