Gastrointestinal

Constipation: outpatient evaluation and management

Clinical Overview and When to Suspect Constipation

— Straining

— Lumpy or hard stools (Bristol 1–2)

— Sensation of incomplete evacuation

— Sensation of anorectal obstruction/blockage

— Manual maneuvers to facilitate defecation (digital evacuation, pelvic floor support)

— Fewer than 3 spontaneous bowel movements per week

— Normal-transit (functional) — most common; perceived difficulty despite normal colonic transit

— Slow-transit — delayed colonic propulsion; younger women, infrequent urges

— Defecatory/outlet dysfunction — dyssynergia of puborectalis/anal sphincter, rectocele, descending perineum

— Secondary — drugs, endocrine (hypothyroidism, hypercalcemia, DM), neurologic (Parkinson, MS, spinal cord), obstructive (stricture, CRC), structural (rectal prolapse)

— Age ≥50 with new-onset constipation and no prior screening colonoscopy

— Hematochezia or melena, iron-deficiency anemia

— Unintentional weight loss >10 lb

— Family history of CRC or IBD

— Acute change in caliber of stool, nocturnal symptoms

— Severe, refractory symptoms or sudden worsening

Board pearl: In the outpatient setting, functional constipation is a clinical diagnosis — you do NOT need imaging or colonoscopy in a young patient without alarm features. Start with lifestyle + osmotic laxative empirically. Reserve workup for red flags, refractory cases, or age-appropriate CRC screening indications.

Step 3 management: Always reconcile the medication list at the first visit — opioids, anticholinergics, CCBs (verapamil), iron, and ondansetron are frequent culprits.

Definition (Rome IV): ≥2 of the following for ≥3 months (onset ≥6 months prior), present in >25% of defecations:

Loose stools rarely present without laxatives, and criteria for IBS are not met.

Prevalence: ~15% of US adults; 2–3× more common in women, elderly, and lower socioeconomic groups. A top-10 ambulatory complaint in family medicine.

Pathophysiologic categories — drive workup and therapy:

When to suspect a serious secondary cause — these are the Step 3 "alarm features":

Presentation Patterns and Key History

— Frequency (BMs/week)

— Bristol stool form scale (types 1–2 = constipation; type 7 = diarrhea)

— Straining time, sense of incomplete evacuation, need for digital maneuvers

— Use of laxatives, enemas, fiber supplements

— Slow-transit: infrequent urge to defecate, <1 BM/week, bloating, often young women, lifelong

— Defecatory dysfunction: frequent urge but unable to evacuate, prolonged straining, digital splinting/vaginal pressure, sensation of anal blockage

— Normal-transit: normal frequency but patient perceives difficulty; abdominal discomfort common

— Medications: opioids (any chronic pain regimen), anticholinergics (TCAs, oxybutynin, antihistamines), iron, calcium, CCBs (especially verapamil), clonidine, ondansetron, antipsychotics, sucralfate

— Endocrine: cold intolerance, weight gain, fatigue → hypothyroidism; polyuria/polydipsia → DM or hypercalcemia

— Neurologic: tremor, rigidity → Parkinson; sensory changes, urinary symptoms → cord lesion or MS

— Obstetric/surgical: vaginal delivery with tearing, hysterectomy, anorectal surgery (risk for outlet dysfunction)

Key distinction: Straining with hard stool points to slow- or normal-transit; straining with soft stool, digital splinting, or vaginal pressure strongly suggests defecatory dysfunction, which requires anorectal manometry and biofeedback, not more laxatives.

Board pearl: Always ask about opioids and OTC anticholinergics — they are the single most common reversible cause in elderly outpatients.

Open-ended start: "What do you mean by constipation?" — patients use the word for hard stools, infrequent stools, straining, or incomplete evacuation. Each implies a different mechanism.

Bowel diary elements to elicit or assign as homework:

Distinguishing the three functional subtypes by history:

Targeted secondary-cause review:

Dietary and behavioral: fluid intake, fiber intake, physical activity, recent travel, toileting habits (suppressing urges, time pressure at work)

Psychosocial: anxiety, depression, history of sexual abuse (associated with dyssynergic defecation), eating disorders

Physical Exam Findings and Anorectal Assessment

— Inspection for distention, surgical scars

— Palpable stool in left lower quadrant (sigmoid)

— Tympany suggests gas; dullness over palpable mass warrants imaging

— Tenderness, rebound, or guarding → consider obstruction, ischemia, or impaction with perforation

— Inspection: hemorrhoids, fissures, skin tags, soiling, gaping anus (neurologic), rectal prolapse with Valsalva

— Resting tone: low tone → neurogenic or post-obstetric injury

— Squeeze tone: assesses external sphincter/puborectalis strength

— Push/strain maneuver: ask patient to bear down as if defecating

— Stool in vault: hard impaction; assess for fecal impaction with overflow incontinence

— Masses, strictures, blood, prostate exam in men

Board pearl: A well-performed DRE has ~75% sensitivity for detecting dyssynergic defecation and can spare a patient months of failed laxative escalation. If the puborectalis paradoxically tightens on strain, refer for anorectal manometry and biofeedback.

