Prune Belly Syndrome

What is Prune Belly Syndrome?

Prune Belly Syndrome (PBS) is a disorder of the urinary tract that may have life-threatening consequences in some cases.

It is a rare urinary disorder which affects individuals at birth, and is characterized by three types of abnormalities:

Picture of Prune Belly Syndrome

Picture 1 – Prune Belly Syndrome

  • Wrinkling of the abdominal skin, due to dearth of abdominal muscles
  • An non-descended testis
  • Problems associated with the urinary tract.

PBS has been named so due to the wrinkled mass on the belly, that appears as dried prune. In adults and adolescents, this appearance might assume a ‘pot-belly’ like arrangement.

Prune Belly Syndrome ICD 9 Code

The ICD 9 code of this disease is 756.71.

Prune Belly Syndrome Synonyms

This disorder is known by several other names like:

  • Congenital absence of the Abdominal Muscles
  • Abdominal Muscle Deficiency Syndrome
  • Obrinsky Syndrome
  • Eagle-Barrett Syndrome
  • Fröhlich Syndrome
  • Triad Syndrome (due to the triad of symptoms it exhibits)

Prune Belly Syndrome Incidence

This genetic disorder is evident in 1 among 40,000 to 50,000 births, mostly in males. However, 4 to 5% of cases have been reported in females, who did not display involvement of the urinary tract. PBS seems to be relatively prevalent in Canada and Nigeria. Twin pregnancies have shown greater occurrence of PBS, although the reason is obscure.

Prune Belly Syndrome Causes

The exact cause of this syndrome is not yet known. However, the cause of its occurrence has been explained through certain theories. There is a possibility that PBS occurs in the developmental stages of the fetus in the womb of its mother.

In 1903, a theory proposed by Strumme explained that the cause of PBS might be obstruction in the urinary bladder in the uterus. The abdominal wall suffers secondary-pressure atrophy due to expansion of the urinary tract, which leads to complications and protrusion of the belly.

Recent theories have proposed that it is a result of mesodermal arrest which may occur within the 6th to 10th week of pregnancy. According to the theory of mesodermal arrest, the flowing of mesoderm in the middle of endoderm and ectoderm of the embryo may be the root cause of the following complications. However, that does not entirely justify the causes.

Another theory, known as the Yolk Sac Theory, tried to highlight the cause of certain features associated with it. Stephens proposed that the prune-like look of the belly can be attributed to the problem of development of abdominal wall due to abnormal retention of yolk sac.

In some cases, the disease has been found to be common in twins. This might be suggestive of genetic link.  However, this has not yet been clearly established with proper evidence.

Prune Belly Syndrome Symptoms

Know about some of the classic symptoms of this syndrome in babies.

  • The appearance of the abdomen might be wrinkled, which may look like several creases on the skin.
  • In males, testes is absent in the scrotum (Cryptorchidism).
  • Intestinal outline can be seen from the outside including the movement of food within them.
  • Increased pulmonary secretions due to flawed cough mechanism as a result of absent abdominal muscles.
  • Constipation, caused due to weakened abdominal muscles.
  • Slowed walking or sitting.
  • Sometimes, it causes problems while urinating due to issues related to the urinary tract
  • By touching the abdomen, urinary tract organs can be felt.

Prune Belly Syndrome Diagnosis

The diagnosis of this syndrome can be done by following these means:

Prenatal diagnosis

Using prenatal ultrasound, this syndrome can be detected by the 11th week of pregnancy. However, prenatal diagnosis might often fail to show the findings clearly.

