How is constipation managed in patients with a colostomy?

Constipation Management in Colostomy Patients

Start with dietary modifications including increased fiber and fluid intake, and if unsuccessful after 3 months, add osmotic laxatives (polyethylene glycol 17g daily) or stimulant laxatives (senna, bisacodyl) as first-line pharmacologic therapy. 1, 2

Initial Conservative Management

• Discontinue all medications that can cause constipation when feasible before initiating other interventions 1
• Increase dietary fiber and fluid intake as the first-line intervention, which successfully resolves constipation in approximately 60% of colostomy patients within 3 months 2
• Educate patients to attempt defecation at least twice daily, preferably 30 minutes after meals, straining no more than 5 minutes 1
• Ensure privacy and comfort for normal defecation, use positioning aids like footstools to assist gravity, and increase physical activity within patient limits 1

Important distinction: Constipation is a relevant concern for colostomy patients (who typically have formed stool once daily), whereas high output is the primary concern for ileostomy patients 3. The AGA guidelines note that colostomy output is easier to manage than ileostomy output due to its consistency 3.

Pharmacologic Therapy When Diet Fails

When dietary modifications alone are insufficient after a 3-month trial:

• Start with osmotic laxatives (polyethylene glycol 17g daily, lactulose, or magnesium salts) OR stimulant laxatives (senna, bisacodyl, glycerol suppositories) 1
• Add psyllium-based bulk-forming agents as adjunctive therapy 2
• Consider probiotics in combination with the above agents 2
• Add prokinetic agents (metoclopramide 3 times daily) if symptoms persist despite the above measures 2

Critical pitfall: Do not use bulk laxatives in non-ambulatory patients with low fluid intake, as this can worsen obstruction 1

Second-Line Agents for Refractory Cases

• When symptoms do not respond to simple laxatives, consider newer agents like linaclotide or lubiprostone 1
• Linaclotide increases complete spontaneous bowel movements by approximately 1.5 per week compared to placebo and works by activating ion channels on enterocytes to soften stools and accelerate gut transit 1

When to Perform Further Testing

• Perform anorectal testing only in patients who do not respond to the initial therapeutic trial of dietary modifications and laxatives 1
• Conduct a careful digital rectal examination including assessment of pelvic floor motion during simulated evacuation before referral for anorectal manometry 1
• A normal digital rectal examination does NOT exclude defecatory disorders 1

Special Considerations

The evidence base for constipation management in colostomy patients is limited, with most guidelines addressing general constipation or high-output ostomy problems rather than constipation specifically in colostomy patients. The 2017 prospective study by the Wound, Ostomy and Continence Nurses Society provides the most direct evidence, demonstrating that a stepwise approach starting with conservative measures is effective 2. The AGA guidelines, while not specifically addressing colostomy patients, provide the framework for pharmacologic management when conservative measures fail 4, 1.

Avoid extensive metabolic testing or colonoscopy without alarm features or appropriate screening indications 1