Pediatrics

Prune Belly Syndrome

OVERVIEW: What every practitioner needs to know

Prune Belly Syndrome (PBS) is characterized by abdominal wall muscular deficiency, intraabdominal testes, and an anomalous urinary tract. The most identifiable aspect is the characteristic abdominal appearance that gives this syndrome its name.

PBS is also referred to as the triad syndrome, Eagle-Barrett syndrome, and abdominal muscular deficiency syndrome. It may be identified on prenatal ultrasound due to the significant dilation of the entire urinary tract (kidneys, ureters, and bladder).

An incomplete form of the syndrome called "pseudoprune belly syndrome" has been described with a normal abdominal wall, descended testes, and the presence of urinary tract anomalies noted with PBS.

Pathogenesis

Two primary etiologies have been suggested for the development of PBS:

  1. Urinary outlet obstruction: Multiple anomalies of the distal urethra in boys with PBS have been described. Delayed canalization of the anterior and posterior segments of the urethra has been theorized to cause transient obstruction, leading to bladder distension and compression of the developing abdominal wall, hindering the migration of the ventral mesenchyme, resulting in abdominal wall abnormalities.

  2. Abdominal muscle defect: An alternative theory is that a primary defect of the intermediate and lateral mesoderm leads to abnormalities in the development of the abdominal wall. This impacts the embryogenesis of the mesonephric and paramesonephric ducts and therefore the development of the urinary tract.

Presentation

Prenatal - Ultrasonography has made it possible for PBS to be considered, although the diagnosis cannot be confirmed until after birth.

The presence of a dilated urinary tract - hydroureteronephrosis and megacystis - associated with the presence of a dilated urethra in a male fetus can suggest the diagnosis.

Postnatal - The typical abdominal wall findings allow immediate postnatal confirmation of the diagnosis (Figure 1 and Figure 2). Additionally, the presence of undescended testes and penile and urethral anomalies confirms the diagnosis. In females and in pseudoprune belly syndrome, the diagnosis can be missed at birth.

Figure 1.

Newborn with prune belly syndrome.

Figure 2.

Same infant - note lack of testis descent.

Non-urologic manifestations

Pulmonary disorders requiring mechanical ventilation have been reported in 58% of children with prune belly syndrome. Musculoskeletal anomalies have been noted in 23%-40% of cases. Pectus excavatum has been noted along with club feet, hip dislocations, torticollis, and metatarsus adductus.

What other disease/condition shares some of these symptoms?

Prenatal ultrasound findings may suggest posterior urethral valves. At birth, the diagnosis becomes evident on physical examination.

What caused this disease to develop at this time?

Most cases are sporadic. Although frequently noted in twin pregnancies, most twins are discordant for PBS.

What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?

Prenatal diagnosis is now possible. Antenatal ultrasonography indicates the presence of bilateral hydroureteronephrosis associated with an enlarged bladder, which is suggestive for the diagnosis. Amniotic fluid volume may be decreased or normal. In male fetuses, PBS needs to be differentiated from obstruction secondary to posterior urethral valves.

At birth, initial evaluation should include complete physical evaluation for associated congenital anomalies. The spectrum of anomalies is variable, so evaluation should be individualized.

Would imaging studies be helpful? If so, which ones?

Postnatal evaluation of renal anatomy with the use of ultrasound is the first step. Voiding cystourethrogram (VCUG) is indicated to identify the presence of vesicoureteral reflux and urethral obstruction. Diuretic renography is indicated to ensure lack of ureteral obstruction and to provide baseline evaluation of differential renal function.

Lack of bladder emptying is a common finding and can be identified on VCUG and post-void ultrasound.

Ongoing radiologic evaluation is critical for long-term management.

If you are able to confirm that the patient has prune belly syndrome, what treatment should be initiated?

Initial management should be directed to intensive care unit monitoring at birth and placement of a catheter for urinary drainage.

Institution of antibiotic prophylaxis should be considered. In boys, circumcision may be considered.

Management of the urinary tract:

  • Once medically stable, urinary tract evaluation should focus on upper tract preservation. If there is no evidence of urethral obstruction, close monitoring of the serum creatinine and radiographic follow-up of the upper tracts is appropriate. In the most lethal form of the syndrome associated with complete urethral obstruction, early urinary drainage is crucial. Urinary drainage and improvement of the abdominal wall appearance can be achieved with the use of abdominal wall binders or the use of abdominoplasty (see below).

  • In the context of rising creatinine, recurrent infection, or obstruction, surgical intervention becomes necessary. Initial management should be with cutaneous vesicostomy (Figure 3). This will allow complete drainage of the urinary tract and allow stabilizaton of the upper tracts and creatinine. Higher diversion with cutaneous ureterostomy or pyelostomy may be required in some children when vesicostomy does not provide adequate drainage. If high diversion is required, renal biopsy may be performed at the same time to determine the extent of renal dysplasia. Closure of the vesicostomy may be delayed until 2-3 years of age, when renal function has stabilized. When urinary drainage remains a continued concern, closure of the vesicostomy may be combined with the use of continent urinary diversion to assure continued bladder emptying.

  • Surgical reduction of the bladder and ureters has not been shown to be universally beneficial in improving urinary drainage.

Figure 3.

Vesicostomy for urinary tract management in an infant with PBS

Management of the abdominal wall:

  • Surgical plication of the abdominal wall has been performed to enhance the appearance of the abdomen (Figure 4). Multiple techniques have been developed to perform surgical plication. Most use a double vesting technique or resection of the thinned abdominal fascia. In addition to the cosmetic benefits associated with abdominal wall plication (Figure 5), voiding efficiency has been noted to be improved as well based on reduction in residual volumes.

Figure 4.

"Pot-bellied" appearance of older boy with PBS

Figure 5.

