Constipation

See Anorectal Physiology Testing for the diagnostic toolkit referenced below, and Rectocele / Rectal Prolapse (Procidentia) / Solitary Rectal Ulcer Syndrome (SRUS) for anatomic causes of obstructed defecation that overlap with constipation workup. Substantially expanded by ASCRS Ch58 - Evaluation of Constipation and Treatment of Abdominal Component (Garrett KA, Ogilvie JW Jr), which supersedes the brief technique/medication mentions previously drawn only from Sabiston Ch52 - Pelvic Floor Disorders & Constipation.

Overview

A frequent condition, affecting more than 50% of the population over 65, though it can present at younger ages in a smaller subset — an estimated 15–20% of the North American population overall, one of the most frequent GI diagnoses in outpatient clinics (~8 million annual US physician visits, ~$19 million/year in direct healthcare costs). Several medical conditions can contribute — metabolic, endocrine, neurologic, and psychiatric disorders (see the etiology table below). In adults, new-onset constipation is always a worrisome symptom and the primary cause must be excluded — hypothyroidism and medication-induced constipation are common causes. The presence of colorectal malignancy and other causes of colonic obstruction must be excluded with colonoscopy. Acute constipation is defined as symptoms <1 week; chronic constipation as symptoms persisting ≥3 months.

Etiology and pathophysiology

Defecation depends on stool formation, colonic motor function, and pelvic floor muscle coordination — chronic constipation can be a primary disorder from interruption anywhere along this pathway (normal transit constipation, slow transit constipation, or defecatory disorders — patients can have overlapping slow transit and defecatory dysfunction requiring both to be addressed) or a secondary disorder from an identifiable cause:

• Medications: opioids, anticholinergics, tricyclic antidepressants, calcium channel blockers, diuretics, bile acid sequestrants, calcium, iron.
• Mechanical: colon cancer, external compression, ischemic/diverticular strictures, endometriosis, IBD, Hirschsprung's disease, pseudo-obstruction.
• Metabolic: diabetes, hypothyroidism, hypercalcemia, hypokalemia, hypomagnesemia, uremia, heavy metal poisoning.
• Myopathies/neuropathies: amyloidosis, scleroderma, Parkinson's disease, spinal cord injury/tumor, multiple sclerosis.
• Psychiatric: depression, other psychiatric illness, sexual abuse history, eating disorders.
• Pelvic floor: anal fissure, non-relaxing puborectalis, anal stenosis, pelvic organ prolapse.
• Other: degenerative joint disease, autonomic neuropathy, cognitive impairment, immobility, cardiac disease.

Rome IV subtyping

Once alarm symptoms and organic pathology are excluded, chronic constipation is categorized into four Rome IV subtypes:

FC and IBS-C sit on a spectrum with functional diarrhea and IBS-D/IBS-M (a "constipation ↔ diarrhea" axis crossed by a "pain/bloating" axis) — pain and bloating are classically attributed mainly to IBS-C, but Rome IV acknowledges both are present to some degree even in pure FC, just not as the predominant symptom. This distinction matters clinically: if pain/bloating predominate, surgery for slow transit constipation should be "cautiously entertained but not abandoned" rather than pursued first-line.

History, physical exam, and diagnostic testing

History should clarify what the patient means by "constipation" (frequency vs. straining vs. incomplete evacuation vs. need for manual maneuvers), duration, prior bowel habits, triggers, and alarm symptoms (sudden bowel habit change, unexpected weight loss, family history of colorectal cancer, rectal bleeding without an obvious source). Physical exam focuses on the abdomen (bloating, distention, masses) and pelvic floor (DRE for mass/stricture/impaction/rectocele, anal canal length, resting/squeeze tone, ability to relax with straining); anoscopy or proctosigmoidoscopy can screen for solitary rectal ulcer or other mucosal disease. CBC, TSH, and calcium are checked when clinically indicated; colonoscopy is reserved for alarm symptoms or age-appropriate screening — testing for slow transit or dyssynergic defecation is not indicated in all patients, only those who fail empiric therapy, with the workup tailored to symptom pattern (transit studies first for bloating/motility-predominant symptoms, manometry/defecography first for outlet-obstruction symptoms like straining/digital maneuvers).

