[Radiologic investigation of external rectal prolapse. Assessment in 48 patients with defecography, seven of them also with dynamic CT of the pelvis]

PURPOSE: To report our personal experience in 48 patients with external rectal prolapse examined with defecography, evaluating radiological signs and the indications for surgical treatment. We also report the results of 7 patients with severe prolapse submitted to dynamic CT of pelvis. MATERIAL AND METHODS: The findings relative to 48 patients suffering from external prolapse, 27 women and 21 men, (mean age 58 years), were retrospectively reviewed. In our study protocol the patient is made to sit on a defecographic commode with the pelvis in lateral projection and radiographic images are acquired at rest, on contraction and on evacuation. Dynamic CT of pelvis with axial and coronal scans of the pelvic floor was carried out in 7 patients with severe prolapses. Twenty-six of 48 patients underwent rectopexy. RESULTS: The main symptoms were anorectal and perineal weight sensation (93%), perineal disturbance in the sitting position (91%) and anorectal pain extended to sacral area (83%). Manometry, which was performed in 36 cases, showed a rectoanal inhibitory reflex evokable at high volumes of air, especially in incontinent subjects. Defecography demonstrated external rectal prolapse in all cases; rectal intussusception in 32, mucosal prolapse in 30, abnormal widening of the anorectal angle in 24 (16 of them were incontinent), rectocele in 22 and perineal descent syndrome in 16 cases. DISCUSSION AND CONCLUSIONS: External rectal prolapse is sometimes a dynamic progression of a rectal intussusception. In anorectal intussusceptions, the invaginatum involves the anal canal, thus causing the external prolapse. Defecography clearly shows the continuation of invagination out of the anus, with the formation of prolapse. Dynamic CT proved accurate in detecting the rectum morphology, but added no further information to defecography, except for the diastasis of anosphincterial muscles. Therefore, we conclude that defecography is the method of choice, though complementary to other instrumental techniques such as manometry, electromyography and endoscopy, in the diagnostic workup of these patients. Moreover, it can recognize other alterations, such as incontinence and rectocele, which can be submitted to surgical correction with rectopexy.