Fecal Incontinence

Disorders of the continence and defecation mechanisms described on Anorectal Physiology; the diagnostic workup draws on Anorectal Physiology Testing. Pathophysiology below is from a textbook reference chapter (ASCRS Ch03 - Anorectal Physiology); the Evaluation and Treatment sections below are from the dedicated fecal incontinence chapter, ASCRS Ch61 - Fecal Incontinence Evaluation and Treatment, which the Ch03 source had explicitly deferred to.

Fecal incontinence

Usually defined as uncontrolled passage of feces or gas over at least one month's duration in someone who previously had control. Estimated prevalence varies widely by definition, method, and population studied — an up-to-date systematic review of 4,840 articles found rates ranging 1–19%. Severity varies widely too, but the condition carries a significant quality-of-life burden: reduced quality of life, depression, and social stigma are all associated.

Continence requires integrated, coordinated mental, anatomic, and physiologic function — reflexes, sensory/motor nerves, and the muscles of the rectum, sphincters, and pelvic floor. Disorders can derive from a deficit in any of these, or simply from high stool volume/liquid consistency even with normal anatomy/function. Because continence mechanisms are somewhat redundant, isolated deficits are often tolerated without symptoms until decades later — e.g., obstetric-trauma effects may only become symptomatic once compensatory mechanisms weaken with age. Fecal incontinence is therefore most often multifactorial, spanning four broad etiologic categories: anatomical (sphincter trauma, rectal prolapse/intussusception, imperforate anus), neurologic (pudendal neuropathy, CNS disease), stool characteristics (diarrhea, constipation with overflow), and rectal (radiation proctitis, post- LAR/coloanal-anastomosis changes) — detailed by mechanism in the subsections below.

Sphincter-defect incontinence: iatrogenic (sphincterotomy — see Anal Fissure for lateral internal sphincterotomy's specific 8–30% incontinence rate and the traditional-vs-tailored technique trade-off, fistula surgery — see Anal Fistula for fistulotomy/cutting-seton-specific incontinence rates, which can run as high as 0–67% for cutting setons, hemorrhoidectomy — see Hemorrhoids for hemorrhoidectomy-specific incontinence rates/mechanism) or obstetric/traumatic sphincter injury (see Rectal Prolapse (Procidentia) for the prolapse-specific version of this mechanism).

Idiopathic incontinence (no defined functional bowel disorder or anatomic deficit) is most commonly associated with pelvic floor/sphincter denervation — itself idiopathic (associated with advanced age), or secondary to obstetric trauma, chronic straining, constipation-related distention, or outlet dysfunction. Decreased sphincter pressures are seen in older adults, especially women after menopause; PNTML is also prolonged in older women. Compared to continent individuals, idiopathic fecal incontinence patients show more pelvic floor motor neuropathy (lower anal resting/voluntary contraction pressures, longer PNTML, higher mucosal electrosensitivity thresholds) — evidence motivating sacral and posterior tibial nerve stimulation as therapy, since both can influence sensory and motor anorectal innervation.

Neurologic incontinence: in spinal cord injury and other neurologic disease, loss of rectal sensation may impair RAIR (see Anorectal Physiology), while exaggerated unopposed distention- triggered sphincter relaxation and impaired spinal reflex activity can reduce rectal compliance — incontinence in this setting can derive from any combination of decreased anal resting tone, loss of voluntary control, or loss of anorectal reflexes, depending on injury level/completeness.

Disorders of defecation

In constipation with anal outlet dysfunction, physiologic abnormalities include inadequate defecatory propulsion, dyssynergic defecation, or both — see Constipation for the clinical/surgical side of slow-transit constipation. Idiopathic outlet dysfunction may show elevated anal resting pressures (inconsistently), impaired rectal sensation or decreased RAIR (also inconsistently reported), or decreased rectal tone/intrarectal pressure with straining (consistent with diminished propulsion contributing to outlet dysfunction). New-onset constipation after hysterectomy with decreased rectal sensory perception implicates injury to the parasympathetic plexus reaching the rectum via the lateral vaginal walls during lateral pelvic dissection.