Colonic transit testing — three techniques:

• Radiopaque markers (Sitzmarks): the simplest/cheapest method. A single capsule is ingested; retention of >5 markers (20%) on day-5 abdominal X-ray diagnoses slow transit constipation. Reliable for that binary diagnosis, but the number of retained markers does not correlate with symptom severity or quality of life, and clustering at the rectosigmoid (suggestive of dyssynergic defecation) has been challenged by subsequent studies. Reproducibility is also limited — in one 51-patient study, 31% had disparate results on a repeat transit study.
• Radionuclide gamma scintigraphy: tracks radioisotope from cecal instillation to defecation over 24–48 hours (vs. 5–7 days for markers) — useful when a patient can't stay off laxatives that long; can also assess gastric emptying and small intestinal transit concurrently. Shows >80% agreement with both the marker test and the wireless capsule for discriminating normal vs. slow transit.
• Wireless pH-pressure capsule (SmartPill): determines small-bowel and colonic emptying via pH change; may help discriminate constipation subtypes (motor activity may be greater in IBS/"painful" constipation than "painless" slow transit constipation) and also measures gastric emptying/small intestinal transit.
• Colonic manometry: an invasive, not-widely-available intraluminal pressure study (catheter to the ileocecal junction via the anus) — a pediatric diagnostic standard, useful in adults as an adjunct to distinguish colonic neuropathy from myopathy when selecting surgical candidates.

Pelvic floor testing — anorectal manometry, balloon expulsion testing, and barium/MR defecography (see Anorectal Physiology Testing for full technique detail) assess for a defecatory/outlet-obstruction component, which can coexist with slow transit constipation and change surgical candidacy (see below).

Medical management

Treatment starts with patient education and elimination of secondary causes, then behavioral modification (increased dietary fiber or fiber supplementation, increased fluid intake, regular exercise, adequate time for bowel movements) — though the evidence behind some of these individual measures is weaker than their universal recommendation might suggest: a small study found extra fluid intake produced no difference in stool output, and a meta-analysis of 9 RCTs could not definitively establish exercise's effect on constipation (despite epidemiologic data that sedentary people report constipation 3× more often).

Fiber: 20–30 g/day recommended; insoluble fiber accelerates transit by increasing stool mass and direct motility/secretion stimulation, soluble fiber via hydrophilic/osmotic fermentation byproducts. Bloating/distention/flatulence limit compliance. Patients with slow transit constipation and pelvic floor dysfunction are less likely to respond to fiber alone.

Laxatives (first-line, cheap, OTC):

• Docusate sodium — limited supporting data despite common use; inferior to psyllium in a 170-patient double-blind RCT.
• Osmotic laxatives (PEG, magnesium citrate, sodium phosphate, lactulose/sorbitol) — extract fluid into the lumen via hypertonicity. A Cochrane review of 10 RCTs found PEG superior to lactulose for stool frequency, consistency, and abdominal pain; among non-absorbable carbohydrates, lactulose and sorbitol have similar efficacy but lactulose caused more nausea in a randomized crossover trial.
• Stimulant laxatives (bisacodyl, sodium picosulfate, senna/cascara/aloe) — decrease water absorption and stimulate motility/prostaglandin release; limited by abdominal pain/diarrhea and by physician concern about long-term colonic damage. That concern is not evidence-based: melanosis coli (a lipofuscin-related mucosal pigmentation from chronic anthraquinone use) is cosmetic, reversible on discontinuation, and of unknown functional significance — there is no evidence stimulant laxatives permanently harm the colon.

Secretagogues (net ion/water efflux into the lumen): lubiprostone (chloride-channel activator) beat placebo in a 4-week RCT (nausea most common side effect); linaclotide and plecanatide (minimally-absorbed guanylate cyclase-C agonists) have similar efficacy/tolerability to each other, with diarrhea as the main adverse effect (treatment discontinuation in <5%); tenapanor (FDA-approved 2019, a first-in-class GI sodium-hydrogen exchanger-3 inhibitor) beat placebo in phase 2/3 trials. This resolves the wiki's prior "no primary trial data" gap for lubiprostone/linaclotide (though prucalopride's own trial data is covered separately below, and plecanatide/tenapanor trial data is new to the wiki).

5-HT4 agonists (stimulate peristalsis/GI transit): tegaserod beat placebo in two RCTs but was withdrawn from market in 2007 over ischemic cardiovascular event concerns; the FDA re-approved it in April 2019 for women <65 without ischemic cardiovascular history and ≤1 cardiovascular risk factor, after re-examining the withdrawal data. Prucalopride (greater 5-HT4 selectivity) was superior to placebo for achieving ≥3 spontaneous bowel movements/week in an integrated analysis of 6 RCTs (2,484 patients with functional constipation) and separately beat placebo in opioid-induced constipation; diarrhea/headache are the main side effects, typically resolving within the first week.

