What is the initial management of functional constipation in the elderly in an Emergency Room (ER) setting?

Initial Management of Functional Constipation in Elderly Patients in the ER

In the ER setting, immediately perform a digital rectal examination to assess for fecal impaction, then initiate polyethylene glycol (PEG) 17 g/day as first-line treatment while addressing reversible causes and implementing non-pharmacological measures. 1, 2

Immediate Assessment in the ER

Rule out life-threatening causes first:

• Assess for bowel obstruction, perforation, or acute abdomen requiring surgical intervention 1
• Perform digital rectal examination (DRE) to identify fecal impaction or rectal masses 1
• Check for red flags: severe abdominal pain, distension, vomiting, fever, or signs of peritonitis 1

Identify and address reversible causes:

• Review medications causing constipation (opioids, anticholinergics, antacids, antidepressants) and discontinue non-essential agents 1
• Check electrolytes for hypercalcemia, hypokalemia, and assess for hypothyroidism or diabetes 1
• Evaluate for dehydration and renal function, particularly important in elderly patients 1

Immediate Treatment Based on DRE Findings

If fecal impaction is present:

• Perform manual disimpaction through digital fragmentation and extraction of stool 1
• Follow with glycerin suppositories or isotonic saline enema (preferred over sodium phosphate enemas in elderly due to lower adverse effects) 1
• Avoid enemas if: neutropenia, thrombocytopenia, recent pelvic surgery, recent radiotherapy, or suspected perforation 1

If no impaction but rectum is full:

• Administer rectal bisacodyl suppository or isotonic saline enema as first-line therapy 1
• This is particularly appropriate for elderly patients with swallowing difficulties 1

First-Line Pharmacological Treatment

Polyethylene glycol (PEG) 17 g/day is the preferred initial oral laxative for elderly patients:

• Superior efficacy and excellent safety profile in elderly patients 1, 2
• Does not require increased fluid intake like bulk-forming agents 2, 3
• Generally produces bowel movement in 1-3 days 4
• Safe in patients with cardiac and renal comorbidities when monitored appropriately 1

Alternative first-line options if PEG unavailable or not tolerated:

• Osmotic laxatives: lactulose 15-30 mL daily 1, 5
• Stimulant laxatives: senna (produces bowel movement in 6-12 hours), bisacodyl 10-15 mg 2-3 times daily, or sodium picosulfate 1, 6
• Goal: one non-forced bowel movement every 1-2 days 1

Critical Medications to AVOID in Elderly ER Patients

Do not prescribe these agents:

• Bulk-forming laxatives (psyllium, methylcellulose) in non-ambulatory patients or those with low fluid intake—risk of mechanical obstruction 1, 2
• Liquid paraffin in bed-bound patients or those with swallowing disorders—risk of aspiration lipoid pneumonia 1, 2
• Magnesium-based laxatives (magnesium hydroxide, magnesium citrate) in patients with renal impairment—risk of hypermagnesemia 1, 2
• Docusate alone—ineffective for treatment or prevention 5

Non-Pharmacological Measures to Initiate in ER

Provide specific discharge instructions:

• Ensure toilet access, especially for patients with mobility limitations 1, 2
• Educate on optimized toileting: attempt defecation twice daily, 30 minutes after meals (when gastrocolic reflex is strongest), strain no more than 5 minutes 1, 2
• Recommend fluid intake of at least 1.5 liters daily if not contraindicated 5
• Encourage any level of physical activity within patient's capability 5

ER Discharge Algorithm

Step 1: Start PEG 17 g daily mixed with 8 oz water 2, 5

Step 2: If PEG contraindicated or unavailable, use lactulose 15-30 mL daily OR senna/bisacodyl 1, 5

Step 3: If impaction was present, prescribe maintenance laxative regimen to prevent recurrence 1

Step 4: Arrange follow-up within 3-5 days to assess response 1

Common Pitfalls in ER Management

Avoid these errors:

• Prescribing fiber supplements without adequate hydration assessment—worsens constipation in elderly 2, 5
• Using docusate as monotherapy—ineffective 5
• Failing to perform DRE—misses impaction requiring immediate mechanical relief 1
• Prescribing magnesium laxatives without checking renal function—risk of toxicity 1, 2
• Administering sodium phosphate enemas to elderly patients—higher adverse effects than isotonic saline 1

Special Considerations for Opioid Users

If patient is on chronic opioids:

• Prescribe prophylactic laxative immediately (stimulant or osmotic laxative preferred) 1
• Consider peripherally acting mu-opioid receptor antagonists (methylnaltrexone, naloxegol) for refractory opioid-induced constipation, though these are typically not initiated in ER 1

Monitoring Requirements

Before discharge, ensure:

• Renal function checked if prescribing any laxative in elderly 1
• Cardiac status assessed if patient has heart failure and will be on laxatives with diuretics—risk of electrolyte imbalances 1
• Patient/caregiver understands warning signs requiring return to ER: severe pain, vomiting, inability to pass gas, fever 1