Prune belly syndrome

Synonyms: include Frölich's syndrome, Obrinsky-Frölich syndrome, Eagle-Barrett syndrome, abdominal muscle deficiency syndrome, congenital absence of the abdominal muscles, Obrinsky's syndrome

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

• Deficient development of the abdominal muscles, which 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.

Epidemiology

It is rare with a frequency of about 1 in 30,000 live births.¹² About 97% are boys.

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.³

A study from Cameroon found that most mothers were aged under 30 with singleton pregnancy but about two-thirds were complicated by placenta praevia, genital infections, pre-eclampsia, and anaemia from hookworm infestations.⁴

Presentation

Consistent features are:

• Pregnancy is complicated by 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 and dilated bladder.

More variable findings are:

• Underdeveloped lungs.

• Cardiac anomalies.

• Gastrointestinal anomalies.

• Musculoskeletal abnormalities like talipes (clubfoot) or abnormal limbs.

Investigations

The following tests are useful:

• Ultrasound.

• Plain X-ray.

• Intravenous pyelogram (IVP).

• Blood tests, especially renal function (rise in blood urea suggests obstruction of the renal tract).

Associated diseases

Other features (in order of likelihood) include:

• Malformations of the cardiopulmonary, gastrointestinal, and orthopaedic systems.⁵

• Clubfoot.

• Pulmonary hypoplasia.

• Potter facies.

• Imperforate anus.

• Arthrogryposis.⁴

Management

General measures

Parents will need support and information.

Pharmacological

Antibiotics to treat or prevent urinary tract infection.

Surgical

Renal transplantation may be required. Surgical repair can be quite complex. Results seem satisfactory but the deficient abdominal wall needs repair or it causes breathing difficulties.⁶

There is little controversy about orchidopexy but other surgery is more contentious:

• Some 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.

Complications

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

Prognosis

Prune belly syndrome is a serious and often life-threatening problem. Miscarriage, stillbirth and neonatal death are common.

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. Bilateral abnormal kidneys on ultrasound or renal scan, a nadir serum creatinine above 62 μmol/L and pyelonephritis are prognostic for renal failure.⁷

Of those who survive, successful fertility has been reported but this is usually due to modern fertility interventions.⁸

Prevention

The routine use of screening for fetal anomalies has resulted in more affected pregnancies being terminated.⁹ If an antenatal diagnosis of urinary obstruction is made, it may be possible to perform intrauterine surgery to prevent the development of prune belly syndrome.¹⁰ The results seem promising.¹¹¹²