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Definition

Prune-belly syndrome is a rare congenital disorder, more common in males (approximately 95% are males), consisting of deficiency of abdominal wall muscles (absent or hypoplastic), cryptorchidism, and genitourinary malformations.

Alternate Names

Eagle-Barrett Syndrome; Triad Syndrome; Urethral Obstruction Malformation Sequence.

Symptoms

  • A partial or complete lack of abdominal muscles. There may be wrinkly folds of skin covering the abdomen.
  • Undescended testicles in males
  • Urinary tract abnormality such as unusually large ureters, distended bladder, accumulation and backflow of urine from the bladder to the ureters and the kidneys. Prune belly syndrome is characterized by elongated, dilated, and tortuous megaureters, which affect 81% of patients. Vesicoureteral reflux is common in these patients
  • Frequent urinary tract infections due to the inability to properly expel urine.

Diagnosis

Prune belly syndrome can be diagnosed via ultrasound while a child is still in-utero and should be suspected in fetuses with very large abdominal masses. An abnormally large abdominal mass is the key indicator, as the abdomen swells with the pressure of accumulated urine. In young children, frequent urinary tract infections often herald prune belly syndrome, as they are normally uncommon. If a problem is suspected, doctors can perform blood tests to check kidney function. Another test that may reveal the syndrome is the voiding cystourethrogram.

Etiology

Many theories have been proposed to explain the pathogenesis of this anomaly. The first one proposes that occurs an abnormal mesodermal development. The developmental arrest of the mesodermal elements would lead to severe abdominal laxity and defective development of the urinary tract. The second one is the urethral obstruction malformation complex. It proposes that pressure atrophy of the abdominal wall muscles occurs when urethral obstruction leads to massive distention of the bladder and ureters. Bladder distention would also interfere with descent of the testes and thus be responsible for the bilateral cryptorchidism. The mechanism responsible for the urinary tract dilatation and distention is a flap valve mechanism that results from a hypoplasia of the stromal and epithelial elements of the prostatic urethral. The hypoplasia of these elements leads to an underlying weakness and subsequent sacculation of the prostatic urethra. The last theory is the genetic defect that is suspected because of the predominance in males and few familial cases.

Complications

Prune belly syndrome can result in the distending and enlarging of internal organs such as the bladder and intestines. Surgery is often required to return these organs to their natural sizes.

Complications associated with Prune-Belly syndrome may include underdevelopment of the lungs (pulmonary hypoplasia), poor cough with respiratory infections as respiration requires use of accessory muscles(intubate and assist or control ventilation as needed). A lack of abdominal muscles leads to a poor cough mechanism, which, in turn, leads to increased pulmonary secretions. Pneumonia is a

Musculoskeletal abnormalities (clubfoot, dislocated hip, missing limb or digit, or pectus excavatum) are present in about 20% of cases, while cardiovascular abnormalities are seen in about 10% of cases.

Abnormal fixation of the gastrointestinal tract and failure to rotate during fetal development (malrotation) have also been described in the medical literature.

Treatment

PreNatal - Sonographic monitoring of the urinary tract and amniotic fluid volume is required throughout the pregnancy. When early and/or severe distention of the urinary tract is observed, a vesicoamniotic shunts with vesical decompression and correction of the amniotic fluid levels has been proposed to improve renal and pulmonary function. Anatomic abnormalities that warrant consideration of correction are those that interfere with critical fetal organ development. Experimental evidence suggests that fetal urinary tract obstruction, whether intermittent or persistent, can lead to renal dysplasia, which is often irreversible, even if the obstruction is relieved immediately after birth. The percutaneous placement of an indwelling catheter for urinary diversion is one possible therapy. Urinary tract decompression in the early second trimester is desirable to reduce the potential for ongoing damage to the developing kidneys. The benefits of such therapy remain controversial and are yet to be evaluated in a prospective, randomized fashion. As such, urinary diversion should be considered on a case-by-case basis. Additionally, correction of severe oligohydramnios as early as possible should reduce the possibility of pulmonary hypoplasia.

PostNatal - The type of treatment, like that of most disorders, depends on the severity of the symptoms. One option is to perform a vesicostomy, which allows the bladder to drain through a small hole in the abdomen. Boys may have an orchiopexy, which moves the testicles to their proper place in the scrotum. Abdominal wall reconstruction for both aesthetics and function is often necessary. Because 75% of individuals with Prune-Belly syndrome have extra urinary anomalies, a thorough evaluation, especially cardiac, should be performed.

Prognosis

The prognosis depends on the degree of renal function compromise. Outcome is typically good in cases of Prune-Belly Syndrome with normal amniotic fluid volume. The early urinary obstruction, present in the majority of cases, leads to renal failure, pulmonary hypoplasia, and death in the neonatal period. More than 60% of infants died in the first week of life. Early decompression of severe bladder obstruction improves the prognosis. Fetuses that develop mild urinary tract distention have better prognosis. Mild hydronephrosis and megalourethra may be the only manifestations in these cases.

Recurrence risk

Unknown, but low. A familial occurrence has been seen in some affected patients, suggestive of an X-linked inheritance 6. A multifactorial, or polygenic, inheritance has also been proposed.

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