In other patients, obstructed defecation results from dyssynergic contraction of the EAS and/or puborectalis during evacuation efforts — clinically significant limitation of emptying despite adequate rectal pressure with straining, demonstrated by EMG showing paradoxical puborectalis contraction during straining/Valsalva ("anismus" — see Constipation's Rome IV section and Anorectal Physiology Testing's EMG description for the same finding). One cited study found no difference in perineal descent or manometric EAS assessment between incontinence and obstructed- defecation patients — the anatomic/physiologic correlates of defecatory disorders don't reliably predict the clinical syndrome.

Anorectal pain

In the absence of an identifiable anatomic source (trauma, fissure, thrombosed hemorrhoid — see Hemorrhoids for full presentation/management — abscess, tumor), idiopathic/functional anorectal pain disorders can occasionally follow anorectal surgery but are more commonly associated with psychological disturbance, including anxiety and post-traumatic stress; manometry/other physiologic testing findings are variable in these patients. Full Rome IV subtyping (levator ani syndrome, unspecified functional anorectal pain, proctalgia fugax), diagnostic criteria, and the complete treatment ladder for each now live on Functional Anorectal Pain & Coccygodynia, which also covers coccygodynia and cross-references Pudendal Neuralgia as a related entrapment neuropathy.

Urogynecological considerations

Functional defecatory disorders (fecal incontinence, obstructed defecation, rectal prolapse, rectocele, enterocele, sigmoidocele, anorectal pain) frequently coexist with urogynecologic conditions — urinary incontinence/retention, uterine prolapse/procidentia, chronic pelvic pain — likely from shared pelvic floor/urogenital diaphragm musculature and overlapping peripheral innervation/spinal nerve roots. (The source defers detailed cross-specialty management to a not-yet-ingested chapter.)

Evaluation

History and physical exam are the starting point, identifying likely cause(s) and directing counseling/management. Assess bowel habit frequency, diarrhea/constipation, recent changes, and medications; review comorbidities (diabetes, neurologic conditions, IBS, IBD, prior radiation, rectal prolapse) and concomitant urinary symptoms or anterior prolapse; document obstetric/surgical history (episiotomy, colectomy, anorectal procedures). Exam includes perianal inspection (rash, scars, trauma, fistula, patulous anus, prolapsing hemorrhoids/rectal prolapse — have the patient bear down to check for prolapse and descending perineum), sensory testing (cotton ball/sharp object) and the anocutaneous reflex ("anal wink," suggesting an intact sacral reflex arc), and digital exam of resting tone/squeeze, gluteal substitution, rectocele, and perineal body thickness. The Cleveland Clinic Florida Fecal-Incontinence Score (CCF-FIS) is a simple, validated 0–20 scoring tool (0 = perfect continence) covering solid/liquid/gas incontinence frequency, pad use, and lifestyle impact, used throughout the outcome literature cited below.

Anorectal manometry (see Anorectal Physiology Testing for full technique) measures internal/ external sphincter pressure, sphincter length, sensation, compliance, and the RAIR — though it may not always correlate with exam findings or predict treatment response, it can still help guide therapy. Low internal sphincter pressure is associated with leakage/passive incontinence; low external sphincter pressure with urgent/active incontinence. Sphincter pressures can be normal or even increased in anismus/incomplete evacuation, especially in men with FI. Rectal hyposensitivity can drive constipation-associated incontinence, while rectal hypersensitivity is seen with urgency, diarrhea, IBS, Low Anterior Resection Syndrome (LARS), or radiation. Absent RAIR suggests Hirschsprung's disease, prior anorectal surgery, or connective tissue disorders (and can be difficult to elicit when resting pressures are already low); compliance is reduced in IBD, post-radiation, or scleroderma.

Ultrasound: anal ultrasound objectively assesses sphincter integrity/anatomic deficiencies and is inexpensive and widely available, offering the best internal-sphincter imaging. MRI is an alternative, particularly for the anterior external sphincter or concomitant pelvic prolapse; in experienced hands, combined transperineal/transvaginal pelvic floor ultrasound can image all three pelvic compartments and identify pelvic organ prolapse.