Step 3 management: Disimpact manually before initiating an oral regimen — giving osmotic laxatives to an impacted patient causes overflow leakage and abdominal pain, not relief.

General: signs of weight loss, pallor (anemia from occult GI loss), thyroid enlargement, dry skin/bradycardia (hypothyroidism), parkinsonian features.

Abdominal exam:

Mandatory digital rectal exam (DRE) — high-yield and frequently tested:

Normal: perineal descent 1–3.5 cm, relaxation of puborectalis (palpable posterior release), opening of anal canal

Dyssynergia: paradoxical contraction or failure to relax puborectalis during strain — the cardinal bedside finding of outlet dysfunction

Neurologic screen: perianal sensation, anal wink reflex (S2–S4), lower extremity strength/reflexes if cord lesion suspected.

Pelvic exam in women: rectocele (anterior rectal wall bulge into vagina on strain), enterocele, uterine prolapse — structural contributors to outlet dysfunction.

Diagnostic Workup — Initial Labs and Screening

— CBC — anemia raises concern for CRC, IBD, or chronic blood loss

— TSH — hypothyroidism; low threshold to check in women and elderly

— Serum calcium — hypercalcemia (hyperparathyroidism, malignancy)

— Glucose/HbA1c — diabetic autonomic neuropathy

— BMP — hypokalemia, hypomagnesemia, CKD

— Routine celiac serology, cortisol, and heavy metals are not recommended without specific indication

— Abdominal radiograph (KUB): useful only when impaction, obstruction, or megacolon suspected; not for routine quantification of stool burden in adults

— CT abdomen/pelvis: reserved for suspected obstruction, mass, or complication

— Age ≥45 due for CRC screening (USPSTF 2021)

— Any alarm feature: hematochezia, IDA, weight loss, family history of CRC or IBD, new-onset after 50, change in stool caliber

— Failure to respond to appropriate empiric therapy in older patients

Key distinction: Routine colonoscopy is NOT indicated for chronic constipation alone in a patient <45 with no alarm features. This is a frequent Step 3 distractor — ordering colonoscopy "to evaluate constipation" in a 32-year-old healthy woman is the wrong answer; start empiric therapy.

Board pearl: Combine constipation evaluation with age-appropriate CRC screening — if a 55-year-old has never had a colonoscopy and presents with new constipation, colonoscopy serves both purposes and is the highest-yield single test.

Step 3 management: Document alarm features explicitly in the chart — their absence justifies empiric therapy and protects against later allegations of missed CRC.

Most young, otherwise healthy patients with chronic constipation and no alarm features need NO testing — empiric trial of fiber + osmotic laxative is appropriate first-line.

Targeted labs when secondary cause suspected or in older adults:

Imaging — limited role in initial outpatient workup:

Colonoscopy indications in the constipation workup:

Stool studies: FIT/FOBT is screening, not diagnostic for constipation; consider if anemia or occult blood concerns.

Advanced and Confirmatory Studies

— First-line advanced test in refractory cases

— Measures resting/squeeze pressures, rectoanal inhibitory reflex (absent → Hirschsprung), and dynamics during simulated defecation

— Balloon expulsion >1 minute strongly suggests dyssynergic defecation

— Identifies candidates for biofeedback therapy (the definitive treatment for dyssynergia, >70% response)

— Patient swallows 24 radiopaque markers; KUB on day 5

— >5 markers retained scattered throughout colon → slow-transit constipation

— >5 markers clustered in rectosigmoid → outlet dysfunction

— <5 retained → normal transit (functional)

— Evaluates structural outlet problems: rectocele, intussusception, enterocele, excessive perineal descent

— Indicated when manometry is equivocal or surgical pelvic floor pathology suspected

— 1) Anorectal manometry + balloon expulsion → rule out dyssynergia first

— 2) If normal → colonic transit study

— 3) If structural defect suspected → defecography

Board pearl: Always rule out defecatory dysfunction before slow-transit — patients with dyssynergia often fail laxatives and are mistakenly labeled slow-transit. Treating with more osmotics rather than biofeedback is a classic Step 3 wrong-answer trap.

CCS pearl: In a refractory case, advance time by 4 weeks after first-line therapy before ordering manometry; ordering it at the index visit is premature and gets penalized.

Reserved for refractory constipation — failure of an adequate trial (≥4 weeks) of lifestyle modification plus an osmotic laxative — or strong clinical suspicion for specific subtype.

Anorectal manometry with balloon expulsion test:

Colonic transit study (Sitz marker test):

Defecography (MRI or fluoroscopic):

Wireless motility capsule — alternative whole-gut transit assessment.

Order of advanced testing (Step 3 sequencing):

Hirschsprung disease: consider in lifelong severe constipation since infancy; absence of rectoanal inhibitory reflex on manometry → rectal suction biopsy.

