What are appropriate management steps for constipation?

Management of Constipation

Start with lifestyle modifications (increased fluid intake to at least 2 liters daily, regular toileting 30 minutes after meals twice daily, and dietary fiber to 20-25 grams daily), then escalate to polyethylene glycol (PEG) 17g once daily if symptoms persist beyond 2-4 days. 1, 2, 3

Initial Assessment

Before treating constipation, perform a focused evaluation to exclude serious pathology and identify reversible causes:

• Digital rectal examination to rule out fecal impaction, assess sphincter tone, and evaluate for pelvic floor dysfunction during simulated defecation 1
• Check for alarm symptoms: rectal bleeding, unintentional weight loss, sudden change in bowel habits, or severe abdominal pain that could indicate obstruction or malignancy 1, 3
• Review all medications to identify and discontinue constipating agents (anticholinergics, opioids, calcium channel blockers, antacids) when medically appropriate 1, 2
• Complete blood count only unless other symptoms warrant metabolic testing; routine thyroid, calcium, and glucose testing is not recommended for uncomplicated constipation 1

First-Line: Lifestyle Modifications

Implement these measures simultaneously as they work synergistically:

• Optimize toileting habits: Attempt defecation twice daily, 30 minutes after meals to leverage the gastrocolic reflex, limiting straining to ≤5 minutes per attempt 4, 3
• Increase fluid intake to at least 2 liters daily, which is essential before emphasizing fiber supplementation 1, 3
• Increase dietary fiber to 20-25 grams daily through whole grains, vegetables, and fruits 1, 3
• Encourage regular physical activity within the patient's capabilities 1, 3

Critical caveat: Do not recommend fiber supplementation if the patient has low fluid intake or decreased mobility, as this increases risk of mechanical obstruction 4

Second-Line: Pharmacologic Therapy

If lifestyle modifications fail after 2-4 days, escalate to pharmacologic treatment:

First-Line Laxative

Polyethylene glycol (PEG) 17g mixed in 8 oz water once or twice daily is the preferred initial pharmacologic agent because it is the safest option with minimal risk of electrolyte disturbances or dependency 2, 5, 6

• PEG softens stool by retaining water in the bowel and typically produces a bowel movement within 2-4 days 5
• It can be used for up to 2 weeks initially; prolonged use beyond this requires physician supervision 5

Alternative First-Line Options

If PEG is unavailable or not tolerated:

• Bisacodyl 10-15mg once daily for faster relief, though it carries risk of colonic dependency with prolonged use 2, 6
• Senna 15-30mg once daily as another stimulant option 2
• Osmotic laxatives (lactulose or magnesium hydroxide) can be added if initial therapy fails 2

Important caveat: Avoid magnesium-based laxatives in patients with renal impairment due to risk of hypermagnesemia 2

Third-Line: Escalation for Persistent Constipation

If symptoms persist despite PEG:

• Increase bisacodyl to 10-15mg two to three times daily 2
• Add alternative osmotic laxatives such as lactulose or magnesium hydroxide 2
• Consider newer agents (intestinal secretagogues like linaclotide or prokinetic agents like prucalopride) if over-the-counter options fail 1, 6

Special Populations

Opioid-Induced Constipation

Start prophylactic stimulant laxative (senna or bisacodyl) with the first opioid dose, as opioid-induced constipation does not improve over time unlike other opioid side effects 1, 2, 3

• Osmotic or stimulant laxatives are generally preferred for opioid-induced constipation 1
• Avoid bulk laxatives (psyllium) for opioid-induced constipation 1
• For laxative-refractory cases, consider methylnaltrexone 0.15mg/kg subcutaneously every other day or naloxegol, which relieve constipation without compromising analgesia 1, 2
• Combination opioid agonist/antagonist agents (oxycodone + naloxone) are associated with lower risk of constipation 1

Elderly Patients

• Higher incidence of diarrhea occurs at the recommended 17g PEG dose in geriatric nursing home patients; discontinue if diarrhea develops 5
• Pay particular attention to medication review, living situation, and ensure adequate toilet access 1

Management of Fecal Impaction

If digital rectal examination reveals fecal impaction:

• Digital fragmentation and extraction of the stool 1
• Followed by enema (water or oil retention) or suppository to facilitate passage 1
• Then oral PEG once the distal colon is partially emptied 1
• For proximal impaction without complete obstruction, lavage with PEG solutions containing electrolytes may help 1

Common Pitfalls to Avoid

• Do not use prophylactic laxatives routinely except when starting opioid therapy, as prolonged use leads to dependency and rebound constipation is a myth that has been debunked 4, 3, 7
• Do not assume fiber deficiency is the cause; many patients with severe constipation worsen with increased fiber intake 7
• Do not assume increased fluid intake alone will treat constipation unless there is evidence of dehydration 7
• Do not perform colonoscopy in patients without alarm symptoms or who are under 50 years old without prior colorectal cancer screening 1
• Do not diagnose "autointoxication" or attribute systemic symptoms to constipation; this theory has been thoroughly debunked 7

When to Refer for Specialized Testing

Consider anorectal manometry and defecography if:

• No response to over-the-counter laxatives after adequate trial 1, 6
• Symptoms suggest defecatory disorder: sensation of incomplete evacuation, need for digital manipulation, or paradoxical puborectalis contraction on digital rectal examination 1
• Pelvic floor biofeedback therapy is highly effective for evacuation disorders and should be pursued before surgical options 3, 6

Colonic transit studies and manometry are reserved for patients who fail both laxatives and biofeedback therapy to identify slow-transit constipation that may require colectomy in specific refractory cases 6