Neurophysiology testing: PNTML and EMG assess neuromuscular integrity, but — consistent with the methodologic criticism already detailed on Anorectal Physiology Testing — a prolonged PNTML does not independently predict treatment success, and the technique "has slowly faded away as a diagnostic modality." Needle EMG sphincter mapping can identify defects/denervation but causes significant discomfort and is now infrequently used.

Defecography (fluoroscopic or MRI) confirms inability to retain stool (an FI severity measure) and identifies impaired evacuation or pelvic organ prolapse contributing to FI. A demonstrated rectal intussusception is a negative predictor for sacral neuromodulation success — these patients may instead be candidates for ventral rectopexy. Incomplete evacuation and anismus are associated with anal leakage, especially in men.

Colonoscopy per standard screening guidelines and in patients with bowel symptoms, to exclude malignancy/IBD; in older women with diarrhea specifically, biopsies should be taken to rule out microscopic colitis (see Microscopic Colitis).

Treatment

Goals: decrease frequency/severity of FI episodes and improve quality of life — most treatments rarely achieve complete resolution, so most patients start with conservative measures before escalating.

Conservative treatment

First-line: dietary modification (avoiding sweeteners, dairy, caffeine, and other FI-aggravating medications/foods), antidiarrheals, cholestyramine, and/or fiber supplementation to bulk stool. Bowel management with enemas/suppositories reduces rectal stool volume between episodes; a newer anal irrigation system (Peristeen™) has shown symptom/quality-of-life improvement specifically in Low Anterior Resection Syndrome (LARS) patients.

Pelvic floor exercises/biofeedback are first-line active therapy. Evidence is mixed — some studies show no advantage over advice/education alone, but a Cochrane review found biofeedback plus electrical stimulation may outperform either alone. A 124-patient study (Regadas et al.) found a 50% FI-score reduction in about half of patients; predictors of poor response included a CCF-FIS ≥10, prior vaginal delivery, prior anorectal/colorectal surgery, and inability to sustain a squeezing effort.

Anal insertion device (e.g. Renew): a patient-inserted rectal plug blocking involuntary stool passage — adjunctive to conservative therapy, though a Cochrane review notes plugs can be difficult to tolerate. A multicenter study of a soft silicone insert found 77% of completers (62% of intention-to-treat patients) achieved ≥50% reduction in incontinence frequency over 12 weeks, with greater benefit in milder FI.

Vaginal bowel control system (Eclipse): a vaginally-placed balloon/pump device that occludes the rectum via the vaginal wall, deflated for defecation. In a multicenter open-label trial, only 62% of 137 patients could be fitted; of 73 moderate-FI patients (mean CCF-IS 14.1) who could keep the device, 94% achieved success at 12 months with significant quality-of-life improvement.

Sacral neuromodulation (SNM)

The most common minimally invasive treatment for moderate/severe FI. Originally offered only to patients with an intact or minimally defective external sphincter, but indications have widened — patients with or without a sphincter defect now achieve similar results. Mechanism is not fully understood (proposed: somatovisceral reflex stimulation, direct sphincter effect, afferent neuromodulation). Performed in two stages: a 1–2 week trial lead (percutaneous/PNE in-office, or a surgically-placed quadripolar lead — PNE may have a slightly higher failure rate, quadripolar placement a slightly higher infection risk) to confirm ≥50% improvement in FI episodes, then permanent implantation.

The US multicenter FDA-approval trial found, of 120 permanently implanted patients: 83% achieved ≥50% reduction in incontinent episodes at 1 year, 41% achieved complete continence, and results were sustained at 5 years (89% with ≥50% improvement, 36% complete continence). A 7-year European cohort found 71.3% sustained success among patients retaining the device. Complications (pocket/lead issues, infection, pain, loss of efficacy) are usually manageable conservatively, but reoperation rates can reach 42% and devices need replacement every 3–5 years; a newer rechargeable device (up to 15 years, full-body-MRI-conditional-safe) shows comparable results to the original system.

