What is the best approach for managing functional constipation with abdominal pain in an elderly patient in the Emergency Room (ER)?

Management of Functional Constipation in Elderly Patients Presenting with Abdominal Pain in the ER

In the emergency room, immediately perform a digital rectal examination to rule out fecal impaction, and if present, proceed with manual disimpaction followed by enemas, then initiate polyethylene glycol (PEG) 17 g/day as maintenance therapy. 1, 2, 3

Immediate Assessment in the ER

Critical First Step: Rule Out Fecal Impaction

• Perform digital rectal examination (DRE) on all elderly patients presenting with constipation and abdominal pain to identify fecal impaction or a full rectum, as this finding completely changes your management approach 1, 3
• Check for alarm features that would contraindicate standard treatment: suspected perforation, gastrointestinal bleeding, recent colorectal surgery, severe colitis, toxic megacolon, or paralytic ileus 1
• Obtain a complete medication list, as polypharmacy is a leading cause of constipation in the elderly, particularly anticholinergics, opioids, calcium channel blockers, and iron supplements 1

When Fecal Impaction is Present

If DRE identifies fecal impaction, suppositories and enemas become first-line therapy, not oral laxatives 1

• Manual disimpaction through digital fragmentation and extraction is the definitive initial treatment in the absence of suspected perforation or bleeding 1, 3
• Follow manual disimpaction with isotonic saline enemas (preferred over sodium phosphate enemas in elderly patients due to lower risk of electrolyte disturbances) 1, 3
• Glycerin suppositories can be used as an adjunct after initial manual extraction 1, 3
• After successful disimpaction, immediately initiate PEG 17 g/day as maintenance therapy to prevent recurrence 1, 2, 3

Management When No Impaction is Present

First-Line Pharmacological Treatment

Polyethylene glycol (PEG) 17 g/day is the preferred first-line laxative for elderly patients due to its superior efficacy and excellent safety profile, particularly in those with cardiac or renal comorbidities 1, 2

• PEG does not require high fluid intake like bulk-forming agents, making it ideal for frail elderly patients who may have difficulty maintaining adequate hydration 1, 2, 4
• PEG does not cause electrolyte imbalances, unlike magnesium-based laxatives which risk hypermagnesemia in renal impairment 1, 2

Alternative Laxative Options (If PEG Not Tolerated)

If PEG is contraindicated or not tolerated, proceed in this order:

1. Osmotic laxatives: Lactulose 15-30 mL daily 1, 2
2. Stimulant laxatives: Senna, bisacodyl 10-15 mg 2-3 times daily, or sodium picosulfate 1, 2
3. Consider adding a prokinetic agent like metoclopramide if gastroparesis is suspected 1

Critical Medications to AVOID in Elderly Patients

Do not prescribe bulk-forming laxatives (psyllium, methylcellulose) to non-ambulatory elderly patients with low fluid intake due to significantly increased risk of mechanical bowel obstruction 1, 2, 4

• Avoid liquid paraffin in bed-bound patients or those with swallowing disorders due to risk of aspiration lipoid pneumonia 1, 2
• Use magnesium-based laxatives (magnesium hydroxide, magnesium citrate) with extreme caution in elderly patients, particularly those with any degree of renal impairment, due to hypermagnesemia risk 1, 2
• Docusate (stool softener) is ineffective as monotherapy and should not be relied upon for constipation management 1, 2, 3

Non-Pharmacological Measures (Initiate Simultaneously)

While pharmacological treatment addresses the acute problem, implement these measures to prevent recurrence:

• Ensure toilet access, especially critical for patients with decreased mobility who may be avoiding defecation due to difficulty reaching facilities 1, 2
• Optimize toileting habits: Educate patients to attempt defecation twice daily, 30 minutes after meals (when gastrocolic reflex is strongest), straining no more than 5 minutes 1, 2
• Increase fluid intake to at least 1.5 liters daily if not contraindicated by cardiac or renal disease 1, 5
• Encourage physical activity within patient limitations, as even minimal movement from bed to chair stimulates bowel function 1, 5
• Provide dietetic support and address decreased food intake related to anorexia of aging or chewing difficulties 1, 2

Special Considerations for Opioid-Induced Constipation

If the patient is on opioid therapy:

• All patients receiving opioids should be prescribed a concomitant laxative prophylactically 1
• First-line treatment remains osmotic (PEG) or stimulant laxatives (senna, bisacodyl) 1
• Do not use bulk laxatives like psyllium for opioid-induced constipation 1
• If standard laxatives fail, consider peripherally acting mu-opioid receptor antagonists (PAMORAs) such as methylnaltrexone 0.15 mg/kg every other day, though cost may be prohibitive 1

Monitoring and Follow-Up

• Regular monitoring is essential for elderly patients with chronic kidney or heart failure, especially when diuretics or cardiac glycosides are co-prescribed, due to risk of dehydration and electrolyte imbalances 1
• Laxative selection must be individualized based on cardiac and renal comorbidities, potential drug interactions, and adverse effects 1, 2
• For patients with recurrent fecal impaction or swallowing difficulties, rectal measures (suppositories or enemas) may become the preferred ongoing treatment rather than oral agents 1, 3

Common Pitfalls to Avoid

• Do not discharge elderly patients with constipation without performing DRE, as undiagnosed fecal impaction will lead to treatment failure and rapid return to the ER 1, 3, 6
• Do not prescribe fiber supplements to patients who cannot maintain adequate hydration, as this increases obstruction risk 1, 4
• Do not use sodium phosphate enemas in elderly patients due to electrolyte disturbance risk; use isotonic saline enemas instead 1, 3
• Recognize that abdominal pain with constipation requires exclusion of serious pathology (obstruction, perforation, ischemia) before attributing symptoms to functional constipation alone 1