What is the best approach for managing constipation in an adult or geriatric patient with a history of gastrointestinal problems and unknown abdominal X-ray results in an urgent care setting?

Managing Constipation in Urgent Care: Adult and Geriatric Patients with GI History

In the urgent care setting, immediately perform a digital rectal examination to rule out fecal impaction and bowel obstruction before initiating any laxative therapy, then start polyethylene glycol (PEG) 17 g/day as first-line treatment if no obstruction is present. 1, 2

Critical First Step: Rule Out Bowel Obstruction

Before prescribing any laxative, you must exclude bowel obstruction, which can present as constipation in elderly patients with GI history 1:

• Perform digital rectal examination immediately to assess for fecal impaction, sphincter tone, rectal masses, and blood 1, 3
• Examine for peritoneal signs including abdominal distension (positive likelihood ratio 16.8 for obstruction), tenderness, and absent bowel sounds 1
• Check all hernia orifices (umbilical, inguinal, femoral) and surgical scars, as incarcerated hernias can cause obstruction 1
• Assess vital signs for tachycardia, hypotension, or signs of shock suggesting ischemia or perforation 1

If obstruction is suspected clinically, obtain a plain abdominal X-ray (84% sensitivity, 72% specificity for large bowel obstruction) to image faecal loading extent and exclude mechanical obstruction before any laxative administration 1

When Laxatives Are Contraindicated

Stop immediately and refer for emergency evaluation if 4:

• Rectal bleeding is present 4
• Nausea, vomiting, or abdominal pain worsens after laxative initiation 4
• Peritoneal signs develop 1
• Sudden change in bowel habits lasting >2 weeks 4

First-Line Pharmacological Treatment

Once obstruction is excluded, prescribe polyethylene glycol (PEG) 17 g/day as first-line therapy 2, 5:

• PEG has the best efficacy and safety profile in elderly patients, supported by systematic review evidence 2, 5
• PEG is safe for long-term use (up to 6 months) in geriatric populations 5
• Instruct patients to take with adequate fluids (at least 8 oz water) to prevent paradoxical obstruction 4, 6

Alternative Laxative Options

If PEG is not tolerated or contraindicated 1, 2:

• Osmotic laxatives: Lactulose or magnesium hydroxide (but avoid magnesium in renal impairment due to hypermagnesemia risk) 1, 2
• Stimulant laxatives: Senna, bisacodyl, or sodium picosulfate 1, 2

Laxatives to Avoid in Urgent Care

Do not prescribe these agents in elderly patients with GI history 1, 2, 6:

• Bulk-forming laxatives (psyllium): Contraindicated in non-ambulatory elderly with low fluid intake—can cause mechanical obstruction requiring hospitalization 1, 2, 6
• Liquid paraffin: Risk of aspiration lipoid pneumonia in bed-bound patients or those with swallowing disorders 1, 2
• Docusate alone: Ineffective for both prevention and treatment of constipation 2, 7

Management of Fecal Impaction

If digital rectal exam reveals impaction 1, 2:

• Use suppositories or enemas as first-line therapy when rectum is full 1
• Glycerol suppositories or phosphate enemas are effective 1
• Isotonic saline enemas are safer than sodium phosphate enemas in elderly patients 7
• Manual disimpaction under anesthesia may be needed if oral/rectal treatments fail 1

Enemas are contraindicated in 1:

• Neutropenia or thrombocytopenia
• Recent colorectal/gynecological surgery
• Recent pelvic radiotherapy
• Undiagnosed abdominal pain

Non-Pharmacological Measures to Prescribe Concurrently

Provide specific instructions for 1, 2:

• Increase fluid intake to at least 1.5 liters daily 7
• Encourage mobility within patient limits (even bed-to-chair transfers help) 1, 2
• Optimize toileting: attempt defecation twice daily, 30 minutes after meals, strain no more than 5 minutes 2, 7
• Use small footstool to assist gravity and pressure during defecation 1

Critical Pitfalls in Urgent Care

Common errors that worsen outcomes 1, 2, 7:

1. Starting laxatives without rectal exam: Fecal impaction with overflow can mimic simple constipation—laxatives worsen this 7, 3
2. Prescribing bulk laxatives to immobile elderly: This causes obstruction requiring hospitalization 2, 6
3. Ignoring medication review: NSAIDs and other common medications cause colitis mimicking constipation 8
4. Inadequate fluid instructions with laxatives: Leads to paradoxical worsening and potential obstruction 4, 6

Follow-Up Instructions

Instruct patients to return immediately if 4:

• Rectal bleeding develops
• Abdominal pain, nausea, or bloating worsens
• Diarrhea occurs (may indicate overflow from impaction)
• No bowel movement within 3 days despite treatment

Arrange follow-up within 1 week if symptoms persist, as laxatives should not be used longer than 1 week without physician reassessment 4