PURPOSE:The aim of the present study was to evaluate how distention of the rectum with contrast medium at defecoperitoneography affected pelvic anatomy,i.e.,position, form, and size, of organs and pouch of Douglas.PATIENTS AND METHODS:Twenty‐six female patients with a peritoneocele at defecoperitoneography were selected for the present study. Radiographs taken at the start, before, and after filling the rectum with contrast medium were compared.RESULTS:There was an obvious change in the position of the organs in the pelvis when the rectum was distended with contrast medium. The peritoneocele disappeared completely in 19 of the patients and was reduced in size in the remaining 7 patients, and the enterocele disappeared completely in 13 patients. The small bowel and vaginal portion of the uterus moved cranially.CONCLUSIONS:A distended rectum may conceal existing pathology, such as peritoneocele and enterocele, at defecoperitoneography. Defecoperitoneography should, therefore, include a radiograph before the rectum is filled. This radiograph shows the habitual anatomy of the patient in the sitting position and may demonstrate pathologic findings.