What is the best approach to manage abdominal distention in an elderly patient?

Management of Abdominal Distention in Elderly Patients

Begin with plain abdominal radiographs to identify the most common causes in the elderly—sigmoid volvulus (coffee bean sign) or large bowel obstruction from colorectal cancer—then proceed to CT imaging if the diagnosis remains unclear or if bowel ischemia is suspected. 1, 2

Initial Clinical Assessment

Focus your history and physical examination on these specific findings:

• Classic triad of symptoms: Abdominal pain, constipation, and vomiting (late sign), with 30-41% reporting previous episodes of distention 1
• Physical examination findings: Look for asymmetric gaseous distention with emptiness of the left iliac fossa (pathognomonic for sigmoid volvulus, though challenging to detect), diminished bowel sounds, and empty rectum on digital rectal examination 1
• Critical laboratory tests: Complete blood count, serum albumin, electrolytes, renal function, blood gas, and lactate levels to assess for bowel ischemia and dehydration-related renal insufficiency 1

Important caveat: The absence of peritonitis does not exclude bowel ischemia, and hyperlactatemia may be absent even with ischemic bowel. 1

Diagnostic Imaging Algorithm

Step 1: Plain Abdominal Radiographs

• Obtain upright and supine films immediately 1
• Look for the "coffee bean sign" projecting toward the upper abdomen (sigmoid volvulus) or the "northern exposure sign" (above the transverse colon) 1
• Chest radiographs detect free air if perforation has occurred 1

Step 2: CT Imaging (when indicated)

• Proceed to CT if: Diagnosis uncertain on plain films, clinical suspicion for bowel ischemia, or need to exclude other diagnoses (colorectal cancer, diverticulitis, ischemic colitis) 1, 2
• CT is particularly valuable in elderly patients because clinical examination is often unreliable, and there is higher prevalence of complicated disease requiring urgent intervention 2, 3
• CT influences treatment plans in 65% of elderly patients and significantly affects ED disposition (65% of admissions with positive CT, 63% of discharges with negative CT) 3

Differential Diagnosis Specific to Elderly

Most common causes of abdominal distention in elderly patients (in order of frequency):

1. Large bowel obstruction from colorectal cancer (most common site and cause in elderly) 2
2. Sigmoid volvulus (classic presentation with coffee bean sign) 1
3. Small bowel obstruction (18% of acute abdominal presentations) 3
4. Fecal impaction (often presents with paradoxical overflow diarrhea) 4, 5
5. Diverticulitis (9% of cases, often complicated due to delayed diagnosis) 3
6. Bowel ischemia (acute mesenteric ischemia or ischemic colitis, much more common after age 80) 2

Management Based on Etiology

For Sigmoid Volvulus:

• Initial management depends on presence of peritonitis or bowel ischemia 1
• If no peritonitis: Consider endoscopic decompression 1
• If peritonitis present: Urgent surgical consultation 1

For Fecal Impaction:

• Perform digital rectal examination to confirm diagnosis 4, 5
• Manual disimpaction with pre-medication (analgesic ± anxiolytic) 4
• Immediately initiate polyethylene glycol (PEG) 17 g/day as maintenance therapy to prevent recurrence 4, 6
• Add bisacodyl suppository if oral laxatives insufficient 4
• Use isotonic saline enemas (500-1000 mL), NOT sodium phosphate enemas, due to risk of electrolyte disturbances in elderly 1, 6

For Constipation-Related Distention:

• First-line pharmacological treatment: PEG 17 g/day (excellent safety profile in elderly) 1, 4
• Avoid bulk-forming laxatives in non-ambulatory patients with low fluid intake (risk of mechanical obstruction) 1, 6
• Avoid liquid paraffin in bed-bound patients (risk of aspiration lipoid pneumonia) 1, 6
• Avoid magnesium-containing laxatives in patients with renal impairment (risk of hypermagnesemia) 1, 4

Critical Pitfalls to Avoid

Common diagnostic errors in elderly:

• Assuming functional bloating when organic pathology is present (43% of diagnoses unsuspected before CT) 3
• Missing small bowel obstruction, diverticulitis, or colonic obstruction on clinical examination alone 3
• Overlooking extra-abdominal causes (inferior myocardial infarction, pneumonia) that present with abdominal distention 2

Medication-related considerations:

• Review all medications and withdraw constipating agents when possible 4, 5
• Avoid metoclopramide in elderly due to increased risk of parkinsonian-like side effects and tardive dyskinesia; use lowest effective dose if necessary and discontinue if extrapyramidal symptoms develop 7

Non-Pharmacological Measures

Implement these interventions before or alongside pharmacological treatment:

• Ensure toilet access, especially for patients with decreased mobility 1, 4
• Optimize toileting habits: attempt defecation twice daily, 30 minutes after meals, strain no more than 5 minutes 1, 4
• Increase fluid intake to at least 1.5 liters daily (within patient limits) 4
• Provide dietetic support to manage decreased food intake from anorexia of aging or chewing difficulties 1, 4