Completed abdominal wall reconstruction in a child that also has continent urinary diversion

Management of undescended testes:

  • Early orchiopexy should be considered. Open laparoscopic orchiopexy may be performed at the time of abdominoplasty to take advantage of the significant dissection so that the testes can be placed in the scrotum without division of the spermatic vessels (Fowler Stephens orchiopexy). Laparoscopic orchiopexy can be safely performed in boys with PBS with preservation of the spermatic vessels, and is currently the recommended modality.

What are the adverse effects associated with each treatment option?

Boys with PBS are universally infertile. Histologically abnormal testes have been noted in boys with PBS. However, causes for infertility are multifactorial. Hypoplasia of the prostate and the mesonephric duct structures may play an important role.

Despite good urinary drainage, urinary tract infections are noted in many children.

What are the possible outcomes of prune belly syndrome?

Early mortality has been noted to be as high as 29%. A large percentage of infants are born prematurely (43%), and many of the deaths occur in this group of children. Interestingly, renal failure is uncommon (4%) in infancy. A nadir creatinine greater than 0.7 mg/dl in the first year of life is strongly predictive of renal failure. Also, recurrent pyelonephritis predicts long-term renal injury.

Thirty percent of children will develop renal failure during childhood and adolescence. Renal transplantation offers the best potential for growth and development. Graft survival is similar to controls, but bladder deterioration should be evaluated closely.

The majority of boys that have had orchiopexy have normal scrotal testes and normal puberty with good sexual function. However, they are universally infertile. Use of advanced reproductive techniques (intracytoplasmic sperm injection - ICSI) have been associated with possibility of pregnancy.

What causes this disease and how frequent is it?

The incidence of PBS is 3.8/100,000 live births. Fifty percent of patients are Caucasian, 31% are African American, and 10% are Hispanic. Ninety-five percent of patients are male. Forty-three percent are premature. In-hospital mortality has been reported to be 29% due to complications of prematurity.

How do these pathogens/genes/exposures cause the disease?

Most cases are sporadic, although examples of familial PBS has been reported. Some investigators have suggested an autosomal recessive, sex-influenced mode of inheritance.

Other clinical manifestations that might help with diagnosis and management

N/A

What complications might you expect from the disease or treatment of the disease?

N/A

Are additional laboratory studies available; even some that are not widely available?

N/A

How can this be prevented?

N/A

What is the evidence?

References

Initial descriptions of the syndrome and it nomenclature.

Nunn, IN, Stephens, FD. "Triad syndrome: A composite anomaly of the abdominal wall, urinary system and testes". J Urol. vol. 86. 1961. pp. 782-94.

Eagle, JF, Barrett, GS. "Congenital deficiency of the abdominal musculature with associated genitourinary abnormalities: A syndrome: Report of 9 cases". Pediatrics. vol. 6. 1950. pp. 721-36.

Welch, KJ, Kearney, GP. "Abdominal musculature deficiency syndrome: Prune belly". J Urol. vol. 111. 1974. pp. 693-700.

Recent publications of the syndrome and outcomes.

Routh, JC, Huang, L, Retik, AB, Nelson, CB. "Contemporary epidemiology and characterization of newborn males with prune belly Syndrome". Urology. vol. 76. 2010. pp. 44-8.

Bellah, RD, States, LJ, Duckett, JW. "Pseudoprune-Belly Syndrome: Imaging findings and clinical outcome". AJR Am J Roentgenol. vol. 167. 1996. pp. 1389-93.

Noh, PH, Cooper, CS, Winkler, AC. "Prognostic factors for long-term renal function in boys with the prune-belly syndrome". J Urol. vol. 162. 1999. pp. 1399-401.

The ongoing debate regarding pathogenesis of prune belly syndrome

Burton, BK, Dillard, RG. "Brief clinical report: prune belly syndrome: observations supporting the hypothesis of abdominal overdistension". Am J Med Gen. vol. 17. 1984. pp. 669-72.

Stephens, FD, Gupta, D. "Pathogenesis of the prune belly syndrome". J Urol. vol. 152. 1994. pp. 2328-31.

Surgical management and outcomes in prune belly syndrome

Dénes, FT, Arap, MA, Giron, AM. "Comprehensive surgical treatment of prune belly syndrome: 17 years' experience with 32 patients". Urology. vol. 64. 2004. pp. 789-93.

Monfort, G, Guys, JM, Bocciardi, A. "A novel technique for reconstruction of the abdominal wall in the prune belly syndrome". J Urol. vol. 146. 1991. pp. 639-40.

Docimo, SG, Moore, RG, Kavoussi, LR. "Laparoscopic orchidopexy in the prune belly syndrome: a case report and review of the literature". Urology. vol. 45. 1995. pp. 679-81.

Kolettis, PN, Ross, JH, Kay, R, Thomas, AJ. "Sperm retrieval and intracytoplasmic sperm injection in patients with prune-belly syndrome". Fertil Steril. vol. 72. 1999. pp. 948-9.

Patil, KK, Duffy, PG, Woodhouse, CRJ, Ransley, PG. "Long-term outcome of Fowler-Stephens orchiopexy in boys with prune-belly syndrome". J Urol. vol. 171. 2004. pp. 1666-9.

Ongoing controversies regarding etiology, diagnosis, treatment

Two controversies remain in prune belly syndrome. The pathogenesis of the syndrome continues to be debated.

Additionally, the controversy surrounding management revolves around the role of surgery of the urinary tract in children with prune belly syndrome. Although some claim that extensive ureteral tailoring is required to improve drainage of the kidneys, the prevailing opinion remains that minimizing surgical intervention is preferable. Close follow-up with surgical reconstruction is appropriate only for patients that demonstrate renal deterioration.

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