Bulking agents

NASHA Dx (nonanimal stabilized hyaluronic acid/dextranomer gel), FDA-approved in 2011 for submucosal injection above the dentate line. The largest RCT to date (vs. sham) found treatment success (≥50% episode reduction) in 52% vs. 31% (P = 0.0089), sustained at 36 months with quality-of- life improvement; a separate RCT found no difference vs. biofeedback. Its overall role remains unclear, but in practice it's most used for mild/moderate FI, male patients (especially with soiling), residual incontinence after SNM, and postoperative "keyhole" sphincter defects.

Percutaneous tibial nerve stimulation (PTNS)

Thought to affect anorectal neuromuscular function similarly to SNM via shared sacral segmental innervation. Earlier uncontrolled series reported 63–82% success, but a UK double-blind RCT (227 patients) found no significant difference vs. sham at 12 weeks, and a systematic review comparing PTNS with SNM found SNM associated with better functional outcomes and quality of life.

Radiofrequency energy delivery (SECCA®)

Delivers radiofrequency energy into the internal anal sphincter to stimulate collagen deposition/ thickening, increasing outlet resistance — an option for mild-to-moderate FI with intact or limited sphincter defects. Pooled outcomes across several studies found 55–80% of patients responders at 12 months, though with limited CCF-FIS improvement and variable long-term durability (one study: 22% maintained improvement without reintervention at 3 years; another: only 6%). A sham-controlled RCT found a statistically significant Vaizey score decrease, but only 2 of 40 patients met the clinically-relevant-improvement threshold. The ASCRS clinical practice guidelines endorse SECCA as an option but recommend trying alternative treatments first.

Stem cell therapy

Investigational (not FDA-approved for FI); postulated to regenerate damaged striated sphincter muscle or accelerate healing, using muscle-, bone-marrow-, or adipose-derived cells. An initial 10-patient myoblast-injection study in obstetric-injury FI found sustained CCF-IS improvement (mean 13.7-point decrease) and quality-of-life gains at 12 months and 5 years, without a change in squeeze pressure (suggesting a non-contractile mechanism of benefit). A phase II randomized, double-blind, placebo-controlled myoblast trial (12 vs. 12 patients) found continued improvement in the treatment arm at 12 months where the control arm plateaued, with no severe adverse events.

Anal sling (TOPAS)

The Transobturator Posterior Anal Sling loops polypropylene mesh tape posterior to the anal canal via a minimally invasive needle-based delivery system, correcting pelvic floor support/anorectal angle. A 152-patient multicenter study found ~70% of women achieved ≥50% episode reduction at 1 year with quality-of-life improvement (19% complete continence), though 66 patients reported adverse events (most commonly pelvic pain). Not available in the USA.

Surgical sphincter repair (overlapping sphincteroplasty)

Obstetric sphincter injury is a common cause of FI in women of childbearing age — occult defects are found by anal ultrasound in >30% of primiparous and >40% of multiparous women, especially after forceps delivery. Sphincteroplasty is an option for younger patients with a defined sphincter defect (e.g. obstetric injury), and can concurrently correct a thinned perineal body or rectovaginal fistula.

Performed under general anesthesia, typically prone jackknife: a curvilinear perineal incision, with dissection carried laterally to identify the sphincter on each side; the scarred sphincter ends are divided and overlapped with mattress sutures, adding bulk to the sphincter complex. A levatorplasty can be added when appropriate. Separately imbricating the internal sphincter has not been shown to add durability beyond the overlap repair itself.

Short-term (<5 year) results are usually good (70–90% improvement rates), but few patients are completely symptom-free and results often deteriorate over time — even so, patient satisfaction tends to remain relatively high despite that symptomatic deterioration.

Ventral mesh rectopexy (for prolapse/intussusception-associated FI)

Patients with external rectal prolapse or significant rectal intussusception frequently have FI symptoms. See Rectal Prolapse Repair for full ventral mesh rectopexy (VMR) technique — this section covers FI-specific outcome data. A systematic review (Samaranayake et al.) found an overall 45% decrease in FI score alongside significant constipation-symptom improvement, and VMR has gained widespread acceptance in Europe as the rectal-prolapse treatment of choice partly on this basis. Some centers have expanded VMR's indications to advanced internal prolapse (Oxford grades III–IV — see Rectal Prolapse (Procidentia) for the grading system) presenting with combined FI and outlet obstruction symptoms, though more comparative studies against other prolapse repairs are still needed. Complication profile (mesh erosion, stricture, rectovaginal fistula, pudendal-irritation pelvic pain) mirrors what's detailed on Rectal Prolapse Repair; long-term follow-up specifically for the FI indication remains limited.