First-Line Management Logic and Lifestyle

— Step 1: Education, lifestyle, and soluble fiber

— Step 2: Osmotic laxative (PEG preferred)

— Step 3: Add or substitute stimulant laxative

— Step 4: Secretagogue or prokinetic (lubiprostone, linaclotide, plecanatide, prucalopride)

— Step 5: Anorectal testing → biofeedback if dyssynergia; surgical referral if structural

— Fluid: 1.5–2 L/day; additional water beyond euvolemia does not improve constipation

— Fiber: gradually increase to 25–35 g/day, prefer soluble (psyllium); insoluble fiber (bran) can worsen bloating in slow-transit and IBS-C

— Physical activity: regular aerobic activity improves transit, especially in sedentary elderly

— Toileting habits: attempt BM 15–30 min after meals (gastrocolic reflex), use a footstool to achieve hip flexion (squat position straightens anorectal angle), avoid prolonged straining and phone use

Step 3 management: Before escalating to prescription agents, document a 4-week trial of fiber + PEG with appropriate dosing. Skipping this step is the most common error on management vignettes.

Board pearl: Squatting posture (footstool) is a cheap, evidence-supported intervention frequently shown on outpatient counseling questions — pair it with post-meal toileting timing.

Key distinction: Increasing fiber in patients with slow-transit constipation or opioid-induced constipation often worsens bloating without improving evacuation — go directly to osmotic agents in these subgroups.

Stepwise outpatient framework:

Lifestyle measures (counsel at every visit, modest evidence but low risk):

Medication reconciliation: deprescribe or substitute offenders when feasible — switch verapamil to amlodipine, taper anticholinergics, address opioid use.

Set expectations: improvement typically over 2–4 weeks, not days; warn about transient bloating with fiber initiation.

Pharmacotherapy — First-Line Agents

— Psyllium (soluble, fermentable but well-tolerated): 3–6 g BID, titrate

— Methylcellulose, calcium polycarbophil: less gas

— Avoid in suspected obstruction, megacolon, or severely impaired motility

— Polyethylene glycol 3350 (PEG): 17 g in 8 oz fluid daily; first-line by efficacy and tolerability; safe long-term, including in elderly and pregnancy

— Lactulose: 15–30 mL daily; more bloating/flatulence; preferred when hepatic encephalopathy coexists

— Sorbitol: cheaper lactulose equivalent

— Magnesium hydroxide/citrate: effective but avoid in CKD (hypermagnesemia risk)

— Bisacodyl 5–15 mg PO qHS, or senna 8.6–17.2 mg qHS

— Long-term use is safe; the old teaching of "cathartic colon" has been refuted

— Caution: cramping, electrolyte loss with overuse

— Glycerin suppository (mild), bisacodyl suppository, tap water or saline enema

— Avoid phosphate (Fleet) enemas in elderly and CKD — hyperphosphatemia, AKI, deaths reported

Board pearl: PEG 17 g daily is the single best-supported first-line prescription for chronic constipation across all age groups; choose it over lactulose or magnesium on the test unless a contraindication is given.

Step 3 management: When opioid-induced constipation is the issue, start a stimulant + osmotic prophylactically with the opioid prescription — docusate alone is inadequate and a frequent wrong answer.

Bulk-forming (fiber) agents — first pharmacologic step in functional constipation:

Osmotic laxatives — workhorse of chronic management:

Stimulant laxatives — add if osmotic alone fails, or for rescue:

Suppositories/enemas for outlet dysfunction or acute impaction:

Stool softeners (docusate): limited efficacy; not recommended as monotherapy by ACG.

Second-Line and Specialty Pharmacotherapy

— Lubiprostone (ClC-2 activator) 24 mcg BID with food; FDA-approved for chronic idiopathic constipation (CIC), IBS-C (women), and opioid-induced constipation in chronic non-cancer pain. Nausea is dose-limiting; take with food. Pregnancy: avoid.

— Linaclotide (guanylate cyclase-C agonist) 145 mcg (CIC) or 290 mcg (IBS-C) daily, on empty stomach 30 min before breakfast. Contraindicated in patients <6 years; avoid <18 years. Diarrhea is main AE.

— Plecanatide 3 mg daily; similar mechanism, comparable efficacy, often better tolerated.

— Prucalopride (selective 5-HT4 agonist) 2 mg daily; effective in slow-transit and chronic idiopathic constipation. Renal dose adjustment (1 mg if CrCl <30). Safer cardiac profile than older 5-HT4 agents (tegaserod, cisapride — withdrawn).

— Methylnaltrexone SC or PO

— Naloxegol 25 mg daily PO (avoid strong CYP3A4 inhibitors)

— Naldemedine 0.2 mg daily PO

— Do not cross BBB → preserve analgesia; contraindicated in suspected GI obstruction (perforation risk)

Board pearl: For OIC, the correct escalation sequence is: stimulant + osmotic → switch/add PAMORA. Avoid lubiprostone if a PAMORA option is available; never give a PAMORA if obstruction is suspected.

