The above image is of a baby suffering from Prune belly or Eagle-Barrett syndrome (PBS), which is a congenital defect with a rare incidence of 1 in 40,000 live births. It has a male predisposition. Prune belly syndrome is best characterized by a triad of clinical features:
● Abdominal muscle deficiency, exhibiting as the wrinkled abdominal skin
● Severe urinary tract abnormalities
● Bilateral cryptorchidism in males (undescended testicles)
Although PBS is defined by the clinical triad, its features are not limited to the triad. It may have variable effects on the cardiac, pulmonary, gastrointestinal, and musculoskeletal systems, making it a multisystem disorder.
Why is it called ‘Prune belly’ syndrome?
The picture of the baby’s abdomen is the answer to this question!
It is named after the wrinkled abdominal skin in the neonates which is due to the abnormality of the abdominal musculature. Beyond childhood, the abdomen acquires a smooth potbelly appearance, owing to the lack of abdominal muscles.
PBS is both sporadic and familial. The former is more common. PBS has some associations with chromosomal anomalies, particularly with trisomy 21.
The exact mechanism behind this syndrome remains unknown. Theories and observations suggest a role of urological obstruction in the baby during prenatal life which leads to a high-pressure system, dislocating the ureters and affecting the kidneys (renal dysplasia may be seen). The overdistended bladder may hamper the descent of the testis and the developmental process of the abdominal wall muscles.
The symptoms and
outcome of the PBS depend upon the severity of the urological anomalies. If the
urinary obstruction is severe, oligohydramnios ensues, which may lead to potter
sequence i.e. pulmonary hypoplasia,
dysmorphic facies, limb hypoplasia, etc.
The severity determines the effects on the kidneys, consequently, it can lead to intrauterine death or stillbirth. Some
babies may survive enough to see the light of the world, only to eventually succumb
to death a few months after birth. For the surviving babies, the clinical features
may immensely vary according to the graveness of the disease. Other than the triad,
the patient may
- – have a bulge in the lower abdomen due to distended bladder.
- – have poor cough mechanism
- – have constipation
- – have visible impressions of intestines through the skin of the belly as the abdominal muscles are absent.
- – have empty scrotum (no testes in baby boys).
- – have difficulty sitting upright or walking.
- – have a higher chance of urinary tract infections (UTIs).
- – have other congenital malformations.
PBS is usually a pre-natal diagnosis, visible around 12 weeks of gestation. Sometimes the features may remain obscured till the later quarter of the pregnancy.
After birth, the baby should undergo renal and bladder ultrasound, Contrast voiding cystourethrography (VCUG) to detect the presence and grade of the vesicoureteral reflux. Other tests include an intravenous pyelogram (IVP), renal scans and blood tests. Tests to scan other systems for potential involvement may be necessary.
Management is largely dependent upon the severity, acuteness, and defects that are present. Supportive treatment, antibiotics, surgical repair of the urinary tract abnormalities, closure of the abdominal wall, and correction of cryptorchidism are the management goals that are achieved by a multidisciplinary team in gradual steps.
Food for thought:
If one sibling has PBS, does it increase the chances in other siblings?
PBS is genetic. If one child has PBS, the chances are higher than normal in the siblings of the affected child.
References
Israel Franco, M. F. (2020, January 17). Prune Belly Syndrome. Retrieved from Medscape: https://emedicine.medscape.com/article/447619-overview
Manfred Wallner, M. K. (2019, October 30). Prune-belly syndrome. Retrieved from UpToDate: https://www.uptodate.com/contents/prune-belly-syndrome?search=prune%20belly%20syndrome&source=search_result&selectedTitle=1~19&usage_type=default&display_rank=1
professional07/08/2016., C. C. (2016, 08 07). Prune Belly Syndrome. Retrieved from Cleveland Clinic: https://my.clevelandclinic.org/health/diseases/16231-prune-belly-syndrome
Tagore, K. R., Ramineni, A. K., Vijaya Lakshmi, A. R., & N, B. (2011). Prune belly syndrome. Case reports in pediatrics, 2011, 121736. https://doi.org/10.1155/2011/121736
Seidel NE, Arlen AM, Smith EA, Kirsch AJ. Clinical manifestations and management of prune-belly syndrome in a large contemporary pediatric population. Urology. 2015 Jan. 85 (1):211-5.
Prune Belly Syndrome. National Organization for Rare Disorders. Available at https://rarediseases.org/rare-diseases/prune-belly-syndrome/. Accessed: January 10, 2017.