Postnatal diagnosis

  • Radiology tests are conducted on the new born to help in diagnosis. X-Rays help in ruling out the chances of other ailments including pulmonary complications. Findings of chest X-ray comprise of hypoplastic lungs. X-rays of the abdomen show distended abdomen depicting hydronephrotic urinary tract.
  • Ultrasound and VCUG are two diagnostic tools for investigating urinary tract. USG of the bladder and kidneys can detect distension of the bladder, parenchyma and cortical cysts. A voiding cystourethrogram (VCUG) can be ordered to distinguish between stasis and obstruction if renal problems persist. During pregnancy, fetal ultrasound techniques can be applied but diagnosis might be difficult.
  • CT scan can also be used to find the presence of PBS. Test findings may show the lack of arrangement of muscles in the abdomen apart from dilated bladder/ureter and hydronephrosis.
  • Renal cortical scans can be done to find the extent to which kidney functions have been impaired.
  • Blood tests measuring serial serum creatinine are done to check if there is any kidney problem in the newborn.
  • Intravenous pyelogram is an imaging tool which uses contrast dye to view the urinary tract structures. The rate of urine passed and path of the flow can be determined by this technique.

Prune Belly Syndrome Differential Diagnosis

The differential diagnosis of the disease, during bladder dilation, includes distinguishing the symptoms of PBS from those of other conditions like:

  • Posterior urethral valve syndrome
  • Megacystis-microcolon-intestinal hypoperistalsis syndrome
  • Urachal cyst
  • Ascites
  • Enteric duplication cyst
  • Bladder extrophy
  • Ureteropelvic junction obstruction

There also exists a prune-belly like variant which is often mistaken to PBS. It represents defects of the abdominal wall but in the absence of urologic problems or anomalies. The rectus muscles are not associated with this disease but only the muscles of the abdominal wall. It causes weakness sideways in the stomach, which can be identified with CT scans. Differential diagnosis should aim at ruling out the presence of this variant.

Prune Belly Syndrome Treatment

The treatment of this disease is based on factors like the age, medical history, and health of an affected child as well as response to certain medications. Curative options may vary with the severity of symptoms experienced by the child.

  • During the first week of birth, when complete diagnosis is done, treatment is opted for safeguarding the kidneys. For preventing pyelonephritis, prophylactic antibiotics are administered. It can be followed with surgery to remove obstruction.
  • Vesicostomy can be done to remove the fluid by drilling a hole into the abdomen. This may help in preventing instances of UTIs.
  • In multiple stages, orchiopexy can be performed due to the risk associated with testicular malignancy. By this process, testicles can be restored to the scrotum. .
  • Abdominal wall can also be reconstructed along with the urinary tract to improve the functions as well as the skin appearance of the neonatal.

Prune Belly Syndrome Complications

Severe cases of PBS have been reported. Patients with urethral obstructions are considered to be suffering from severe PBS. Pulmonary hypoplasia can be caused due to oligohydramnios and renal dysplasia. They might die instantly after birth as a result of the complication. Renal dysplasia is often a result of long term blockage of the urinary tract of the fetus. A study based on 8 PBS patients showed, 5 of them succumbing to renal failure.

Image of Prune Belly Syndrome

Picture 2 – Prune Belly Syndrome Image

A number of problems other than urologic have been traced in the patients. Around 50 to 60% of these patients have shown orthopedic deformities like congenital hip dislocation, talipes deformities and clubbed feet. Similarly, gastrointestinal disorders have also been found in PBS afflicted children.

Prune Belly Syndrome Prognosis

PBS is quite a life-threatening disease with variable prognosis. Stillbirth and miscarriages are common due to obstruction in urinary tract. Infants who manage to survive may have recurrent infection of the urinary tract. A poor outcome can be predicted by investigating serum creatinine, if an increase is initially noted in its level. Renal failures can be the outcome in these cases. Fetal chemistry, showing excess osmolarity and urine sodium, also indicates poor prognosis. However, good prognosis has been observed in cases where amniotic fluid volume is found to be normal. Fertility has been found to be stable in surviving patients.

Prune Belly Syndrome Life Expectancy

In patients with mild urinary tract issues (devoid of obstruction), lifespan has been found to be more or less normal. The rate of mortality varies between 55 to 60% even in such patients. Several factors may be involved in determining the life of a child with PBS, as the pathogenesis is not well-comprehended.


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