Prune Belly Syndrome and Urology
Management of the child with prune belly syndrome (PBS) has posed a significant amount of trouble to the pediatric urologist.
Some authors have called for conservative management of the urinary tract in these boys. In contrast, others have advocated an aggressive approach to the management of these patients, operating on them at ten days of life. At present, no definitive timing for therapy has been substantiated one way or the other. What we have been able to see is that prune belly syndrome can present with a spectrum of abnormalities ranging from the stillborn infant with severe urogenital and pulmonary problems to the child with little, if any, urological abnormalities requiring no therapy other than orchidopexies to correct the undescended testes. It appears that the decision to intervene in managing the urinary tract of these children should be based on the clinical presentation and not solely on radiographic appearance.
The literature contains little controversy about the present management of the undescended testes in these children. If controversy or confusion arises, it concerns the optimal timing and type of orchidopexy surgery. Similarly, there are several camps regarding the management of abdominal wall abnormalities. Some advocate no surgical reconstruction of the abdominal wall. In contrast, others advocate surgical reconstruction, and this group is divided into two factions advocating different abdominal wall reconstruction techniques.
The surgical management of the prune belly patient is not suited for the journeyman pediatric urologist. Still, it is best left to someone with experience managing these tricky patients. These children can present with a myriad of renal, ureteral, and urethral abnormalities.
Obstruction and/or upper urinary tract dilatation is not a rare occurrence in these children. Occasionally, the site of obstruction can vary from as high up in the pelvo-ureteral junction area to as far down as the prostatic membranous urethra. Careful radiologic evaluation of these children is essential before committing to any diverting procedure. Careful observation of urinary output and electrolytes is critical in the early newborn. A rise in BUN and creatinine associated with decreased urine output indicates obstruction. Radiologic studies should be obtained in the newborn period, regardless of whether obstruction is present. The first study that should be obtained is a renal and bladder ultrasound, a non-invasive procedure that can be used later on to follow the child's progress non-invasively. A contrast-voiding cystourethrogram should also be obtained to delineate the prostate-membranous urethra, the bladder, and the presence of a urachal remnant. Also, vesicoureteral reflux can be ruled out at this time, thereby indicating that the child should be placed on antibiotic prophylaxis. If there should be any indication that there is some upper tract dilatation or obstruction, then the child should have a renal Hippuran or DTPA study performed. Should there only be the presence of megaureter, megacystis, and prostatic abnormalities but no evidence of obstruction and no reflux, conservative management at this point is best indicated, and the child should be observed and followed closely.
Undescended testis
The management of the undescended testis in the patient with prune belly syndrome is something that should be left to the experienced pediatric urologist. In some instances, the boys will not require any urologic work, and these testis can be brought down using laparoscopic techniques. This reduces the morbidity associated with intraabdominal surgery to bring the testis down. Dr. Franco has reconstructed several boys using this technique with superior results. In other cases, the testis can be brought down during open surgery to reconstruct the urinary tract.
Abdominal Wall Reconstruction
Abdominal wall reconstruction is performed in most boys to improve respiratory function and for cosmetic reasons. There have been several innovations in abdominal wall reconstruction over the years. The Monfort and Ehrlich variations of Randolph's operation have improved results with decreased morbidity and the ability to preserve the Umbilicus. Firlit and Franco have described a new technique that allows for improved results over these techniques without opening the abdominal cavity. Most recently, Franco has modified this technique to obtain even better results by using laparoscopic guidance to ensure that wall tension and cosmetic results will persist postoperatively. These innovations have reduced the morbidity of abdominal wall reconstruction significantly.
Obstruction at the ureteropelvic junction
Obstruction at the ureteropelvic junction has been observed in patients with prune belly syndrome. In some cases, making the diagnosis can be difficult, but the placement of a percutaneous nephrostomy can confirm the diagnosis. This procedure can be done under ultrasound guidance with relative ease in a dilated system. It also provides the opportunity to obtain a renal biopsy in these patients, which could help later manage the urinary tract. Placement of a percutaneous nephrostomy provides the surgeon with several options. He can confirm his diagnosis of UPJ obstruction. He can decompress the urinary tract in a sick child or in a child who is too small to undergo reconstructive surgery at this time safely. 3. It allows the surgeon to evaluate the renal function of the obstructed unit. It allows the surgeon to obtain a renal biopsy at the time of placement of the percutaneous nephrostomy.
If conditions are right and the child is stable, a standard pyeloplasty can be performed to manage the obstructed UPJ. The surgeon should be meticulous in his dissection of the upper ureter, keeping in mind that he should try to preserve the proximal ureteral blood supply as much as possible if this child should later need ureteral tapering or reimplantation. Recent studies indicate that the more proximal the ureter is, the more anatomically normal the portion of the ureter, while the distal lower ureter is abnormal in several ways. Histologically, the ureter has a smooth muscle deficiency, fibrous degeneration, and poor blood supply. There is also a reported decrease in nerve plexuses with irregularity in degenerating nonmyelinated Schwann fibers. In patients with supravesical obstruction and functional vesical obstruction, cutaneous pyelostomy has been recommended as the preferred means of diverting the ureter and the pelvis in these patients for several reasons. It is believed that the proximal ureter is compromised less in this manner than by doing a high loop ureterostomy, as had been previously performed in these patients. Also, by performing a pyelostomy, we avoid the undesirability of attaching the ureters to the abdominal wall, thereby preventing the common problem of a prolapsed ureterostomy. If one were forced to do a ureterostomy, one would tend to opt to use the distal ureter since this ureter would most likely be discarded at a later date when the child is reconstructed. Cutaneous pyelostomy still carries the risk of resultant scarring from excessive dissection, which may be required to take down the pyelostomy at a later stage. At the time of reconstruction, one could be left in a precarious position if ureteral tapering or reimplantation was necessary.
