Rectal Prolapse (Procidentia)

See Anorectal Physiology Testing for the diagnostic toolkit referenced throughout, and Rectal Prolapse Repair for operative technique detail. Content below is from a textbook reference chapter (Sabiston Ch52 - Pelvic Floor Disorders & Constipation), not primary literature.

Anatomy and pathophysiology

Rectal prolapse is a circumferential, full-thickness intussusception of the rectal wall. Degree of prolapse ranges from intrarectal/internal prolapse, to intra-anal prolapse, to external rectal prolapse. An uncommon condition, occurring in about 0.5% of the general population, with women over 50 about 6 times more likely than men to develop it. The few men who present are usually younger than 40. Young patients (both sexes) with prolapse often suffer from psychiatric disease (such as autism or developmental delay) and take constipating medications.

The cause is still unknown, but some anatomic defects are commonly found in patients with total rectal prolapse: diastasis of the levator ani muscle, an abnormally deep cul-de-sac, a redundant sigmoid colon, a patulous anus, and lack of fascial attachments of the rectum against the sacrum.

Risk factors: age over 40, female gender, prior pelvic surgery, chronic straining/constipation, chronic diarrhea, vaginal delivery and multiparity (though a third of female rectal prolapse patients are nulliparous), pelvic floor dysfunction and/or anatomic defects, neurologic diseases/injuries, and psychiatric disease requiring constipating medications.

Rectal prolapse usually has a progressive course — from transient, self-reducing prolapse during defecation, to prolapse requiring digital self-reduction, to a stable prolapse that may present with ulceration and even nonreducible, incarcerated prolapse with necrosis in the most advanced/ complicated cases.

Symptoms

Discomfort from the prolapsed tissue, incontinence with drainage of mucous or blood, and constipation. 50–75% of patients with evident rectal prolapse complain of fecal incontinence (passive or urge incontinence), caused by a direct conduit effect, chronic stretching of the sphincter from the prolapse, and persistent stimulation of the rectoanal inhibitory reflex by the prolapsed rectum. Up to half of patients with incontinence also have pudendal neuropathy (a prolonged pudendal nerve terminal motor latency). The other 25–50% of patients — particularly those with intrarectal prolapse — report constipation or obstructed defecation (a sensation of incomplete rectal evacuation) resulting from the “telescoping” of the bowel on itself, creating a functional blockage that worsens with straining, or from a concomitant rectocele.

Diagnosis and differential diagnosis

On physical exam, true rectal prolapse must be differentiated from prolapsed rectal mucosa or prolapsed hemorrhoids: full-thickness rectal prolapse has concentric folds, whereas prolapsed hemorrhoids/rectal mucosa show radial folds with grooves along the hemorrhoid cushions. At rest, typical findings include a patulous anus with a lax sphincter. Exam is performed with the patient in standard left lateral decubitus, or sitting/squatting during straining; if prolapse can’t be observed in the office, the patient can be asked to take a “selfie” at home documenting it.

Proctoscopic exam demonstrates redundant tissue and, in 10–15% of patients, an anterior solitary rectal ulcer (see Solitary Rectal Ulcer Syndrome (SRUS)) — proctoscopy may show erythema at 5–6 cm, the leading edge of the prolapse. Fluoroscopic or MRI defecography is an additional test to confirm the diagnosis and provides more information on coexisting disorders — rectocele, cystocele, vaginal vault prolapse, enterocele, and sigmoidocele. Colonoscopy should always be performed to exclude CRC or other colonic pathology. A colonic transit study is performed in patients with a lifelong history of constipation to differentiate constipation due to obstructed defecation from constipation due to slow colonic transit — the two frequently coexist. Endoanal ultrasound usually shows thickening of the internal anal sphincter.

Nonoperative management

Prolapse-associated symptoms of constipation and fecal incontinence can be palliated with medical treatment to improve quality of life: adequate fluid intake, fiber supplements, and stool softeners for constipation; sugar or salt applied topically to reduce rectal mucosal edema and facilitate reduction of the prolapsed tissue; enemas or suppositories to assist defecation.

Open items / gaps

• No primary trial data yet — see Rectal Prolapse Repair for the operative options and their comparative outcomes, also sourced only from this textbook chapter.