140

Prune-Belly Syndrome

Anthony A. Caldamone; Francisco Tibor Dénes

Questions

1.Common findings in the prune-belly syndrome include all of the following EXCEPT:

a.deficiency of abdominal wall musculature.

b.urinary tract dilatation.

c.palpable undescended testes.

d.urachal pseudodiverticulum.

e.vesicoureteral reflux.

2.Which of the following statements regarding the prognosis of patients with prune-belly syndrome is FALSE?

a.The patient will likely be infertile.

b.A substantial risk of renal failure exists.

c.Testicular descent will not occur spontaneously.

d.The male “pseudo-prune” phenotype is protected from renal failure.

e.Chronic constipation and ineffective cough may result from abdominal wall laxity.

3.Complications involving which of the following organ systems are most likely to threaten the early survival of an infant with prune-belly syndrome?

a.Cardiac

b.Renal

c.Pulmonary

d.Gastrointestinal

e.Endocrine

4.Ureteral dysfunction in prune-belly syndrome is related to all of the following EXCEPT:

a.ureteral dilatation with failure of luminal coaptation during peristalsis.

b.reduced smooth muscle tissue.

c.failure of propagation of an electrical conduction due to increased fibrous connective tissue.

d.more severe proximal ureteral dysfunction with failure to conduct a urinary bolus from the renal pelvis.

e.abnormal myofilament content in smooth muscle cells.

5.Urodynamic bladder evaluation in prune-belly syndrome is primarily characterized by bladder enlargement with:

a.elevated voiding pressures and detrusor-sphincter dyssynergia.

b.high-amplitude uninhibited contractions.

c.poorly contractile detrusor or myogenic failure.

d.poor compliance.

e.absent sensation.

6.The classic findings on prenatal ultrasound on prune-belly syndrome include all of the following EXCEPT:

a.ambiguous genitalia.

b.hydroureteronephrosis.

c.distended bladder.

d.early fetal ascites.

e.irregular abdominal wall circumferences.

7.A management strategy of observation in the prune-belly syndrome is strongly supported by which finding?

a.That spontaneous improvement in dilatation of the urinary tract generally occurs after puberty

b.That vesicoureteral reflux occurs at low pressures and does not represent a threat to renal parenchyma

c.That the risk of obstruction after ureteral reimplantation always outweighs the benefit

d.That operative risks in this patient population are excessive

e.None of the above

8.Which statement is most accurate when considering management of the lower urinary tract in the patient with prune-belly syndrome?

a.Reduction cystoplasty is indicated when bladder capacity becomes greater than expected for age.

b.Internal urethrotomy improves postvoid residual urine volumes without risk of incontinence.

c.Reduction cystoplasty permanently improves bladder dynamics.

d.Internal urethrotomy should be specifically based on pressure-flow studies.

e.Routine intermittent catheterization should be used to improve postvoid residual urine volumes in all patients.

9.Which statement regarding orchiopexy in the patient with prune-belly syndrome is TRUE?

a.It requires a microvascular testicular autotransplantation because of the high intra-abdominal position.

b.It maintains endocrine function but has no potential to preserve spermatogenesis.

c.It can be best accomplished by transperitoneal mobilization before 1 year of age.

d.It should never involve use of the Fowler-Stephens technique because of unreliability of the collateral testicular blood supply.

e.It is performed if spontaneous descent fails to occur by 2 years of age.

. The most appropriate indication for prenatal intervention in suspected prunebelly syndrome is:

a.oligohydramnios.

b.urinary ascites.

c.urethral atresia and progressive oligohydramnios.

d.pulmonary hypoplasia.

e.distended bladder.

. The most appropriate initial management of the newborn with prune-belly syndrome includes:

a.percutaneous drainage of the upper urinary tract after stabilization.

b.stabilization and then vesicostomy if anesthetic risk permits.

c.stabilization and then bilateral cutaneous ureterostomy if anesthetic risk permits.

d.evaluation of pulmonary status and voiding cystourethrogram to rule out posterior urethral valves and reflux.

e.evaluation of pulmonary status, renal ultrasonographic study, and prophylactic antibiotics.