These problems have been overcome most recently with the increasing use of percutaneous nephrostomy drainage and vesicostomy to drain the upper tracts. Some believe that vesicostomy can decompress the upper tracts in these children, just as well as high diversion. Subsequently, with the introduction of these two procedures, the use of high diversion has declined significantly over the last few years, making reconstruction in these children easier.
Infravesical obstruction or obstruction at the prostatic urethra was initially thought to be due to a Type I valve. This theory has been replaced by a new thinking in which the obstruction is felt to be caused by severe angulation at the prostatic and membranous urethral junction. This may be possibly due to a lack of striated muscle in the membranous urethra or the urogenital diaphragm or a ring of obstructive tissue acting as a flap valve due to hypoplasia of the prostate, creating a ballooning of the prostatic urethra In these patient's, studies have also shown that there is a reduction in the smooth muscle in the prostate with an increase in the connective tissue content which has been thought to lead to a functional obstruction. This abnormality in the prostatic urethra can be similar to a valve created by the anterior urethral diverticulum. Douglas Stephens describes this configuration as a Type IV valve in prune belly patients in which the dilated prostatic urethra joins the membranous urethra in various configurations, causing obstruction. However, none of these theories have been supported by urodynamic studies, which fail to demonstrate either mechanical or functional outlet obstruction in most cases.
Nevertheless, patients with documented obstruction can be managed by several means. The simplest and best is using a Blocksom vesicostomy in the early newborn period. The vesicostomy must be created by bringing the bladder dome to the skin. By performing the vesicostomy in this manner, one can prevent the resultant herniation of the bladder in an improperly created vesicostomy. Herniation of the bladder is quite prevalent in patients with prune belly syndrome since the bladder is quite large and redundant.
A patent urachus is frequently found in patients with urethral obstruction, which means that these patients survived. It is documented that the early deaths in prune belly syndrome are usually seen in patients with urethral obstruction without a patent urachus. In these patients, once a vesicostomy is performed, the surgeon should try to identify the urachus and ligate it at that time.
Posterior urethral valves are occasionally seen in patients with prune belly syndrome, which is best managed by transurethral resection. The use of sphincterotomy, transurethral resection of the bladder neck, or internal urethrotomy has been advocated by some as a means of controlling the functionally obstructed system. Snyder and associates believe that judicious use of urethrotomy can lower urethral resistance and improve voiding dynamics without causing incontinence. Opinions regarding using these modalities are mixed when few actual results have been seen. Firlit et al. have used soft catheter dilatation as a means of dilating the functionally obstructed urethra in patients with prune belly syndrome. They have left soft indwelling catheters for extended periods while gradually increasing the catheter size until they achieve the desired caliber. Radiologic and functional results are needed.
Megaureters and Reflux
The prune belly syndrome is characterized by elongated, dilated, and tortuous megaureters. Eighty-one percent of the patients have these ureteral abnormalities, and vesicoureteral reflux is common in them. Advocates of the conservative management modality argue that in a non-obstructive system with present suppressive therapy, there is no need to intervene.
The group that argues for aggressive therapy in prune belly patients points to Waldbaum's and Marshall's review of 56 patients in which seventy percent died, and sixteen percent were gravely ill. He argues the position of aggressive therapy when he states., "The purpose of the upper tract is to transport urine, not to store it." It is felt that even with aggressive antibiotic therapy, urinary stasis and repeat infections lead to the inevitable loss of renal function. Be it as it may, ureteral reimplantation in prune belly patients can be pretty tricky and is not infrequently fraught with complications. To attest to this, we have seen several patients previously reimplanted who developed ureteral strictures of the distal reimplanted ureters and required re-reimplantation. As well there are reports in the literature which have a documented ureteral stenosis rate as high as forty percent in tapered ureters.
Ureteral reimplantation in this group of patients requires an aggressive approach to removing as much of the abnormal distal ureter and preserving the blood supply to the proximal ureter. Some authors advocate shortening, tapering, and reimplanting the better of the two ureters with a long tunnel, psoas hitch, and draining of the contralateral side with a TUU. This is because the prune belly patient's bladder can be pretty thick and fibrous, making it challenging to place too long reimplants. Ureters are preferentially tapered over an eight or 10-French red rubber catheter, excising excess tissue. Most recently, Starr reimplants using the folding cross re-implantation. He has not had an episode of either obstruction or reflux. It is possible that with this technique, the critical blood supply to the distal ureter is not interrupted as with the traditional excisions.
Megacystis
Megacystis in prune belly patients is typically described. The bladder is routinely enlarged; although trabeculations are rarely present and muscular hypertrophy is inconsistent, it can be fixed to the umbilicus via urachus, giving it an hourglass radiographical configuration. Bladder voiding pressures are frequently close to normal, and there is an insignificant residual urine volume. Snyder describes that there is typically a shift to the right, with some prunes capable of voiding perfectly normally. Some authors feel that reducing cystoplasty can improve detrusor force. It is thought that the shape of the bladder in prune belly syndrome patients can lead to unbalanced voiding. It is believed that decreased bladder capacity would lead to increased detrusor efficiency based on LaPlace's law. Reduction cystoplasty has met with mixed reviews. It is generally recognized that reduction cystoplasty is not necessary as a primary procedure but may be helpful. It is frequently performed at the time of ureteral reimplantation and tapering.