A 56-year-old woman with moderate congenital mental retardation, dyslipidaemia and hypothyroidism came for consultation due to progressive constipation, increased abdominal perimeter and weight loss of 8 kg in the last 4 months. Physical examination revealed palpation of a central, hard, poorly demarcated hypogastric mass measuring approximately 10 x 8 cm. Laboratory tests, including acute phase reactants and digestive and gynaecological tumour markers, as well as gynaecological ultrasound, were normal. An abdominopelvic CT scan was performed, showing a giant dilatation of the rectum and left colon, occupied in the entire lumen by compacted faecal debris, causing displacement of all the abdominal organs and bilateral hydronephrosis without associated renal insufficiency. Colonoscopy up to the cecum with biopsies and pelvic MRI were normal. Anorectal manometry was performed, which showed preservation of the inhibitory rectoanal reflex. Treatment was started with oral polyethylene glycol and lactulose enemas, with notable clinical improvement, and she is currently on maintenance therapy with oral lactulose at high doses with weight gain and a bowel movement every 24-48 hours.

