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Findings: Dilated small and large bowel with associated air-fluid levels. Distended sigmoid colon with retained fecal material. Findings compatible with distal colonic obstruction.Barium enema - Segmental narrowing of the rectosigmoid with mild irregular contractions.

Diagnosis::Hirschsprung's Disease (congenital aganglionic megacolon).

Discussion: Congenital aganglionic megacolon is the most common cause of lower intestinal obstruction in the neonate. Abnormal innervation of the bowel is present with absence of Meissner's and Auerbach's plexuses and hypertrophied parasympathetic ganglia. The abnormality affects the colon to variable distances proximally from the anus and internal sphincter. Hirschsprung's disease has a 3.8 to 1 male predominance and is not classically associated with other congenital anomalies.

Affected neonates commonly present with signs of distal colonic obstruction including abdominal distention and infrequent or absent bowel movements. Early diagnosis is essential for reducing the significantly increased morbidity and mortality associated with enterocolitis(1).

Diagnosis is confirmed histologically with either a submucosal or a full thickness rectal biopsy in association with either anorectal manometry or barium enema. Radiographically, visualization of a rectosigmoid transition zone is a highly accurate indicator of disease(2). Irregular contractions of the involved segment is a very reliable sign as well. The combination of the transition zone and barium retention with a mixed pattern of stool after 24 hours has the highest predictive value(2).

Definitive treatment consists of surgical relief of the functional obstruction. Surgical procedures of choice include the endorectal pull-through, rectosigmoidectomy, retrorectal transanal pull-through, and anorectal myomectomy(1). A temporary colostomy may be performed to allow patient growth, and surgical intervention may be deferred altogether in the presence of enterocolitis(1).

References:
1. Kleinhaus S and Boley SJ. Hirschsprung's Disease.
In Robert Wiley editor: Pediatric Gastroenterology., pp. 698-705.

2. Rosenfield NS, Ablow RC, Markowitz RI, et al. Hirschsprung Disease:
Accuracy of the Barium Enema Examination. Radiology. 1984; 150 (2):393-400.

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