Opioid-induced constipation occurs in 51–87% of cancer patients and 41–57% of chronic non-cancer pain patients on opioids receiving opioids; early recognition is key. Standard laxatives first-line; for non-responders, PAMORAs (peripherally-acting mu-opioid receptor antagonists — naloxone, naldemedine, alvimopan, subcutaneous methylnaltrexone) block GI mu-opioid receptors without crossing the blood-brain barrier (preserving central analgesia, minimizing withdrawal). A 27-RCT systematic review/meta-analysis found PAMORAs more effective than placebo for OIC, with naloxone and naldemedine most efficacious and naloxone safest. Elobixibat (an ileal bile acid transporter inhibitor, inducing bile acid malabsorption → increased colonic bile acid → increased stool frequency/looser consistency) resolved constipation short-term in a Japanese phase 3 RCT and is currently approved only in Japan.

Treatment of dyssynergic defecation (functional defecation disorders)

Dyssynergic defecation (anismus, paradoxical puborectalis contraction) — the Rome IV "functional defecation disorder" subtype in the table above — results from a learned paradoxical or inadequate puborectalis/pelvic-floor relaxation pattern during attempted evacuation rather than a fixed anatomic defect, occurring in up to 40% of all constipated patients (about 4.6% of patients without IBS specifically). It is diagnosed clinically and confirmed with anorectal manometry/EMG/balloon expulsion testing — see Anorectal Physiology Testing for the four-type manometric classification — and is one of four etiology-specific treatment pathways within the broader Obstructed Defecation Syndrome (ODS) umbrella. Because the underlying problem is a muscle- contraction pattern rather than structural, first-line treatment is retraining rather than surgery.

• Pelvic floor physical therapy / biofeedback is first-line: sensory biofeedback, electrical stimulation, visual manometry, and simulated-defecation techniques teach the patient to relax rather than contract the puborectalis during straining, alongside diaphragmatic breathing. A frequent pitfall: patients referred for "physical therapy" often end up doing Kegel exercises — the opposite of what's needed — so it's worth confirming what the therapy actually consisted of before declaring it a failure. Multiple visits are needed before concluding it hasn't worked; a home-based program can substitute when a trained pelvic floor therapist isn't available, and a randomized trial found home-based biofeedback non-inferior to office-based therapy.
• Electrogalvanic stimulation (EGS): an office procedure using a rectal probe delivering galvanic current to fatigue the puborectalis, typically three times a week for the first week, twice the next week, then weekly maintenance as tolerated/needed. Evidence is mixed — most studies have not shown EGS to outperform biofeedback, possibly reflecting non-standardized administration across centers — and adverse effects include increased pain, rectal irritation, and bleeding; few centers offer it.
• Botulinum toxin A injection: reserved for symptoms refractory to physical therapy. Under anesthesia, 200 units are diluted in 6–7 mL saline across six tuberculin syringes and injected transperineally (finger-guided per rectum) into the levator ani muscle posteriorly, posterolaterally, laterally, and anterolaterally, followed by aggressive anal massage; the internal anal sphincter can also be injected if tight, with the patient warned this can cause temporary fecal incontinence. Physical therapy should continue while the toxin's effect takes hold, and injections can be repeated at roughly 3-month intervals if effective, though it's unclear whether repeat dosing loses potency over time. This is a distinct indication (and injection target) from botulinum toxin for levator ani syndrome pain, covered on Functional Anorectal Pain & Coccygodynia — the two conditions can coexist but should not be conflated.
• Puborectalis myomectomy has been described but not popularized; results are uncertain.
• Fecal diversion is a last resort for patients who fail all of the above. Patients with combined slow-transit constipation and dyssynergia are an especially difficult group, sometimes managed with colectomy for the transit component (below) followed by continued dyssynergia-specific treatment for the outlet-obstruction component.

Surgical options for slow transit constipation

The central question is whether constipation is truly medically refractory — there is no standardized definition or algorithm for this determination, which has led some authors to advocate a very cautious surgical approach (or none at all), even as colectomy rates for constipation have marginally risen in the US since the early 2000s.

