Idiopathic megarectum and megacolon.

A 56-year-old female with a prior medical history of congenital mental retardation, hypercholesterolemia, and hypothyroidism consulted for severe constipation refractory to laxatives, which required enemas for evacuation, associated with abdominal distension and weight loss –8 kg over the last six months–. Physical examination revealed a hard, long, rounded mass measuring 8 x 10 cm in the central hypogastrium. Laboratory parameters, including acute phase reactants and tumor markers, were within normal ranges, and a gynecological echogram was normal. An abdominal computerized tomography scan (Fig. 1, coronal reconstruction; Fig. 2, axial images) showed a giant dilation of the rectum and left bowel, occupied by multiple compacted feces, displacing the abdominal viscera and resulting in bilateral hydronephrosis without renal failure. A colonoscopy reaching the cecum, biopsies, and pelvic magnetic resonance imaging were all normal, while rectoanal manometry disclosed a proper relaxation of the internal anal sphincter in response to rectal distension. Treatment with oral polyethylene glycol electrolyte solution and rectal lactulose led to progressive clinical improvement, and the patient had a successful outcome on maintenance therapy with oral lactulose. PICTURES IN DIGESTIVE PATHOLOGY