Constipation

Introduction

Constipation is a functional or organic disorder of bowel habit, affecting ~15–20% of the general population. It is more common in women, the elderly, and those with sedentary lifestyles or chronic diseases.

It is not a disease but a symptom complex — ranging from simple lifestyle-related constipation to serious conditions such as bowel obstruction or colorectal cancer.

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Normal Bowel Function

• Normal range: 3 bowel movements/day → 3/week.

• Transit time: food → stool passage = ~24–72 hours.

• Influenced by diet, fluid intake, physical activity, hormones, medications.

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Types of Constipation

1. Primary (functional):

   • Normal-transit constipation: perception of constipation despite normal colonic transit.

   • Slow-transit constipation: delayed movement of stool through colon.

   • Defecatory disorder: impaired rectal evacuation due to pelvic floor dysfunction.

2. Secondary (organic):

   • Due to systemic disease, medications, or structural abnormalities.

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Causes of Constipation

1. Lifestyle & Dietary

• Low fiber intake.

• Inadequate fluid intake.

• Sedentary lifestyle.

• Suppressing urge to defecate.

2. Medications

• Opioids (morphine, codeine).

• Anticholinergics (oxybutynin, amitriptyline).

• Iron supplements.

• Calcium channel blockers (verapamil).

• Antacids with calcium/aluminum.

• Antihistamines, anticonvulsants.

3. Gastrointestinal & Structural

• Colorectal cancer.

• Strictures, diverticulosis.

• Rectocele, anal fissures, hemorrhoids (painful defecation).

4. Neurological

• Parkinson’s disease.

• Multiple sclerosis.

• Spinal cord lesions.

• Stroke.

5. Metabolic/Endocrine

• Hypothyroidism.

• Diabetes mellitus (autonomic neuropathy).

• Hypercalcemia.

• Hypokalemia.

6. Psychological

• Depression, anxiety, eating disorders.

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Clinical Features

• Infrequent stools (<3/week).

• Hard, lumpy stools (Bristol Stool Chart type 1–2).

• Straining, sense of incomplete evacuation.

• Abdominal bloating, discomfort.

• Rectal pain, anal fissures (secondary).

• Alarm features:

  • Rectal bleeding.

  • Weight loss.

  • Iron-deficiency anemia.

  • Family history of colorectal cancer.

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Diagnostic Approach

1. History

• Onset, duration, stool frequency/consistency.

• Diet, fluid intake, activity level.

• Medication history.

• Associated symptoms (pain, blood, weight loss).

2. Examination

• Abdominal exam: distension, masses.

• Digital rectal exam: fissures, hemorrhoids, masses, rectocele, sphincter tone.

3. Investigations

• Basic labs: CBC, thyroid function, calcium, glucose, electrolytes.

• Colonoscopy/sigmoidoscopy: If alarm symptoms or age >50.

• Imaging (barium enema, CT colonography): Suspected obstruction.

• Transit studies (radio-opaque markers): Slow transit constipation.

• Anorectal manometry, balloon expulsion test: Defecatory disorders.

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Management and Treatment

Principle: Relieve symptoms, prevent complications, address underlying cause.

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A. Lifestyle & Dietary Measures (First-line)

• Increase dietary fiber (20–30 g/day): fruits, vegetables, whole grains.

• Ensure adequate hydration (1.5–2 L water/day).

• Regular exercise.

• Establish regular bowel habits, avoid suppressing urge.

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B. Pharmacological Treatment

1. Bulk-Forming Laxatives

• Absorb water, increase stool bulk.

• Psyllium husk: 3.4 g orally in 240 mL water, 1–3 times daily.

• Methylcellulose: 2 g orally once or twice daily.

2. Osmotic Laxatives

• Draw water into bowel.

• Lactulose: 15–30 mL orally daily; titrate to effect.

• Polyethylene glycol (PEG): 17 g powder dissolved in water once daily.

• Magnesium hydroxide: 30–60 mL orally at bedtime (avoid in renal failure).

3. Stimulant Laxatives

• Stimulate intestinal motility.

• Bisacodyl: 5–10 mg orally at bedtime or 10 mg suppository PR.

• Senna: 15–30 mg orally at bedtime.

• Use short-term to avoid dependence.

4. Stool Softeners (Emollients)

• Facilitate stool passage.

• Docusate sodium: 100 mg orally once or twice daily.

5. Lubricants

• Mineral oil: 15–45 mL orally daily (not for long-term use, risk of aspiration).

6. Prosecretory/Prokinetic Agents (for chronic refractory constipation)

• Lubiprostone: 24 mcg orally twice daily with food.

• Linaclotide: 145–290 mcg orally once daily on empty stomach.

• Prucalopride (5-HT4 agonist): 2 mg orally once daily.

7. Opioid-Induced Constipation (OIC)

• Naloxegol: 25 mg orally once daily.

• Methylnaltrexone: 12 mg SC every other day.

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C. Treating Underlying Causes

• Hypothyroidism: Levothyroxine 25–100 mcg orally daily (titrated).

• Diabetes: Optimize glycemic control.

• Depression: Adjust antidepressants if contributing.

• Obstruction/malignancy: Surgical or oncological treatment.

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D. Non-Pharmacological / Procedural

• Biofeedback therapy: For pelvic floor dysfunction.

• Manual disimpaction: If fecal impaction present.

• Enemas (sodium phosphate, glycerin): For acute relief.

• Surgery: Rare; for refractory severe slow-transit constipation or obstruction.

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Complications

• Hemorrhoids.

• Anal fissures.

• Fecal impaction.

• Rectal prolapse.

• Overflow incontinence.

• Secondary megacolon.

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Prognosis

• Functional constipation: Excellent with lifestyle and laxatives.

• Secondary constipation: Prognosis depends on treating underlying disease (thyroid, cancer, neurological).

• Chronic severe constipation: May require advanced therapies, but quality of life can improve with tailored management.

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Patient Education

• Fiber-rich diet and hydration are key.

• Avoid excessive long-term stimulant laxative use (dependence risk).

• Respond promptly to the urge to defecate.

• Regular physical activity helps bowel motility.

• Report alarm symptoms (blood in stool, unexplained weight loss, severe pain, new onset in elderly).