Prune Belly Syndrome

Synonyms include Eagle-Barrett syndrome, Abdominal Muscle Deficiency Syndrome, Congenital Absence of the Abdominal Muscles, Obrinsky Syndrome

It is a congenital abnormality of unknown aetiology with 3 characteristic features:

• Deficient development of abdominal muscles that causes the skin of the abdomen to wrinkle like a prune
• Cryptorchism
• Abnormalities of the urinary tract, usually hydronephrosis and vesico-ureteric reflux

There may also be pulmonary hypoplasia.

It is rare. A frequency of about 1 in 30,000 live births is found.¹ About 97% are boys.

OMIM discusses the possibility of genetic inheritance. If it were an X-linked recessive, it would be expected to occur in multiple brothers. The precise form of inheritance is unknown. It may be variable and it may often represent a new mutation. A sex linked autosomal recessive form of inheritance has been strongly suggested.²

A study from Cameroon³ found that most mothers were under 30 with singleton pregnancy but about two-thirds were complicated by placenta praevia, genital infections, pre-eclampsia, and anaemia from hookworm infestations.

Consistent features are:

• During pregnancy there is oligohydramnios.
• The newborn infant has a wrinkled abdomen that looks like a prune. This is because the abdomen swelled with fluid in utero, then lost that fluid after birth, leading to wrinkles of excess skin. The appearance is accentuated by poor abdominal musculature.
• Cryptorchism
• Dilated renal collecting structures
• Dilated bladder

More variable findings are:

• Underdeveloped lungs
• Cardiac anomalies
• Gastrointestinal anomalies
• Musculoskeletal abnormalities like club foot or abnormal limbs

The following tests are useful:

• Ultrasound
• Plain X-ray
• Intravenous pyelogram (IVP)
• Blood tests, especially renal function. A rise in blood urea suggests obstruction of the renal tract.

Other features³ include clubfoot (45%), pulmonary hypoplasia (27%), Potter facies (27%), imperforate anus (27%), and arthrogryposis (18%). In about 75% there are malformations⁴ of the cardiopulmonary, gastrointestinal, and orthopaedic systems.

Non-Drug

Parents will need much support and information.

Drugs

Antibiotics to treat or prevent UTI.

Surgical

Surgical repair can be quite complex. Renal transplantation may be required. Results seem satisfactory⁵ but the deficient abdominal wall needs repair or it causes breathing difficulties.

There is little controversy about orchidopexy but other surgery is more contentious. Some people advocate a conservative approach. Others do more radical surgery at about 10 days old. There is considerable variation in the nature of abnormalities and it is advised that the clinical condition should be as much a guide as radiological abnormalities. There can be a variety of renal, ureteric and urethral abnormalities.

Reconstruction of the abdominal wall is not just cosmetic but improves lung function.

Complications depend on the associated abnormalities. The most common is chronic renal failure that occurs in 25 to 30% of cases.

Prune Belly Syndrome is a serious and often life threatening problem. Miscarriage, stillbirth and neonatal death are common. Multiple concomitant anomalies and bilateral renal lesions are the cause of fetal or infant death in 75% of cases. Many infants are either stillborn or die within the first few weeks of life from severe lung or kidney problems, or a combination of congenital anomalies.

Many die in the first two years of life. Bilateral abnormal kidneys on ultrasound or renal scan, a peak serum creatinine above 0.7 mg./dl. and pyelonephritis are prognostic for renal failure.⁶

Of those who survive, successful fertility has been reported⁷ but this is usually due to modern fertility interventions.

There is no known prevention but the routine use of screening for fetal anomalies has resulted in rather more affected pregnancies being terminated.⁸ If an antenatal diagnosis of urinary obstruction is made it may be possible to perform intrauterine surgery⁹ to prevent the development of Prune Belly syndrome. The results seem promising.¹⁰

The condition was first described by Frolich in 1839. The description of prune belly is sometimes wrongly attributed to William Osler in 1901. He did not use the term. A variety of names are used eponymously with the syndrome including Frolich's syndrome, Eagle-Barrett syndrome, Obrinsky's syndrome and Frolich-Obrinsky syndrome.