Bruce J. Schlomer, MD
Laurence S. Baskin, MD, FACS, FAAP
BASICS
DESCRIPTION
• Prune belly refers to the classic appearance of abdominal wall wrinkling and budging flanks caused by varying degrees of abdominal wall deficiency, found almost exclusively in males (image) (1)
• Prune belly syndrome (PBS) triad:
– Deficient abdominal musculature
– Bilateral cryptorchidism
– Urinary tract anomalies (eg, dilated prostatic urethra, renal dysplasia, hydroureteronephrosis)
• Incomplete variants lack abdominal wall features; females lack gonadal anomalies
• Woodard classification:
– Type I: Usually fatal; marked oligohydramnios due to severe renal dysplasia or bladder outlet obstruction with pulmonary hypoplasia and skelet al anomalies (Potter sequence)
– Type II: Full spectrum of disease with no immediate threat to life; renal dysplasia; hydroureteronephrosis; possible mild pulmonary hypoplasia
– Type III: Mild external features of triad or incomplete variant; no evidence of pulmonary hypoplasia, mild uropathy
• Synonyms: Eagle–Barrett or Triad syndrome
EPIDEMIOLOGY
Incidence
• 3.8/100,000 live births
• 95% males
• Higher incidence in African Americans
• Lower incidence in Hispanic population
• Increased incidence in younger mothers
Prevalence
N/A
RISK FACTORS
Slightly increased risk in African Americans and younger mothers
Genetics
• Most cases are sporadic, with normal karyotype.
• Potential inheritance patterns in rare familial cases (influenced autosomal recessive; X-linked)
• Monozygotic twins reported concordant and discordant for PBR suggests some nongenetic basis
PATHOPHYSIOLOGY
• Exact mechanism unknown:
– Early in utero transient urethral obstruction
– Mesodermal developmental defect
• Abdominal defects due to deficient musculature medially and inferiorly:
May be partial hypoplasia of the abdominal wall to complete absence of musculature
• Testes:
– Usually intra-abdominal (over iliac vessels)
– Epididymis poorly attached
– Descent in part affected by mechanical forces (eg, large bladder, low intra-abdominal pressures)
• Kidneys:
– Dysplasia in 50%, to varying degrees
– Nonobstructive hydronephrosis is common; does not correlate to degree of dysplasia
• Ureters:
– Dilated, tortuous, and redundant; distal >proximal
– Increased ratio of collagen to smooth muscle
– Poor peristalsis and ureteral coaptation lead to stasis and reflux
– ∼75% with reflux
• Bladder:
– Enlarged with no significant hypertrophy
– May have urachal pseudodiverticulum
– Urachus patent in up to 30%
– Increased ratio of collagen to smooth muscle
– Urodynamics commonly show normal compliance, delayed sensation, large capacity; 50% void with normal pressures and flow, and have low postvoid residual
• Prostatic urethra:
– Dilated due to prostatic hypoplasia
– 20% can have distal obstructive lesions (eg, valves, atresia, stenosis)
• Anterior urethra:
– Usually normal
– Most common abnormalities: Megalourethra and urethral atresia (latter can be fatal unless patent urachus)
– Megalourethra can be caused by transient obstruction
– Fusiform: Defect in corpus cavernosum and spongiosum; entire phallus dilates on voiding
– Scaphoid: Defect in corpus spongiosum; only ventral urethra dilates
• Fertility:
– Usually infertile (rare cases of paternity with sperm retrieval) due to azoospermia
– Histologic defect in testes
– Atretic vas deferens and seminal vesicles
– Retrograde ejaculation from incompetent bladder neck
ASSOCIATED CONDITIONS
• Genetic:
– Turner syndrome; trisomy 13, 18, and 21; Beckwith–Wiedemann syndrome
• Gastrointestinal:
– Malrotation of gut (∼40%); bowel atresia, gastroschisis, omphalocele, imperforate anus (rare)
• Pulmonary:
– >50% with pulmonary hypoplasia
• Cardiac:
– Atrial and ventricular septal defects, tetralogy of Fallot, valvular anomalies, patent ductus arteriosus
• Musculoskelet al:
– Scoliosis; vertebral anomalies, congenital hip dislocation, club feet
GENERAL PREVENTION
None known
DIAGNOSIS
HISTORY
• Gestational history (eg, oligohydramnios, prenatal hydronephrosis)
• Rarely positive family history
PHYSICAL EXAM
• 75% will have nonurologic manifestations
• General: Observe for Potter facies (eg, wide set eyes, flattened nasal bridge)
• Heart: Auscultate for murmurs due to atrial or ventricular septal defects, patent ductus arteriosus
• Lungs/chest: Auscultate for pneumothorax; evaluate for pectus excavatum/carinatum
• GI: Associated with gastroschisis or omphalocele; imperforate anus; intestinal malrotation, atresia, or stenosis
• Urologic: Evaluate meatus, observe urinary stream, attempt to palpate testes
• Abdomen: Wrinkled, redundant skin over lower abdomen with bulging flanks
• Extremities: Observe for dimpling on lateral aspect of knees, knock knees, clubfoot, hip dislocation, scoliosis
DIAGNOSTIC TESTS & INTERPRETATION
Lab
• Serum electrolytes, urea nitrogen, and creatinine:
• Nadir creatinine <0.7 ng/dL is predictive of adequate renal function through childhood.
