Diagnosis of Hirschsprung Disease and Allied Disorders

Abstract

Radiology has an important role to play in the diagnosis of Hirschsprung disease (HSCR). Newborn babies typically present with abdominal distension, delayed passage of meconium and intolerance of food. A supine x-ray and lateral decubitus x-ray using a horizontal beam will show the extent of bowel distension and the presence or absence of fluid levels. If very few bowel loops are dilated, then the level of obstruction is likely to be fairly proximal, for example, jejunal atresia. If multiple loops are dilated but there are no significant air fluid levels, meconium ileus is the most likely diagnosis. When multiple bowel loops are dilated, and show fluid levels it can be difficult to differentiate between ileal atresia and Hirschsprung disease. In this case, a prone, horizontal beam x-ray with the buttocks elevated may be useful. In Hirschsprung disease with a rectosigmoid transition zone, this will usually show gas in a distended distal colon and a relatively narrow rectum, i.e. rectosigmoid index less than one.

When the diagnosis remains equivocal on plain x-rays, a contrast enema is very useful. In Hirschsprung disease, with a rectosigmoid transition zone, a lateral view of the abnormal rectum will show reduction in calibre compared to the non-involved descending colon. Less commonly, the transition zone will be visible at the splenic flexure. Total colonic aganglionosis is difficult to diagnose radiologically but is a much rarer condition. Other features of Hirschsprung disease include delayed evacuation of contrast on a 24-hour x-ray. Abnormal irregular sawtooth contractions can also be observed on fluoroscopy but less frequently in neonates than in infants.