Key distinction: Linaclotide is contraindicated in pediatric patients <6, with safety data lacking up to 18 — a tested fact.

Indicated when ≥4 weeks of optimized PEG ± stimulant fails, or for specific subtypes.

Secretagogues (intestinal chloride/fluid secretion):

Prokinetic:

Opioid-induced constipation (OIC) — when laxatives fail, use peripherally acting mu-opioid receptor antagonists (PAMORAs):

Biofeedback therapy — first-line for dyssynergic defecation; superior to laxatives in this subgroup, >70% sustained response.

Surgery — last resort: subtotal colectomy with ileorectal anastomosis for severe medically refractory slow-transit (with normal anorectal function confirmed), or repair of symptomatic rectocele/rectal prolapse.

Special Populations — Elderly, Renal, and Hepatic Impairment

— Multifactorial: immobility, polypharmacy, reduced fluid intake, comorbid neuro/endocrine disease, dementia, decreased rectal sensation

— Higher risk of fecal impaction with overflow incontinence — often misdiagnosed as diarrhea

— Stercoral colitis/perforation is a rare but lethal complication of chronic impaction in elderly

— Screen for depression and cognitive impairment as contributors

— Preferred agents: PEG 3350 (safe, well-tolerated, no electrolyte shifts); senna for stimulant rescue

— Avoid: magnesium products (CKD/hypermagnesemia), phosphate (Fleet) enemas (hyperphosphatemia, AKI, deaths reported), mineral oil (aspiration pneumonia), bulk fiber in bedbound or low-fluid patients (impaction risk)

— Avoid magnesium- and phosphate-containing laxatives/enemas

— PEG is safe (not absorbed)

— Linaclotide, lubiprostone, plecanatide: no significant renal adjustment

— Prucalopride: reduce to 1 mg daily if CrCl <30

— Naloxegol: 12.5 mg daily if CrCl <60

— Lactulose preferred if coexisting hepatic encephalopathy (titrate to 2–3 soft stools/day)

— Lubiprostone: reduce dose in moderate–severe hepatic impairment

— Naloxegol: avoid in severe hepatic impairment

Board pearl: In an elderly patient with "diarrhea" and a hard rectal mass on DRE, the diagnosis is fecal impaction with overflow incontinence — disimpact manually, then start scheduled PEG; do not prescribe loperamide.

Step 3 management: Avoid phosphate enemas in patients >65 or with CKD — choose tap water or mineral oil enema instead. This appears on geriatric prescribing safety questions.

Elderly outpatients (constipation in >30% of community-dwelling adults >65):

Chronic kidney disease:

Hepatic impairment:

Polypharmacy review at every visit — anticholinergic burden scales (Beers Criteria) identify high-risk drugs (oxybutynin, diphenhydramine, TCAs).

Special Populations — Pregnancy and Pediatrics

— Affects up to 40%; mechanisms include progesterone-mediated decreased motility, mechanical compression, iron supplementation, decreased activity

— Lifestyle first: fiber 25–30 g/day, hydration, activity

— Safe pharmacologic options (Step 3 favorites):

— Avoid:

— Most common cause: functional constipation with stool-withholding behavior, often triggered by toilet training, school avoidance, or painful BM

— Red flags warranting workup: delayed meconium passage >48 h (Hirschsprung), failure to thrive, abdominal distention, anal stenosis, abnormal neuro exam, tight empty rectum on DRE

— Treatment:

— Avoid stimulant laxatives chronically in young children unless specialist-directed.

Board pearl: PEG 3350 is first-line for functional constipation in both pregnancy and pediatrics — high efficacy, low absorption, excellent safety record.

Key distinction: Delayed meconium >48 h + failure to thrive + tight rectum → Hirschsprung, not functional constipation. Refer for rectal biopsy.

Pregnancy:

Psyllium and other bulk fibers — first-line, minimally absorbed

PEG 3350 — safe; preferred osmotic agent in pregnancy

Lactulose — safe; more flatulence

Docusate — safe but limited efficacy

Bisacodyl, senna — short-term use acceptable

Mineral oil (impairs fat-soluble vitamin absorption, neonatal coagulopathy)

Castor oil (uterine stimulation)

Magnesium sulfate chronically (electrolyte disturbance)

Lubiprostone, linaclotide, plecanatide, prucalopride — insufficient safety data; avoid

Postpartum: hemorrhoids, episiotomy/perineal trauma → fear of defecation; use stool softeners + PEG; ensure adequate analgesia.