Gracilis muscle transposition (dynamic graciloplasty)

Transposes the gracilis muscle (easily harvested, single proximal vascular pedicle) around the anus; an implanted intramuscular electrode can retrain the naturally fast-twitch, fatigable muscle into a slow-twitch, fatigue-resistant one via electrical stimulation. Demonstrated good effect in some patients, but complications (surgical site infection, pain, device problems, erosion, outlet obstruction) were common. Dynamic graciloplasty is not currently available.

Magnetic anal sphincter augmentation (Fenix™)

FDA humanitarian-device-exemption approval for FI refractory to medical/surgical management: magnetic beads on a titanium string are placed around the sphincter, providing outlet resistance at rest while separating (under rectal pressure/Valsalva) to permit defecation. Limited literature reports favorable FI-score improvement with about half of patients successful at 5 years; complications include infection, pain, gluteal swelling, and occasional explantation. Not currently available.

Artificial bowel sphincter (ABS)

An implanted cuff around the anus connected to a pump (in the labia majora or scrotum) and a fluid reservoir in the space of Retzius — compressing the pump deflates the cuff to allow defecation. Studies show solid results (~60–70% success) in end-stage FI, but high infection/erosion rates often necessitate revision or explantation. No longer available in the USA.

Treatment failure

When the above fail, a well-constructed ileostomy or colostomy can substantially improve quality of life. For selected motivated patients, a Malone antegrade colonic enema (MACE) — a reverse appendicostomy or cecostomy allowing antegrade colonic flushing — is an alternative. A systematic review of 374 MACE-for-FI-and-constipation patients found 47–100% still using their stoma despite the time commitment, with soiling/leakage problems in some and a stoma stenosis rate of 8–50% sometimes requiring reintervention.

Overall: treatment should be tailored to the individual patient based on FI severity, anatomic abnormalities, and patient expectations — there is no single best option across this ladder.

Related pages

• Anorectal Physiology — the normal mechanisms this page's disorders represent failures of.
• Anorectal Physiology Testing — the diagnostic toolkit used to evaluate these disorders.
• Constipation — slow-transit constipation and anismus/dyssynergic defecation overlap substantially with this page's Disorders of Defecation section.
• Rectal Prolapse (Procidentia) — its own fecal-incontinence discussion (conduit effect, sphincter stretching, RAIR stimulation by prolapsed tissue, pudendal neuropathy) is the prolapse-specific case of the general mechanisms described here.
• Functional Anorectal Pain & Coccygodynia and Pudendal Neuralgia — full detail on the anorectal pain disorders only briefly noted above.
• Rectal Prolapse Repair — full ventral mesh rectopexy technique underlying this page's prolapse/intussusception-associated FI treatment section.
• Low Anterior Resection Syndrome (LARS) — anal irrigation (Peristeen™) and rectal hypersensitivity overlap noted in this page's Evaluation/Treatment sections.

Open items / gaps

• ~~Diagnostic algorithms and specific management strategies for fecal incontinence itself (sphincteroplasty, sacral nerve stimulation protocols, biofeedback for dyssynergic defecation) are still deferred by the source to later chapters.~~ Resolved by ASCRS Ch61 - Fecal Incontinence Evaluation and Treatment — see the new Evaluation and Treatment sections above for the full ladder (conservative measures, biofeedback, SNM, bulking agents, PTNS, SECCA, stem cell therapy, TOPAS, sphincteroplasty, VMR, dynamic graciloplasty, MAS, ABS, and last-resort diversion/MACE).
• No primary literature yet independently ingested for any of the named RCTs/systematic reviews cited above (NASHA Dx trial, the SNM FDA-approval trial, the PTNS sham RCT, etc.) — several are flagged in Research Priorities.md.
• Several device options described (TOPAS, dynamic graciloplasty, Fenix MAS, ABS) are explicitly not currently available in the USA — worth flagging in any patient-facing counseling context, not just as an academic footnote.