. The prostatic urethra in prune-belly syndrome:

a.is dilated and associated with bladder neck hypertrophy on a voiding cystogram.

b.is sometimes associated with congenital urethral obstruction resulting in megalourethra.

c.is associated with a hypoplastic prostate with decreased epithelium and increased smooth muscle.

d.results in retrograde ejaculation.

e.is characterized by none of the above.

Answers

1.c. Palpable undescended testes. Bilateral cryptorchidism is a central feature of the syndrome, and in most patients both testes are intraabdominal, overlying the ureters at the pelvic brim near the sacroiliac level.

2.d. The male "pseudo-prune" phenotype is protected from renal failure.

Although it is exceptionally rare to encounter a normal urinary tract in association with the characteristic abdominal wall defect in a male, the converse is not unusual. Some patients (with pseudo-prune-belly syndrome) with a normal or relatively normal abdominal wall exhibit many or all of the internal urologic features. These features may include dysplastic or dysmorphic kidneys or dilated and tortuous ureters. One report noted eight boys with relatively mild external features of the syndrome, five of whom progressed to renal failure, evidence that these children remain vulnerable to renal deterioration.

3.c. Pulmonary. The most urgent matters are actually those concerned with cardiopulmonary function. Pulmonary complications including pulmonary hypoplasia, pneumomediastinum, pneumothorax, and cardiac abnormalities must be excluded.

4.d. More severe proximal ureteral dysfunction with failure to conduct a urinary bolus from the renal pelvis. The proximal ureter usually displays a more normal appearance, an important feature when considering corrective surgery.

5.c. Poorly contractile detrusor or myogenic failure. Usually, the cystometrogram reveals excellent detrusor compliance; the end-filling pressure assumes a normal value; and the bladder functions well as a reservoir. However, bladder sensation during filling is shifted to the right with a delayed first sensation to void, and bladder capacity may be more than double the normal volume. Less consistent and less favorable results are seen with the voiding profile. The compressor capabilities of the detrusor are diminished by the frequent presence of vesicoureteral reflux and reduced

detrusor contractility.

6.a. Ambiguous genitalia. The findings on prenatal ultrasound in prune-belly syndrome may not be diagnosed in all cases but would include hydronephrosis, an enlarged bladder, ascites presenting in the second trimester, and irregular abdominal wall circumference. Although external genital anomalies such as bilaterally undescended testes and megalourethra occur with prune-belly syndrome, these would not be detected on prenatal ultrasound as abnormalities of external genital development.

7.e. None of the above. The obvious implication of different studies was that a more aggressive approach was necessary to improve the fate of the infant with prune-belly syndrome. With the recognition that infection and progressive renal insufficiency are the factors that most often pose the greatest threat to quality of life and survival, surgical reconstruction to normalize the anatomy and function of the genitourinary tract was advocated. Early retailoring of the urinary system to reduce stasis and eliminate reflux or obstruction has included ureteral shortening, tapering and vesicoureteral reimplantation, and reduction cystoplasty. Reconstruction is best delayed until the child is approximately 3 months old, to allow for pulmonary maturation. This approach has been successful in achieving anatomic and functional improvement.

8.d. Internal urethrotomy should be specifically based on pressure-flow studies. Some initial improvement in voiding dynamics can be achieved by aggressive bladder remodeling. However, with long-term follow-up, there has been no evidence that this improvement is maintained, and excessive bladder volumes tend to recur with time. Internal urethrotomy is indicated in the rare patient with true anatomic urethral obstruction or in patients with urodynamic evidence of urethral obstruction by pressure-flow studies.

