The diagnosis of full-thickness rectal prolapse is a clinical diagnosis and patients often report a wide variety of associated symptoms including bleeding, pain, urge to defecate, mucous drainage, protrusion of a mass, constipation, and incontinence. Given that these symptoms are characteristic not only of prolapse but other anorectal conditions as well, a thorough evaluation to confirm the diagnosis is warranted. Colorectal cancers and colitides are important to exclude. To identify such cases, taking a detailed history and performing a physical exam and colonoscopy is imperative on all patients who are presumed to have rectal prolapse.

To assess the prolapse, it is often useful to examine the patient sitting on the toilet. The ability to sit on the commode and strain or evacuate stool often makes it easier for the patient to produce the prolapse, thus allowing the physician to ascertain its extent and differentiate between full-thickness and mucosal prolapse. The classic finding for true rectal prolapse is protrusion of circumferential folds, oftentimes accompanied by a sulcus between the prolapsed rectum and the anal opening. In contrast, mucosal prolapse lacks a sulcus and exhibit protruding tissue with radial folds.

Constipation occurs in 25–50% of patients (2), whereas 40–70% of patients experience fecal incontinence (3). Anal manometry is useful to assess sphincter function as chronic prolapse may lead to sphincter dysfunction, particularly of the internal sphincter. The decreased pressure of the internal sphincter may be the result of chronic trauma
or may be associated with reversible activation of the rectoanal inhibitory reflex resulting from rectal distention by the prolapsed tissue (4). In addition, the rectoanal inhibitory reflex may be delayed or absent (5,6). Pudendal motor nerve latency testing may identify those patients with neurogenic fecal incontinence and endoanal ultrasound can help to distinguish between functional and anatomic etiologies (7). Given that 54% of patients with incontinence will have improvement of function with repair of their rectal prolapse, while a small percentage get worse, these tests help guide postoperative expectations (8). For patients with a history of constipation, electromyography should be obtained for those individuals with a history of severe straining and obstructive defecation as this may identify a subset of patients with puborectalis dysfunction who would benefit from biofeedback after surgery. Colonic transit studies can also identify those with colonic inertia who may benefit from an associated colonic resection at the time of prolapse repair.