Rectal Prolapse (Procidentia)
See Anorectal Physiology Testing for the diagnostic toolkit referenced throughout, Fecal Incontinence for the general (non-prolapse-specific) mechanisms of the incontinence described below, Rectal Prolapse Repair for operative technique detail, and Obstructed Defecation Syndrome (ODS) for how the internal/intrarectal prolapse mentioned below fits within the broader obstructed-defecation umbrella (distinct from — but on the same spectrum as — the external prolapse this page focuses on). Content below is from textbook reference chapters (Sabiston Ch52 - Pelvic Floor Disorders & Constipation and ASCRS Ch60 - Rectal Prolapse), not primary literature except where a specific study is named.
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. The mechanism itself remains poorly understood; one long-standing theory (Broden and Snellman) holds that full-thickness prolapse is initiated by mid-rectal intussusception that progresses down through the anal canal. Connective tissue disorders have been proposed as a contributing factor, especially in younger patients. Multicompartment pelvic organ prolapse — suggesting a generalized pelvic tissue weakness rather than a purely rectal problem — may also contribute to progressive posterior compartment deterioration and eventual rectal prolapse.
It's important to distinguish three related but distinct anatomic entities that are sometimes conflated: rectal mucosal prolapse (only the rectal/anal mucosa protrudes through the anus), internal rectal intussusception (the full rectal wall telescopes toward the anal canal without protruding through it — see Obstructed Defecation Syndrome (ODS)), and full-thickness (overt) rectal prolapse, this page's focus. The underlying mechanism may be shared across all three, but treatment options differ. The Oxford rectal prolapse grading system formalizes this spectrum radiologically (on defecography or exam), from low-grade internal prolapse through overt prolapse:
| Oxford grade | Radiological characteristic |
|---|---|
| I (low grade, internal) | Descends no lower than the proximal limit of the rectocele |
| II (low grade, internal) | Descends into the level of the rectocele, but not into the anal canal |
| III (high grade, internal) | Descends into the proximal anal canal |
| IV (high grade, internal) | Descends into the distal anal canal |
| V (overt rectal prolapse) | Protrudes from the anus |
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.
Concomitant pelvic organ prolapse is common: 20–35% of rectal prolapse patients also report urinary incontinence, and 15–30% have significant vaginal vault prolapse (Jackson et al.) — reinforcing why a multidisciplinary evaluation is increasingly recommended (see Rectal Prolapse Repair and, for the full urogynecologic-side evaluation/staging and procedure detail, Pelvic Organ Prolapse (Anterior & Middle Compartment)).
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 — Hemorrhoids (ASCRS Ch11) makes the identical distinction from the hemorrhoid-disease side. 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 defecography is the most useful test to characterize the dynamic pelvic anatomy during defecation and confirm coexisting disorders — rectocele, cystocele, vaginal vault prolapse, enterocele, and sigmoidocele — since physical exam alone cannot assess the extent of internal pelvic organ collapse with evacuation. Dynamic MRI defecography (dMRD) is an alternative, but is performed supine (less physiologic than sitting) and a systematic review/meta-analysis (Ramage et al.) found it significantly less sensitive than fluoroscopic defecography, with higher miss rates for intussusception/prolapse and reduced detection of small rectoceles and vaginal vault descent. 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.
Anorectal physiology testing (manometry, EMG — see Anorectal Physiology Testing for full technique) helps characterize baseline sphincter function before surgery, useful for counseling patients on expected postoperative continence or the potential need for postoperative pelvic floor physical therapy. Repeated stretching of the anal sphincter complex by the prolapsing tissue typically causes low resting/squeeze pressures and diminished squeeze recruitment. EMG results can be misleading in this population: a paradoxical increase in EMG activity with Valsalva can occur due to mounting pressure from the prolapsing tissue itself, mimicking the EMG pattern of pelvic floor dyssynergia (see Constipation) — clinical correlation is essential before attributing this to true dyssynergia.
Patient questionnaires: validated instruments help set expectations (functional symptoms like incontinence or constipation can evolve for months after surgery) and objectively track outcomes. Given how broad the range of rectal-prolapse/multicompartment-POP symptoms can be, the Pelvic Floor Disorders Consortium's 2019 consensus recommends a combined instrument, IMPACT (Initial Measurement of Patient-Reported Pelvic Floor Complaints Tool), which captures multiple patient-reported prolapse symptoms and their evolution over time, rather than relying on a single narrower symptom-specific survey.
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.~~ Substantially resolved by ASCRS Ch60 - Rectal Prolapse — see Rectal Prolapse Repair for the now much richer comparative-outcomes evidence (RCT, registry, and meta-analysis data on recurrence/mortality/ complications across techniques), though still all known secondhand via the textbook's citations rather than independently ingested from primary sources.
- No incidence/prevalence update beyond the ~0.5% figure above — worth checking whether more recent epidemiologic data exists if a primary source is ever ingested for this page.