What to look for in a patient with slight abdominal distention?

Evaluation of Slight Abdominal Distention

In a patient with slight abdominal distention, immediately assess for signs of bowel ischemia through focused physical examination, blood gas analysis, and lactate levels, while simultaneously obtaining plain abdominal radiographs to identify potential mechanical causes such as sigmoid volvulus or bowel obstruction. 1

Critical Initial Assessment

Physical Examination Findings to Identify

• Assess bowel sounds carefully – diminished sounds suggest mechanical obstruction, while high-pitched rushes indicate active obstruction 1, 2
• Perform digital rectal examination – an empty rectum is classic for sigmoid volvulus, while the presence of stool may suggest functional causes 1, 3
• Look for asymmetric gaseous distention with emptiness of the left iliac fossa – this pattern is pathognomonic for sigmoid volvulus, though challenging to detect 1
• Check for peritoneal signs – their absence does NOT exclude bowel ischemia, which is a critical pitfall 1
• Palpate for tender masses – particularly in the lower quadrants, which may indicate volvulus or obstruction 2

Essential Laboratory Testing

• Blood gas and lactate levels are crucial – these help identify bowel ischemia, though normal lactate does not exclude it 1
• Complete blood count and inflammatory markers (C-reactive protein, procalcitonin) to assess for infection or ischemia 1
• Electrolytes and renal function – elderly patients with distention often develop dehydration and renal insufficiency 1

Imaging Strategy

First-Line Imaging

Obtain plain abdominal radiographs (anteroposterior and lateral views) immediately – these identify the classic "coffee bean sign" of sigmoid volvulus with 89% sensitivity and can detect free air from perforation 1

When to Escalate to CT

Proceed directly to contrast-enhanced CT abdomen/pelvis if: 1

• Plain radiographs are non-diagnostic
• Clinical suspicion for bowel ischemia or perforation exists
• The patient has hemodynamic instability (though do not delay surgery for imaging in this scenario) 1

CT provides superior information about:

• The exact site and cause of obstruction 1
• Presence of bowel ischemia (use IV contrast to assess bowel wall perfusion) 1
• Complications such as perforation or abscess 1

Key Clinical Contexts

Mechanical Obstruction Pattern

If the patient presents with:

• Acute onset (hours to days) with pain, constipation, and vomiting 1
• Risk factors: elderly, institutionalized, on psychotropic medications causing constipation 1
• Previous episodes: 30-41% of sigmoid volvulus patients report prior distention 1

Functional Distention Pattern

If the patient has:

• Chronic, intermittent symptoms without alarm features 1, 3, 4
• Meal-related distention suggesting abdominophrenic dyssynergia 1, 3
• Subjective bloating exceeding objective findings 5, 6

Critical Pitfalls to Avoid

• Do not assume absence of peritonitis means absence of bowel ischemia – ischemia can occur without peritoneal signs 1
• Do not attribute all distention to gas accumulation – even 10% increases in gas can trigger significant distention through abdominophrenic dyssynergia in functional disorders 1, 3
• Do not miss ovarian cancer in women ≥50 years – bloating and distention are common presenting symptoms 3, 4
• Do not rely solely on patient history in elderly or neuropsychiatric patients – history may be unreliable or absent 1
• Do not delay imaging if clinical suspicion is high – plain radiographs may be non-diagnostic in many cases 1

Alarm Features Requiring Urgent Investigation

• Unintentional weight loss 4
• Gastrointestinal bleeding 4
• Persistent vomiting 4
• Iron-deficiency anemia 4
• Fever, tachycardia, or hypotension 1
• Signs of peritoneal irritation 1