Prune Belly Syndrome and Urology
Introduction
Management of the child with prune belly syndrome (PBS) has posed a significant amount of trouble to the pediatric urologist. There have been calls for conservative management of the urinary tract in these boys by some authors while others have advocated an aggressive approach to the management of these patients, operating on them at ten days of life. At the present time, 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 the management of the urinary tract of these children should be based on the clinical presentation and not solely on radiographic appearance.
There is little controversy in the literature as to the present management of the undescended testes in these children. If controversy or confusion arises, it is to the optimal timing for the surgery for the orchidopexy as well the type of orchidopexy to be performed. Similarly, the management of the abdominal wall abnormalities has several camps with some going for no surgical reconstruction of the abdominal wall while others advocate surgical reconstruction and this group being divided amongst two separate factions advocating different techniques of abdominal wall reconstruction.
The surgical management of the prune belly patient is not suited for the journeyman pediatric urologist, but it is best left to someone with experience in managing these quite difficult 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 one's self to any type of diverting procedure. Careful observation of urinary output and electrolytes is essential in the early newborn. A rise in BUN and creatinine associated with decreased urine output is an indicator of obstruction. Radiologic studies should be obtained in the newborn period, regardless of whether obstruction is present or not. The first study that should be obtained is a renal and bladder ultrasound, which is a non-invasive procedure and 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 as well as the bladder and the presence of an urachal remnant. Also, vesico-ureteral 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 at all 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 the 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 at the time of open surgery for the reconstruction of the urinary tract.
Abdominal Wall Reconstruction
Abdominal wall reconstruction is performed in most boys to improve respiratory function as well as 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, which allows for improved results over these techniques without opening the abdominal cavity. Most recently Franco has modified this technique further to obtain even better results by using laparoscopic guidance to assure that wall tension and cosmetic results will be persistent postoperatively. These new innovations have reduced the morbidity of abdominal wall reconstruction significantly.
Obstruction at the uretero-pelvic junction
Obstruction at the uretero-pelvic junction has been observed in patients with prune belly syndrome. In some cases, making the diagnosis can be difficult and diagnosis can be confirmed by the placement of a percutaneous nephrostomy. 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 with the later management of 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 that is too small to safely undergo reconstructive surgery at this time. 3. It allows the surgeon to evaluate the renal function of the obstructed unit. It provides the surgeon with the opportunity 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 as another means of managing 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 in the event that this child should later need ureteral tapering or reimplantation. Recent studies indicate that the more proximal ureter is the more anatomically normal portion of the ureter, while the more distal lower ureter is abnormal in several ways. Histologically, the ureter has a smooth muscle deficiency with fibrous degeneration and a poor blood supply. There is also a reported decrease in nerve plexuses with irregularity in degeneration of nonmyelinated Schwann fibers. In patients that may have supravesical obstruction as well as 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 an 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. One then at the time of reconstruction could be left in a precarious position if ureteral tapering or reimplantation was necessary.
These problems have most recently been overcome with the increasing use of percutaneous nephrostomy drainage and with the use of vesicostomy as a means of draining the upper tracts. It is a belief of some 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 and has made reconstruction in these children easier.
Infravesical obstruction or obstruction at the prostatic urethra was originally 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 shown also 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 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, all of these theories have not been supported by urodynamic studies which fail to demonstrate either mechanical or functional outlet obstruction in the majority of the cases. Never the less, the patient with documented obstruction can be managed by several means. The simplest and best is the use of a Blocksom vesicostomy in the early newborn period. It is essential that the vesicostomy be created by bringing the dome of the bladder out 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 can be frequently found in patients with urethral obstruction, this being the means that these patients were able to survive, since 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 and the valves are 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 managing 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 are mixed regarding the use of these modalities 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 of time while they gradually increase the size of the catheter until they achieve the desired caliber Radiologic and functional results needed.
Megaureters and Reflux
The prune belly syndrome is characterized by elongated, dilated and tortuous megaureters. These ureteral abnormalities are present in eighty-one percent of the patients. Vesicoureteral reflux is common in these patients. 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. as well 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 inevitable loss of renal function. Be it as it may, ureteral reimplantation in prune belly patients can be quite difficult 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 at removing as much of the abnormal distal ureter and preserving the blood supply to the proximal ureter. Some authors advocate that by shortening, tapering, and reimplanting the better of the two ureters with a long tunnel and psoas hitch and a draining of the contralateral side with a TUU. The reason for this is that the prune belly patients bladder can be quite thick and fibrous, thereby making it difficult to place too good long reimplants. Ureters are preferentially tapered over an 8 or a 10 French red rubber catheter and excess tissue is excised. Most recently, Starr reimplants using the folding cross re-implantation. He has not had an episode of either obstruction of 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 the bladder can be fixed to the umbilicus via urachus, giving it an hourglass configuration radiographically. Bladder voiding pressures frequently are 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 normal Some authors feel that reduction cystoplasty can improve detrusor force 67 It is thought that the shape of the bladder in prune belly syndrome patients can lead to unbalanced voiding It is thought 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 useful and is frequently performed at the time of ureteral reimplantation and tapering.