Pediatric outpatient constipation:

Disimpaction first: PEG 1–1.5 g/kg/day × 3–6 days, or enema

Maintenance: PEG 3350 0.4–0.8 g/kg/day, titrate to 1–2 soft BMs/day; continue at least 2 months and 1 month beyond resolution of symptoms

Behavioral: scheduled toilet sits after meals, reward systems, demystification

Complications and Adverse Outcomes

— Most common in elderly, bedbound, opioid users, neurogenic bowel

— Presents with abdominal pain, nausea, paradoxical overflow diarrhea/incontinence, urinary retention

— Management: manual disimpaction first, then enemas (tap water or mineral oil; avoid phosphate in elderly/CKD), followed by oral PEG maintenance

— Pressure necrosis of colonic wall from hard fecaloma, typically sigmoid

— High mortality; presents as peritonitis in chronically constipated elderly

— CT shows fecaloma with adjacent wall thickening, pericolonic stranding, free air if perforated

— Surgical emergency

— From chronic straining and hard stools

— Treat the constipation (fiber + PEG) plus topical care; sitz baths, topical nifedipine or nitroglycerin for fissures

— Chronic straining → pudendal neuropathy, descending perineum syndrome

— Risk factor: chronic constipation with redundant elongated sigmoid (institutionalized elderly, neurologic disease)

— Plain film: "coffee bean" sign; treat with endoscopic detorsion then elective sigmoidectomy

— Stimulant abuse: hypokalemia, metabolic alkalosis

— Phosphate enemas: hyperphosphatemia, hypocalcemia, AKI

Board pearl: Sudden, severe abdominal pain with peritoneal signs in a chronically constipated elderly patient → suspect stercoral perforation; get urgent CT and surgical consult — do not give another enema.

Step 3 management: Overflow incontinence is often missed — when an elderly nursing home patient is reported to have "diarrhea," DRE first to exclude impaction before ordering C. diff testing.

Fecal impaction:

Stercoral colitis and stercoral perforation:

Hemorrhoids and anal fissures:

Rectal prolapse and pelvic floor dysfunction:

Sigmoid volvulus:

Urinary retention and UTIs from rectal mass effect, especially in elderly

Electrolyte abnormalities and dehydration from chronic laxative overuse:

Psychosocial impact: significant QoL impairment, anxiety around defecation, social withdrawal in elderly.

When to Escalate Care — Referral, Specialist, and Admission

— Gastroenterology:

— Colorectal surgery: symptomatic rectocele, full-thickness rectal prolapse, refractory slow-transit being considered for subtotal colectomy

— Pelvic floor physical therapy / biofeedback: dyssynergic defecation (first-line treatment), not for primary slow-transit

— Urogynecology: women with pelvic organ prolapse contributing to outlet dysfunction

— Neurology: suspected MS, Parkinson, spinal cord pathology

— Endocrinology: refractory hypothyroidism, hypercalcemia from hyperparathyroidism

— Suspected bowel obstruction (vomiting, distention, no flatus, peritoneal signs)

— Acute severe abdominal pain — concern for stercoral perforation, sigmoid volvulus, ischemia

— Fecal impaction unable to be managed in clinic

— Significant rectal bleeding with hemodynamic concern

— Bowel obstruction or perforation

— Severe impaction requiring inpatient bowel regimen + monitoring

— Severe electrolyte derangements from laxative misuse

— Failure of outpatient disimpaction in frail elderly

CCS pearl: On a CCS case of inpatient constipation, the correct sequence is: NPO if obstruction suspected → KUB or CT → manual disimpaction or enema → resume PO intake → schedule PEG maintenance → reconcile medications before discharge. Skipping medication reconciliation costs points.

Step 3 management: Document trial duration, dose, adherence, and reason for failure before each escalation; insurers and Step 3 stems both expect stepwise justification.

Outpatient referrals:

Failure of optimized first- and second-line therapy after 8–12 weeks

Suspected dyssynergic defecation or slow-transit requiring anorectal manometry, transit studies, defecography

Alarm features warranting colonoscopy

Consideration of secretagogues, prucalopride, or PAMORAs when primary care is uncomfortable

Same-day or ED evaluation:

Admission criteria:

Key Differentials — Other GI Causes

— Rome IV: recurrent abdominal pain ≥1 day/week × 3 months, related to defecation, with change in stool frequency or form

— Distinction from CIC: pain is the defining feature of IBS-C

— Treatment overlaps (PEG, linaclotide, plecanatide); avoid lubiprostone in men (only approved for women with IBS-C)

— New-onset constipation in patient ≥45, change in stool caliber ("pencil-thin"), hematochezia, IDA, weight loss, family history

— Colonoscopy mandatory

— Strictures from ischemic colitis, diverticulitis, IBD, anastomotic stenosis, radiation

— Volvulus (sigmoid in elderly, cecal in younger)

— Hernias with incarceration

— Crohn strictures cause obstructive constipation; rarely UC unless proctitis with overflow-type symptoms

— Chronic constipation is both cause and consequence; treat with fiber + PEG

— Anal fissure, hemorrhoids, perianal abscess → pain-mediated avoidance of defecation

— Rectal prolapse, rectocele, intussusception

— Hirschsprung (congenital, lifelong), Chagas disease (immigrant from Latin America), idiopathic

— Distinguish on manometry (absent rectoanal inhibitory reflex in Hirschsprung)

Key distinction: IBS-C requires recurrent pain related to defecation; CIC does not. Mislabeling pain-free constipation as IBS misses appropriate algorithm.