Patient selection

• Colonic transit confirmation is the first step, but an abnormal transit study does not equate to worse symptoms or predict better surgical outcomes (a 159-patient study found no correlation between marker location/number and symptom severity) — transit studies should mainly be used to identify patients with normal transit (poor surgical candidates), not to predict success in those with abnormal transit. Two separately abnormal transit studies (accounting for the test's limited reproducibility) correlate with significantly better surgical outcomes than one.
• Concomitant pelvic floor dysfunction must be evaluated (anorectal manometry, EMG, or defecography) — patients with co-existing outlet obstruction on EMG/defecography have significantly worse surgical satisfaction, and rectal hyposensitivity on manometry is also associated with decreased postoperative satisfaction. However, an abnormal pelvic floor test does not categorically preclude surgery — some patients with abnormal findings still do well after colectomy/IRA, since findings may be asymptomatic or a byproduct of the constipation itself rather than its cause; all findings must be weighed in context.
• Gastric/small bowel dysmotility: delayed gastric emptying is consistently associated with worse colectomy outcomes in small retrospective series, supporting a full enteric motility workup before surgery — though small bowel transit specifically did not predict outcome in one 17-patient cohort.
• Psychiatric/psychosocial factors: higher anxiety/depression rates and a history of sexual abuse are associated with chronic constipation and may predict additional postoperative abdominal complaints (though not guaranteeing failure); cognitive behavioral therapy can help, though formal psychiatric evaluation isn't required in every case.
• Preoperative counseling: the Staller et al. 2018 multidisciplinary algorithm routes patients through transit testing → (if slow transit or dyssynergic) multidisciplinary review incorporating psychological evaluation, gastric/small bowel motility assessment, and anorectal manometry → defecography if predominant symptom is pain/bloating (favoring nonsurgical management) vs. proceeding to surgery. Preoperative abdominal pain and bloating are common in surgical candidates (per SF-36/Wexner/GI-QOL data) and improve significantly post-surgery in most series, though the degree of pain improvement specifically is less certain (one series: 41% still had abdominal pain postoperatively, yet 81% were "at least somewhat pleased" with bowel frequency).

Abdominal colectomy with ileorectal anastomosis (IRA)

Decreases colonic transit time, delivering more liquid content to the rectum for easier/more frequent evacuation. The 2016 ASCRS Clinical Practice Guidelines give a strong recommendation (low-quality evidence) for total abdominal colectomy with IRA as the procedure of choice; a 2017 Association of Coloproctology of Great Britain and Ireland review agreed colectomy may help some patients but also cautioned that patient-selection evidence remains insufficient.

• Segmental colectomy based on preoperative regional transit findings has been reported in small series but is hampered by inaccurate isolation of the "diseased" segment, small datasets, and a meaningful rate of reported failures — not currently recommended.
• Long-term outcomes are generally satisfactory in well-selected patients: Zutshi et al. found 77% remained pleased with results at a median ~11-year follow-up (most frequent morbidity: small bowel obstruction, 20%); Patton et al. similarly reported high satisfaction at a median 16-year follow-up with a 21% small bowel obstruction rate. Bowel frequency after surgery is variable (41% with 1–3 BMs/day, 18% with 7–10/day, 7% with >10/day); 29% report moderate and 21% severe incontinence by St. Mark's score in one series — a real functional trade-off patients need counseling on.
• Anastomotic variants: to reduce postoperative diarrhea/incontinence risk, some centers preserve the ileocecal valve via anti-peristaltic cecorectal anastomosis, cecorectal anastomosis with colonic bypass (no colectomy), or a side-to-side ascending-colon-to-rectum anastomosis (Jinling procedure). Comparative data is limited; one 20-vs-35-patient comparison of antiperistaltic cecorectal vs. standard IRA found no difference in Wexner/Cleveland Clinic/GI-QOL outcomes.
• Megarectum caveat: when constipation coexists with megarectum (contrast-enema dilation >6.5 cm at the pelvic brim) or rectal inertia, abdominal colectomy has been associated with worse outcomes, particularly recurrent constipation. Small series suggest restorative proctocolectomy with Ileal Pouch-Anal Anastomosis (IPAA) may improve quality of life in this subgroup, but even in one 15-patient series, 13% required eventual pouch excision — the ASCRS CPG committee explicitly warns that available evidence does not justify IPAA for constipation and it should only be offered after all other options are exhausted, with anal/pelvic floor relaxation confirmed first.