• Urinalysis and urine culture as indicated
Imaging
• Prenatal US: Bilateral hydroureteronephrosis, thin-walled distended bladder, possible oligohydramnios
• Chest x-ray (pneumothorax)
• Postnatal renal/bladder US (degree of renal dysplasia and hydroureteronephrosis)
• Radioisotope studies (technetium-99m/99Tc):
– DMSA at 4–6 wk to assess renal parenchymal function
– MAG3 scan to assess presence/degree of obstruction
Diagnostic Procedures/Surgery
• VCUG:
– Perform while on antibiotic prophylaxis
– Reflux in up to 75% of cases
– Large bladder and dilated prostatic urethra tapering to membranous urethra
Pathologic Findings
• Renal dysplasia on biopsy
• Ureter and bladder with increased collagen and fibrous tissue
DIFFERENTIAL DIAGNOSIS
• Megacystis microcolon
• Intestinal hypoperistalsis syndrome (marked female predominance
• Posterior urethral valves (prenatal appearance can be similar)
TREATMENT
GENERAL MEASURES
• Primary goal is to preserve renal function and prevent UTI
• Early aggressive surgery for dilated urinary tract without evidence of progressive renal dysfunction or UTIs should be avoided
– High complication rate
• Demonstrate proper bladder emptying
– Double voiding
– Timed voiding
– Clean intermittent catheterization (CIC)
• UTI prophylaxis
• Avoid instrumentation early to reduce UTI risk
MEDICATION
First Line
• UTI prophylaxis:
– Ampicillin 25 mg/kg/d as neonates
– Trimethoprim–sulfamethoxazole 2 mg/kg once daily or nitrofurantoin 1–2 mg/kg once daily beyond 2 mo of age
Second Line
None
SURGERY/OTHER PROCEDURES
• Prenatal: Vesicoamniotic shunting for oligohydramnios in 2nd trimester (controversial)
• Consider circumcision to reduce incidence of UTI
• Urinary tract reconstruction (eg, reimplant) is controversial due to potential for improvement or resolution, stabilization of function, and high complication rates (2)
• Early intervention may be warranted with progressive/severe hydronephrosis, progressive renal failure, or recurrent UTIs (2)
– Temporary cutaneous vesicostomy or bilateral cutaneous pyelostomies (avoid proximal ureterostomies)
– Ureteral reimplantation with/without tapering
• Reduction cystoplasty reserved for large urachal diverticulum or as part of extensive reconstruction, since large bladder tends to recur
• Orchidopexy:
– Transabdominal, preferably done by 1 yr of age or in combination with other procedures:
• Abdominal wall reconstruction for cosmesis, may enhance Valsalva voiding and improve bladder emptying (3)
• Renal transplantation
– 1/3 will eventually need renal transplant
– Achieve adequate bladder emptying prior to transplant
ADDITIONAL TREATMENT
Radiation Therapy
N/A
Additional Therapies
N/A
Complementary & Alternative Therapies
Use of corsets for abdominal wall laxity have been reported
ONGOING CARE
PROGNOSIS
• Degree of renal dysplasia most important determinant of long-term survival
• Up to 1/3 develop renal failure and will require dialysis/renal transplantation
COMPLICATIONS
• Renal failure
• Respiratory failure (early)
• Recurrent UTIs
• Urosepsis
FOLLOW-UP
Patient Monitoring
• Serial evaluation of renal function, bladder function and emptying, and for UTIs
• Imaging is individualized
Patient Resources
• http://www.urology.ucsf.edu/patient-care/children/urinary-tract-obstruction/prune-belly-syndrome
• Prune belly syndrome network: www.prunebelly.org
REFERENCES
1. Hassett S, Smith GH, Holland AJ. Prune belly syndrome. Pediatr Surg Int. 2012;28:219–228.
2. Denes FT, Arap MA, Giron AM, et al. Comprehensive surgical treatment of prune belly syndrome: 17 years experience with 32 patients. Urology. 2004;64:789–793.
3. Lesavory MA, Chang EI, Suliman A, et al. Long-term follow-up of total abdominal wall reconstruction for prune belly syndrome. Plast Reconstr Surg. 2012;129:104e–109e.
ADDITIONAL READING
Baskin LS, Kogan BA. Handbook of Pediatric Urology, 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005.
See Also (Topic, Algorithm, Media)
• Polyhydramnios/Oligohydramnios
• Prune Belly (Eagle–Barrett or Triad) Syndrome Image 
• Undescended Testes (Cryptorchidism)
CODES
ICD9
• 257.2 Other testicular hypofunction
• 748.5 Agenesis, hypoplasia, and dysplasia of lung
• 756.71 Prune belly syndrome
ICD10
• E29.1 Testicular hypofunction
• Q33.6 Congenital hypoplasia and dysplasia of lung
• Q79.4 Prune belly syndrome
CLINICAL/SURGICAL PEARLS
• Antireflux surgery with high complication rates; avoid if possible.
• Prenatally can be difficult to distinguish from posterior urethral valves.
• Goal is to avoid renal damage, UTIs.