Board pearl: A 60-year-old with new constipation, 10-lb weight loss, and microcytic anemia is colorectal cancer until proven otherwise — colonoscopy is the answer, not a laxative trial.

Irritable bowel syndrome with constipation (IBS-C):

Colorectal cancer:

Mechanical obstruction (non-malignant):

Inflammatory bowel disease:

Diverticular disease:

Anorectal pathology:

Megacolon/megarectum:

Celiac disease: more commonly diarrhea but can present with constipation; consider in refractory cases with other features (anemia, weight loss).

Key Differentials — Non-GI Causes

— Hypothyroidism — slowed motility; check TSH in any new chronic constipation in older adults or women

— Diabetes mellitus — autonomic neuropathy, often with gastroparesis

— Hypercalcemia — hyperparathyroidism, malignancy, vitamin D toxicity

— Hypokalemia, hypomagnesemia — impaired smooth muscle function

— Pheochromocytoma (rare) — episodic constipation with HTN, palpitations

— Pregnancy — progesterone effect (see Chunk 10)

— Parkinson disease — constipation often precedes motor symptoms by years; tested association

— Multiple sclerosis — both constipation and incontinence

— Spinal cord lesions/injury — variable patterns; reflex bowel above conus, areflexic below

— Stroke, autonomic neuropathy, cerebral palsy, dementia

— Opioids — μ-receptor activation in myenteric plexus

— Anticholinergics — TCAs (amitriptyline), antihistamines (diphenhydramine), oxybutynin, antipsychotics (clozapine, olanzapine)

— Calcium channel blockers — especially verapamil

— Iron supplements, calcium supplements (especially CaCO3), aluminum-containing antacids

— 5-HT3 antagonists — ondansetron, granisetron

— Clonidine, antihypertensives

— NSAIDs, sucralfate, bismuth, cholestyramine

— Vinca alkaloid chemotherapy (vincristine — autonomic neuropathy)

— Depression (and its anticholinergic treatments)

— Eating disorders (anorexia nervosa) — slow transit from caloric restriction, laxative abuse cycles

— Systemic sclerosis — both upper (GERD, dysmotility) and lower GI dysmotility

— Amyloidosis

— Lead toxicity — colicky abdominal pain with constipation

Board pearl: New chronic constipation in a middle-aged man with subtle bradykinesia or REM sleep behavior disorder → think prodromal Parkinson disease; constipation can predate motor symptoms by a decade.

Key distinction: Always check TSH, calcium, glucose, and potassium in older adults with new constipation — these four reversible causes are repeatedly tested.

Endocrine and metabolic:

Neurologic:

Medications (single most common reversible cause):

Psychiatric:

Connective tissue/systemic:

Long-Term Plan and Secondary Prevention

— Continue PEG 3350 daily indefinitely if effective; safe long-term across decades

— Stimulants (senna, bisacodyl) safe for daily/scheduled use — the "tolerance" and "cathartic colon" concerns have been disproven

— Re-evaluate dosing every 3–6 months; titrate to 1 soft BM/day (Bristol 3–4)

— Periodic deprescribing trials appropriate for younger patients with reversed lifestyle factors

— Fiber goal 25–35 g/day from diet preferentially; supplements as adjunct

— Adequate hydration to euvolemia

— Daily physical activity, especially in elderly

— Scheduled toileting post-meals; footstool

— Co-prescribe stimulant + osmotic with any opioid >7 days

— Reassess opioid need at every visit per CDC chronic pain guidelines

— Consider PAMORA when laxatives inadequate

— Confirm colonoscopy or equivalent CRC screening per USPSTF (age 45–75) — chronic constipation visits are good "catch-up" opportunities

— Bowel diary, recognition of overflow incontinence vs. true diarrhea

— When to call: no BM >5 days, severe pain, vomiting, rectal bleeding, weight loss

— Avoid laxative misuse, especially in adolescents with disordered eating

Board pearl: Daily PEG is safe long-term — reassure patients (and answer correctly on the test) that chronic use does not cause dependence, electrolyte derangement, or colonic damage.

Step 3 management: Use the constipation visit as a value-based care touchpoint: reconcile meds, confirm CRC screening, review immunizations and depression screening (PHQ-2).

Maintenance pharmacotherapy — most patients with chronic functional constipation require ongoing therapy:

Lifestyle reinforcement at every visit:

Medication reconciliation at each visit — opportunistic deprescribing of anticholinergics, switching verapamil to amlodipine, optimizing opioid stewardship.

Opioid stewardship in chronic pain:

Cancer screening alignment:

Patient education and self-management:

Pelvic floor maintenance post-biofeedback: home exercises, occasional booster sessions.

