What can I do if I'm unable to have a bowel movement?

Management of Constipation

Start with a stimulant laxative (senna or bisacodyl 10-15 mg, 2-3 times daily) as first-line therapy, aiming for one non-forced bowel movement every 1-2 days. 1

Initial Assessment

Before starting treatment, you must rule out:

• Fecal impaction - perform digital rectal exam 2, 1
• Bowel obstruction - assess for abdominal distension, absent bowel sounds, vomiting 2, 1
• Metabolic causes: hypercalcemia, hypokalemia, hypothyroidism, diabetes mellitus 2, 1
• Medication review - opioids, anticholinergics, antacids are common culprits 2

Stepwise Treatment Algorithm

Step 1: First-Line Therapy

• Stimulant laxative: Bisacodyl 10-15 mg, 2-3 times daily OR senna 2, 1
• Do NOT add stool softeners (like docusate) - evidence shows no additional benefit when combined with stimulant laxatives 2, 1
• Increase fluid intake and physical activity when appropriate 2, 1
• Consider dietary fiber ONLY if patient drinks at least 2 liters of fluid daily 1
• Avoid supplemental medicinal fiber (psyllium/Metamucil) - ineffective for medication-induced constipation 2, 1

Step 2: Persistent Constipation

If no improvement after initial therapy, reassess for impaction/obstruction, then add ONE of the following 2, 1:

• Polyethylene glycol (PEG) - one capful with 8 oz water twice daily 2, 1
• Lactulose 2, 1
• Magnesium hydroxide or magnesium citrate 2, 1
• Rectal bisacodyl suppositories twice daily 2, 1

Step 3: Refractory Constipation with Gastroparesis

If constipation persists and gastroparesis is suspected (early satiety, bloating, nausea):

• Add metoclopramide 10-20 mg, 2-3 times daily as a prokinetic agent 2, 1
• Note: Chronic metoclopramide use carries risk of tardive dyskinesia 2

Step 4: Advanced Therapies

For constipation unresponsive to standard laxatives:

• Newer secretagogues: linaclotide, lubiprostone, or plecanatide 3, 1
• Methylnaltrexone 0.15 mg/kg subcutaneously every other day (maximum once daily) for opioid-induced constipation that hasn't responded to laxatives 2
• Rifaximin 550 mg twice daily for 1-2 weeks if small intestinal bacterial overgrowth (SIBO) is suspected as contributing factor 3

Management of Impaction

If impaction is present:

• Glycerin suppositories 2
• Manual disimpaction if necessary 2
• Fleet, saline, or tap water enema - dilates bowel, stimulates peristalsis, lubricates stool 2

Critical Pitfalls to Avoid

• Don't waste time with stool softeners alone - they provide no benefit when added to stimulant laxatives 2, 1
• Don't rely on fiber supplements without ensuring adequate hydration (at least 2 liters daily) 1
• Don't forget to reassess for obstruction or impaction if treatment fails 2, 1
• Don't delay treatment - constipation occurs in approximately 50% of patients on opioids and should be treated prophylactically 2
• Don't aim for daily bowel movements - the goal is one non-forced bowel movement every 1-2 days 2, 1

Special Considerations

For opioid-induced constipation specifically:

• Always anticipate and treat prophylactically with stimulant laxatives 2
• Patients do NOT develop tolerance to opioid-induced constipation 2
• Consider opioid rotation to fentanyl or methadone if constipation is severe 2

Dietary modifications:

• Low FODMAP diet may help reduce bloating and gas, but avoid in malnourished patients 3
• Adequate fluid intake is essential before recommending fiber 1
• Peppermint oil may help with associated pain and discomfort 3

When medical management fails:

• Biofeedback therapy improves symptoms in over 70% of defecatory disorders 3
• Consider anorectal testing if no response to over-the-counter agents 4