Constipation and faecal impaction in the elderly

Definition (Rome IV). Two or more of — straining, lumpy or hard stools, sensation of incomplete evacuation, sensation of anorectal obstruction, need for manual manoeuvres, and fewer than three spontaneous bowel movements per week — present for 3 months with onset at least 6 months earlier.

Prevalence. Affects 30–40% of community-dwelling elderly and more than 50% of nursing home residents; laxative use is even more common than the symptom itself.

Age-related mechanisms. Reduced fibre and fluid intake, immobility, reduced rectal sensation and compliance, and impaired pelvic floor and anal sphincter function. Colonic transit itself is largely preserved in healthy ageing — constipation is not a normal part of ageing.

Classification. Primary — normal-transit, slow-transit, and defecatory (dyssynergic) disorder. Secondary — drug-induced, metabolic, neurological or obstructive.

Drug causes (very high yield). Opioids, anticholinergics, tricyclic antidepressants, calcium channel blockers (verapamil), oral iron, calcium and aluminium antacids, diuretics, antiparkinsonian drugs, ondansetron and clozapine.

Secondary causes to exclude. Hypothyroidism, hypercalcaemia, hypokalaemia, diabetes, dehydration, Parkinson's disease, stroke, spinal cord lesions, depression, colorectal carcinoma and strictures.

Assessment. History with the Bristol Stool Chart, full drug review, abdominal examination, and a digital rectal examination in every patient (to detect impaction, tone, masses and dyssynergia). Alarm features — weight loss, bleeding, anaemia, recent change in bowel habit — require colonoscopy. Refractory cases need anorectal manometry and balloon expulsion testing.

Faecal impaction — clinical features. A hard faecal mass in the rectum (or higher in the colon), overflow (paradoxical) diarrhoea and faecal incontinence, abdominal pain, anorexia, urinary retention and delirium. Complications include stercoral ulceration and perforation, bleeding, sepsis and sigmoid volvulus.

Management of impaction. Manual disimpaction with adequate analgesia for a low, hard impaction, followed by a phosphate or arachis oil retention enema. High impaction is treated with high-dose oral polyethylene glycol (macrogol) — contraindicated if obstruction is suspected. Follow with maintenance laxatives and bowel retraining to prevent recurrence.

Stepwise treatment of constipation. Mobility, fluids, gradual fibre increase (avoid bulking agents in immobile, impacted or opioid-treated patients), and toileting after meals to use the gastrocolic reflex → osmotic laxative — polyethylene glycol is first-line (better evidence than lactulose) → stimulant (senna, bisacodyl) → secretagogues (lubiprostone, linaclotide) or the prokinetic prucalopride → PAMORAs (methylnaltrexone, naloxegol, naldemedine) for opioid-induced constipation. Biofeedback is the treatment of choice for dyssynergic defecation. Avoid magnesium salts in CKD; docusate is ineffective.

AGA/ACG joint clinical guideline 2023 on chronic idiopathic constipation — strong recommendation for polyethylene glycol and senna; conditional recommendations for linaclotide, plecanatide, prucalopride and lubiprostone; and a recommendation against routine use of docusate and other stool softeners, which are ineffective.

WGO Global Guideline on Constipation 2025 and the ASCRS 2024 guideline reaffirm the Rome IV framework, recommend early anorectal physiology testing in refractory cases rather than escalating laxatives blindly, and confirm that bulk-forming laxatives must be avoided in opioid-induced constipation because of the risk of impaction and obstruction. Cross-reference: The Bristol Stool Chart and the mode of action of each laxative class are set out in Question 6.