A subset of female patients with severe constipation report overlapping uro-gynecological symptoms which have been attributed to visceral hypersensitivity. To study colon morphology and motor function in female patients with medically refractory chronic constipation with or without uro-gynecological symptoms and to assess clinical outcomes following laparoscopic ileo-proctostomy. Colon anatomy and cecal emptying time were assessed with plain films and fluoroscopy following a standardized test meal mixed with barium. Transit time was determined with radiopaque markers. IBS-QOL and urinary incontinence questionnaires were employed to assess post-colectomy clinical response. In 21 consecutive patients, mean colon transit time (h) was 211.1 +/- 11.3, which was significantly greater than 58.9 +/- 5.1 of 10 normal subjects (P < 0.001). Mega-cecum was found in 15 (Group 1) with mean cecal volume of 587 +/- 27.9 cm(3), significantly greater (P < 0.001) than 169.5 +/- 10.4 cm(3) of six without mega-cecum (Group 2). Mean cecal empting time (days) of barium-mixed feces in Group 1, 4.0 +/- 0.6 was significantly greater than 1.33 +/- 0.21 in Group 2 (P < 0.001). Eighteen patients (Groups 1 and 2) who had laparoscopic ileo-proctostomy experienced significantly improved quality of life (P < 0.001). In particular, Group 1 patients benefited significantly from improved uro-gynecological symptoms. Hitherto an unrecognized mega-cecum with markedly impaired emptying function was found in patients with severe slow transit constipation and uro-gynecological symptoms. Subtotal colectomy relieved constipation and improved significantly uro-gynecological symptoms, suggesting strongly that mega-cecum is causally related to these symptoms.