Less invasive alternatives

• Transanal irrigation (TAI): regular retrograde colonic irrigation, established for neurogenic constipation/obstructed defecation and expanded to chronic refractory constipation. A 102-patient study (500–1000 mL water, ~3×/week) found 63% moderately/much improved at 12 months and 53% still performing irrigations; other studies report lower success (34–45%) in chronic constipation specifically. High discontinuation rates require appropriate training/follow-up for success.
• Antegrade continence enemas (ACE): antegrade irrigation via appendicostomy or other conduit, more established in pediatrics but increasingly used in adults. A 2016 systematic review of 209 adult patients found 68% successful at a median 39-month follow-up (though outcome measures were largely unvalidated); a Dutch cohort found only 37% success with no long-term QOL difference from controls. Surgical revision rates for stenosis/leakage are high even at specialized centers (reoperation up to 90%) — the ASCRS guidelines reserve ACE for highly selected, motivated patients.

Less standard approaches

• Sacral neuromodulation (SNM): physiologic data show S3/S4 stimulation increases distal colonic transit/contractility, but SNM lacks FDA approval for constipation; outside-US retrospective series report disappointing longer-term success (5–30%). A key methodologic limitation is that studies group all constipated patients together rather than separating abdominal (slow-transit) from pelvic (outlet-obstruction) phenotypes, which may explain the failure to identify predictors of response.
• Ileostomy creation: a reasonable option with significant fecal incontinence, high operative risk, or colectomy aversion — either as salvage after colectomy complications or as a final resort. A 2018 St. Mark's series of 24 ostomy-for-constipation patients found 64% satisfied despite lower-than-average QOL scores and a 20% reoperation rate; similar ~29% reoperation rates (stomal retraction/hernia — see Intestinal Stomas and Parastomal Hernia Repair) are reported elsewhere. Patient-selection guidance remains sparse despite surgeon familiarity with stoma creation generally.

Related pages

• Anorectal Physiology Testing — full technique detail for all diagnostic tests referenced above.
• Irritable Bowel Syndrome (IBS) — IBS-C sits on the same functional-bowel-disorder spectrum as functional constipation; see that page for IBS-C-specific pharmacotherapy (largely the same secretagogue/5-HT agents used here).
• Pediatric Colorectal Disorders — the pediatric-specific presentation, workup (sitz marker studies, colonic manometry), and surgical/cecostomy management ladder for childhood constipation, including its distinct epidemiology and the pediatric caveat that SNS for constipation alone has a high failure rate.
• Obstructed Defecation Syndrome (ODS) — the umbrella entity this page's dyssynergic-defecation section is one of four etiology-specific treatment pathways within.
• Rectocele, Rectal Prolapse (Procidentia), Solitary Rectal Ulcer Syndrome (SRUS) — anatomic causes of obstructed defecation overlapping with the defecatory-disorder subtype above.
• Functional Anorectal Pain & Coccygodynia — levator ani syndrome, a distinct condition also treated with botulinum toxin A, but for pain rather than dyssynergic defecation.
• Ileal Pouch-Anal Anastomosis (IPAA) — the megarectum-specific surgical option noted above, with the ASCRS CPG's explicit caution against its routine use for constipation.
• Intestinal Stomas, Parastomal Hernia Repair — full detail on ileostomy creation/ complications referenced in the "less standard approaches" section above.

Open items / gaps

• ~~No primary trial data on the newer constipation medications (lubiprostone, linaclotide, prucalopride) referenced above by brand name.~~ Resolved by ASCRS Ch58 - Evaluation of Constipation and Treatment of Abdominal Component at the textbook/secondary level (specific RCTs now named for lubiprostone, linaclotide, plecanatide, tenapanor, prucalopride) — none of the individual trials have been independently ingested from their primary publications, which would be the next step if deeper verification is wanted.
• ~~No detail on how anismus (paradoxical puborectalis contraction, diagnosed by EMG per Anorectal Physiology Testing) is specifically treated (e.g. biofeedback protocols) — worth a dedicated source.~~ Resolved by ASCRS Ch59 - Treatment of Difficult-Obstructive Defecation — see the new "Treatment of dyssynergic defecation" section above (physical therapy/biofeedback, EGS, botulinum toxin A, myomectomy, fecal diversion).
• No standardized definition exists in the literature for "medically refractory constipation" meriting surgical referral — explicitly flagged as a field-wide gap by Ch58 itself, not just a wiki gap.
• Several individually load-bearing RCTs/analyses are flagged in Research Priorities.md as independent-verification candidates given how much of this page's medical-management section now rests on them.