Follow-Up, Monitoring, and Counseling

— Initial therapy review at 4 weeks to assess response, adherence, side effects

— If effective: every 3–6 months for routine maintenance and medication reconciliation

— If refractory at 4 weeks: optimize dose, add stimulant, then reassess at 8 weeks; if still refractory → anorectal manometry referral

— ≥3 spontaneous BMs/week

— Bristol 3–4 stool form

— Reduced straining and sense of complete evacuation

— Improvement on validated tools (PAC-SYM, PAC-QOL) for refractory cases

— Electrolytes if on chronic stimulants or magnesium products, especially in CKD/elderly

— TSH annually if hypothyroidism is a known contributor

— Renal function if on naloxegol or prucalopride

— Watch for diarrhea/dehydration with linaclotide/plecanatide

— Bowel habit normalization (no "right" frequency — 3/week to 3/day is normal)

— Footstool and post-meal toileting

— Avoid suppressing the urge to defecate

— Recognize and report alarm features (bleeding, weight loss, new severe pain)

— Address laxative misuse anxiety; reassure regarding long-term PEG safety

Step 3 management: Schedule the 4-week check at the index visit — it's the inflection point for escalation and a frequent vignette anchor.

Board pearl: "Normal" BM frequency ranges from 3 per week to 3 per day; reassure patients with daily BMs that they are not constipated simply because they perceive "incomplete" emptying — symptoms, not frequency alone, drive diagnosis.

Follow-up cadence:

Response metrics — define success with the patient:

Monitoring parameters:

Counseling points at each visit:

Pelvic floor rehabilitation (biofeedback): typically 4–6 weekly sessions; outcomes durable at 2 years in >70% of dyssynergia patients.

Shared decision-making about advancing to secretagogues, prucalopride, or surgical evaluation — include cost, side-effect profile, and patient priorities.

Ethical, Legal, and Patient Safety Considerations

— Long-term laxative use: counsel that daily PEG and stimulants are safe — patients often refuse based on outdated "addiction" beliefs; document the discussion

— Biofeedback referral: requires patient buy-in; sensitive given involvement of perineal exam and physical therapy; offer same-gender clinician when possible

— Off-label use: lubiprostone in men with IBS-C, prucalopride in pregnancy — explicitly discuss

— Pediatric severe constipation with failure to thrive — assess for neglect; mandated reporting if suspected

— Adolescent with laxative misuse + weight loss — screen for eating disorder; involve mental health and parents per state law

— Elder neglect: chronic untreated constipation, impaction, dehydration in dependent adults — report to Adult Protective Services where laws apply

— Sexual abuse history is overrepresented in dyssynergic defecation; trauma-informed approach essential

— Hospital discharge: opioid prescriptions without concurrent bowel regimen are a recognized patient safety failure; always co-prescribe a stimulant + osmotic at discharge for any new opioid

— Nursing home transfers: ensure bowel regimen orders accompany the patient; absence is a common adverse event leading to impaction

— Surgical patients: postoperative ileus vs. opioid-induced constipation must be distinguished before laxative initiation

— Avoid anticholinergics, mineral oil, and phosphate enemas in elderly per Beers

— Fiber-rich diets and probiotics may be cost-prohibitive; PEG is generic, low-cost, and covered by most formularies — prefer it for equitable access

— Avoid unnecessary KUBs, colonoscopies, and CT scans in young patients without alarm features — Choosing Wisely

Board pearl: Co-prescribing a bowel regimen with every new opioid prescription is a Step 3 patient-safety expectation; failure to do so is the wrong answer on transitions-of-care vignettes.

Step 3 management: Document alarm-feature absence and shared decision-making for empiric therapy; this protects against missed-diagnosis liability.

Informed consent and shared decision-making:

Mandatory reporting and safeguarding:

Transition-of-care safety:

Polypharmacy and Beers Criteria:

Health equity:

Diagnostic stewardship:

High-Yield Associations and Rapid-Fire Facts

Board pearl: When the vignette gives a young patient with no red flags, the answer is almost always lifestyle + PEG, not colonoscopy and not advanced testing.

Rome IV — clinical diagnosis of functional constipation; no testing required without alarm features

PEG 3350 17 g daily — best evidence, all ages, pregnancy-safe

Docusate — ineffective monotherapy; deprescribe

Daily PEG is safe long-term — no cathartic colon

Phosphate (Fleet) enemas — avoid in elderly and CKD (hyperphosphatemia, AKI, death)

Mineral oil — aspiration pneumonia risk in elderly; neonatal coagulopathy in pregnancy

Verapamil — most constipating CCB; switch to amlodipine

Opioids — co-prescribe stimulant + osmotic; PAMORA if refractory

PAMORAs contraindicated in suspected obstruction — perforation risk

Lubiprostone — nausea, take with food; CIC, IBS-C in women, OIC in chronic non-cancer pain

Linaclotide — empty stomach, contraindicated <6 years, avoid <18

Prucalopride — selective 5-HT4 agonist, safe cardiac profile (unlike withdrawn tegaserod/cisapride); renal dose adjustment

Dyssynergic defecation — paradoxical puborectalis contraction on DRE strain; biofeedback is first-line, >70% response

Slow-transit constipation — Sitz markers scattered throughout colon at day 5; subtotal colectomy is last resort (with normal anorectal function)

