If pencil thin stools are caused from an obstruction, why wouldn't a c t scan show this. the e r dr told me it would show any obstructions. confused.

Constipation : You probably suffer from constipation, rather than obstruction. Indeed, an abdominal ct scan with oral contrast would show the bowel obstruction.

Ct scan: May see a mass if large enough or if contrast present. If still symptomatic you need a colonoscopy and or a barium enema. These tests see a colon lesion better often than ct. See a gastroenterologist or general surgeon. Radiologyinfo.Org has more info on barium enema and ct scan of abdomen and pelvis.