Eagle Barrett Syndrome (Also Known as Prune-Belly Syndrome [PBS]) in an Adult

Christopher Wen, MD; Dorothy J. Marquez, MD; Allen J. Cohen, PhD, MD

Disclosures

Appl Radiol. 2004;33(4) 

In This Article

Discussion

Prune-belly syndrome is a congenital disorder characterized by the clinical triad of cryptorchidism, hypoplasia of the abdominal musculature, and abnormalities of the urinary tract. The term "prune belly" reblects the characteristic wrinkled appearance of the abdominal wall in the newborn due to the complete or partially complete absence of abdominal wall muscles. In adolescent and adult life, the abdomen often assumes a smooth "pot-belly" configuration. In the United States, the incidence of PBS is 1 in 35,000 to 50,000 live births; it occurs in all races. There are other associated anomalies, including clubfoot, intestinal malrotation, pulmonary dysplasia, congenital hip dislocation, and cardiac defects due to the sequela of oligohydraminos in utero.[1] Ninety-five percent of cases occur in males. Diagnosis is made in utero using ultrasound (US) or in the neonate with characteristic clinical findings. The diagnosis is suspected in the fetus when US imaging reveals an enlarged bladder, dilated ureters, and an abnormal abdominal wall. However, the same constellation of US findings can be caused by posterior urethral valves (PUV) with severe hydroureteronephrosis. Amniotic bluid volume may be normal or decreased in neonates with PBS. Occasionally, PBS can be seen in older children or adults with renal failure, recurrent infections, or hypertension.

Morbidity relates to the degree of dilation of the urinary tract, in which poor ureteral peristalsis and weak forward propulsion of urine in the ureters results in stasis, infection, and stone formation. Renal failure results from underlying renal dysplasia and the aforementioned complications of urinary stasis. Twenty percent of patients are stillborn, 30% die of renal failure or urosepsis within the first 2 years of life, and the remaining 50% have varying degrees of urinary pathology.

In the 1970s, half of the patients with PBS died in early infancy. Currently, the survival rate has improved markedly. The severe abdominal distention also is marked by pulmonary hypoplasia related to the patient's large abdominal contents and compromise of the thorax during fetal development.

Older theories postulated that lower urinary tract obstruction at the level of the prostate caused overdistension of the bladder. In turn, hydroureter and hydronephrosis developed. The mass effect from the dilated upper urinary tract interfered with descent of the testes and development of abdominal wall musculature.[1] Newer hypotheses ascribe the syndrome to a gestational insult disrupting mesodermal development. Embryogenesis of the abdominal wall musculature and lining of the genitourinary tract are consequently damaged.[1] The genetic basis of PBS is uncertain. An X-linked defect is suggested by the predominance of affected males. However, females can be affected, casting doubt upon this observation.

Hydronephrosis and varying degrees of renal dysplasia are present in >50% of cases. There may be clubbing of the calyces, narrowing of infundibula, and cyst formation. The ureters often exhibit gross dilation, elongation, and tortuosity due to replacement of smooth muscle with fibrous tissue. The distal ureter is more affected than the proximal ureter. Often, the bladder is enlarged and nontrabeculated because of the replacement of smooth muscle by collagen. It can be elongated and attached to a patent urachus or urachal diverticulum superiorly. The prostate is markedly hypoplastic, leading to dilation of the prostatic urethra. The anterior urethra is abnormal in 70% of cases, often in the form of a scaphoid megalourethra. Females can have urethral atresia. Virtually all males have bilateral undescended testes. Females usually have normal ovaries, but abnormalities of the uterus and vagina.

Historically, the diagnosis was made based on: 1) physical examination; 2) a chest radiograph showing hypoplastic lungs and distended blanks; and 3) IVU findings of dilated and clubbed renal calyces, markedly dilated and tortuous ureters, and a large vertical trabeculated bladder. Radiologic findings in PBS that distinguish it from PUV include greater dilation and redundancy of the distal thirds of the ureters and anterior urethral abnormalities.[2,3] In some rare cases, urethroscopy may be necessary to differentiate these entities. With the increasing use of noncontrast CT to evaluate the genitourinary system, awareness of the appearance of PBS on CT is important.

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