Hirschsprung — absent rectoanal inhibitory reflex; rectal suction biopsy diagnostic

Chagas — megacolon in Latin American immigrant

Parkinson — constipation can precede motor symptoms by years

Hypothyroidism, hypercalcemia, hypokalemia, DM — four metabolic causes to screen

Sigmoid volvulus — "coffee bean" sign; endoscopic detorsion then elective sigmoidectomy

Stercoral perforation — chronic impaction → necrosis; surgical emergency

Overflow incontinence — looks like diarrhea; DRE first before loperamide or C. diff testing

Footstool + post-meal toileting — cheap, effective, frequently tested

CRC screening — colonoscopy required in new constipation with alarm features or age ≥45 unscreened

IBS-C vs. CIC — pain related to defecation defines IBS-C

Beers Criteria — anticholinergics, mineral oil, phosphate enemas: avoid in elderly

Board Question Stem Patterns

— 28-year-old woman, 6 months of hard, infrequent stools, normal exam, no alarm features → Answer: increase fiber and start PEG 3350 daily. Distractors: colonoscopy, CT abdomen, anorectal manometry.

— 62-year-old with new constipation, 12-lb weight loss, microcytic anemia → Answer: colonoscopy. Distractors: empiric PEG, CT, TSH alone.

— Patient failed 6 weeks of PEG and bisacodyl → Answer: anorectal manometry with balloon expulsion to evaluate for dyssynergia before colonic transit study.

— Strain → paradoxical anal tightening on DRE; manometry confirms → Answer: biofeedback therapy. Distractor: linaclotide, surgery.

— Liquid stool leaking, abdominal distention → Answer: DRE → manual disimpaction. Distractor: loperamide, C. diff testing, IV fluids alone.

— Cancer pain patient on morphine, constipated despite docusate → Answer: add senna + PEG, escalate to methylnaltrexone or naloxegol if refractory. Distractor: stop opioids, lubiprostone alone.

— 78-year-old with CKD needs disimpaction → Answer: tap water or mineral oil enema, NOT phosphate (Fleet).

— Third-trimester constipation → Answer: fiber + PEG. Distractors: castor oil, mineral oil, linaclotide.

— Newborn delayed meconium + tight empty rectum → Answer: rectal suction biopsy; manometry shows absent RAIR.

— Chronic constipation, sudden severe abdominal pain, peritonitis, free air on CT → Answer: surgical consult, NOT another enema.

— Chronic constipation + subtle rest tremor or hyposmia → consider prodromal Parkinson.

— New constipation after starting verapamil → Answer: switch to amlodipine.

Board pearl: When alarm features appear in the stem, the right answer is almost always a diagnostic test (most often colonoscopy), not a therapeutic trial.

Pattern 1 — "Empiric therapy in young healthy patient":

Pattern 2 — "Alarm features in older adult":

Pattern 3 — "Refractory constipation":

Pattern 4 — "Dyssynergic defecation":

Pattern 5 — "Elderly nursing home patient with diarrhea":

Pattern 6 — "Opioid-induced constipation":

Pattern 7 — "Avoid this enema":

Pattern 8 — "Pregnancy":

Pattern 9 — "Hirschsprung":

Pattern 10 — "Stercoral perforation":

Pattern 11 — "Hidden Parkinson":

Pattern 12 — "Medication culprit":

One-Line Recap

Chronic constipation is a clinical Rome IV diagnosis treated empirically with lifestyle changes and PEG 3350 in patients without alarm features, while red flags, refractory symptoms, and suspected outlet dysfunction drive a stepwise workup of labs, colonoscopy, anorectal manometry with biofeedback, and colonic transit studies.

Board pearl: When in doubt on Step 3 — young + no red flags = PEG and lifestyle; older + red flags = colonoscopy; refractory = manometry before more drugs.

First move: rule out alarm features (age ≥45 unscreened, bleeding, weight loss, IDA, family history, sudden change in caliber) and reconcile medications (opioids, anticholinergics, verapamil, iron, ondansetron); screen TSH, calcium, glucose, potassium when secondary cause suspected.

First-line therapy: fiber 25–35 g/day (psyllium preferred) + PEG 3350 17 g daily; add senna or bisacodyl if needed; reserve lubiprostone, linaclotide, plecanatide, and prucalopride for refractory chronic idiopathic constipation; use PAMORAs (naloxegol, methylnaltrexone, naldemedine) for refractory opioid-induced constipation — never with suspected obstruction.

Don't miss dyssynergic defecation: paradoxical puborectalis tightening on DRE strain → anorectal manometry with balloon expulsion → biofeedback (first-line treatment, >70% durable response); biofeedback beats more laxatives.

Safety anchors: avoid phosphate enemas and mineral oil in elderly/CKD; co-prescribe a bowel regimen with every new opioid; perform DRE before treating "diarrhea" in elderly to exclude overflow incontinence from impaction; recognize stercoral perforation as a surgical emergency; use the constipation visit to catch up CRC screening and deprescribe high anticholinergic burden.