9.c. It can be best accomplished by transperitoneal mobilization before 1 year of age. Orchiopexy in all patients is now generally performed during infancy in an effort to maintain the germ cell population and protect spermatogenesis. In the neonate and in patients as old as 6 months, transabdominal complete mobilization of the spermatic cord almost always allows the testis to be positioned in the dependent portion of the scrotum without dividing the vascular portion of the spermatic cord. The

Fowler-Stephens technique for performing orchiopexy in patients with intraabdominal testes has become part of the standard urologic armamentarium.

. c. Urethral atresia and progressive oligohydramnios. Because most

hydronephrosis in prune-belly syndrome is well tolerated, its presence alone is not an indication for intervention. Similarly, oligohydramnios, pulmonary hypoplasia, distended bladder, and urinary ascites do not independently warrant prenatal intervention. The only situation with prune-belly syndrome that is potentially reversible is the pulmonary hypoplasia that is seen from urethral atresia and due to progressive oligohydramnios. Oligohydramnios that occurs early in the second trimester is generally indicative of severe renal dysplasia.

.e. Evaluation of pulmonary status, renal ultrasonographic study, and prophylactic antibiotics. The most urgent matters are those concerned with cardiopulmonary function. After stabilization, urologic evaluation proceeds with physical examination and ultrasonography. Imaging requiring

catheterization and the potential for introduction of bacteria should be avoided unless the results are necessary for immediate clinical decision making. Attention to sterile technique is crucial if invasive studies are performed. Once introduced, infection in a static system may be difficult to eradicate.

.d. Results in retrograde ejaculation. The characteristically wide bladder neck merges with a grossly dilated prostatic urethra, so the junction is nearly imperceptible both radiographically and by gross inspection. The prostatic urethra does, however, taper to a relatively narrow membranous urethra at the urogenital diaphragm. Retrograde ejaculation is common.

Chapter review

1.The three major findings in prune-belly syndrome are (1) deficiency of abdominal musculature, (2) bilateral intra-abdominal testes, and (3) anomalous urinary tract usually composed of varying degrees of hydronephrosis, renal dysplasia, tortuous ureters, enlarged bladder, and dilated prostatic urethra.

2.The single most important determinant of renal function is the degree of renal dysplasia.

3.The majority (95%) of those with prune-belly syndrome are males.

4.The ureters lack smooth muscle cells and have an increased amount of fibrous connective tissue; the most normal portion of the ureter with the greatest amount of smooth muscle is in the proximal segment. This is the segment that should be preserved for reconstruction.

5.The bladder is usually massively dilated.

6.The vas and seminal vesicles are often atretic.

7.The fusiform type of megalourethra involves deficiencies of the corpus cavernosum and corpus spongiosum, whereas the scaphoid variety involves a deficiency of corpus spongiosum only.

8.The deficiency in the abdominal wall musculature is usually medial and inferior.

9.The disease is generally classified into three categories according to severity: category I, patients with marked oligohydramnios with renal dysplasia and pulmonary hypoplasia; category II, moderate renal insufficiency; and category III, mild manifestations in which renal function is well maintained.

10.Infection and progressive renal insufficiency are the greatest threat to long-term survival.

11.Abdominal wall reconstruction has been demonstrated to improve bladder emptying and result in a more effective cough and improved defecation.

12.Circumcision in the neonatal period is advisable if there is no structural deformity of the penis.

13.Upper track reconstruction is clearly indicated in patients with evidence of decreasing renal function in the presence of hydronephrosis, recurrent urinary tract infections, and progression of the hydronephrosis.

14.Patients with pseudo-prune-belly syndrome with a normal or relatively normal abdominal wall exhibit many or all of the internal urologic features of prune-belly syndrome. These features may include dysplastic or dysmorphic kidneys or dilated and tortuous ureters.

15.In the neonate and in patients up to at least 6 months of age, transabdominal complete mobilization of the spermatic cord almost always allows the testis to be positioned in the dependent portion of the scrotum without dividing the vascular portion of the spermatic cord.