Immediate Management of Acute Abdominal Pain with Distension and Rigid Abdomen
Obtain CT abdomen and pelvis with IV contrast immediately—this patient requires urgent imaging to rule out bowel ischemia, perforation, or high-grade obstruction, as clinical examination alone has poor accuracy and delayed diagnosis of ischemia carries up to 25% mortality. 1
Initial Resuscitation and Stabilization
- Begin IV crystalloid resuscitation immediately while arranging imaging, as fluid resuscitation is the cornerstone of initial supportive treatment 1
- Insert a nasogastric tube for gastric decompression to prevent aspiration pneumonia, even though she is passing some flatus 1
- Place a Foley catheter to monitor urine output and assess hydration status 1
- Administer IV anti-emetics and maintain strict NPO status 1
- Obtain complete blood count (looking for leukocytosis >10,000/mm³ suggesting peritonitis), electrolytes (particularly potassium), renal function tests, lactate (elevated in ischemia), and CRP (>75 suggests peritonitis) 1
Critical Imaging Decision
CT abdomen and pelvis with IV contrast is the diagnostic gold standard with >90% accuracy for identifying obstruction, its cause, and life-threatening complications. 1, 2
- Do NOT give oral contrast in suspected high-grade obstruction—the non-opacified fluid in dilated bowel provides adequate intrinsic contrast 1
- IV contrast is essential to evaluate for bowel ischemia and identify the underlying etiology 1
Red Flag CT Findings Requiring Emergency Surgery
Any of these findings mandate immediate surgical consultation: 1
- Absent or abnormal bowel wall enhancement (indicates ischemia)
- Mesenteric edema or haziness
- Bowel wall thickening
- Pneumatosis intestinalis or portal venous gas
- Free intraperitoneal air (perforation)
- Closed loop obstruction with mesenteric swirl
Differential Diagnosis Based on Left Lower Quadrant Predominance
Acute sigmoid diverticulitis is the most common cause of left lower quadrant pain in adults and accounts for the majority of cases in Western populations. 3, 2
- Complicated diverticulitis with obstruction can cause progressive vomiting, distension, and inability to pass flatus despite recent small stool 2
- Perforated diverticulitis with peritonitis presents with rigid abdomen and carries mortality up to 67.8% with septic shock 2
- Sigmoid volvulus presents with acute onset pain, marked distension, and obstipation—CT shows characteristic "whirl sign" 4
Management Algorithm Based on Imaging
If CT Shows Signs of Ischemia or Perforation:
- Immediate surgical consultation—mortality increases from 10% to 25-30% with bowel necrosis 1
- Start broad-spectrum antibiotics immediately after blood cultures 2
- Prepare for emergency laparotomy
If CT Shows Uncomplicated Diverticulitis:
- Percutaneous drainage plus IV antibiotics for abscesses ≥3-4 cm 2
- In immunocompetent patients without sepsis, antibiotics may not be necessary as they don't accelerate recovery 2
If CT Shows Low-Grade Partial Obstruction:
- Continue conservative management with nasogastric decompression, IV fluids, and pain control 1
- Most low-grade obstructions resolve within 48-72 hours non-operatively 1
- Repeat imaging at 24 hours if no clinical improvement 1
Critical Pitfalls to Avoid
- Do not mistake the passage of small soft stool and flatus as excluding high-grade obstruction—incomplete obstruction can allow minimal passage while still requiring urgent intervention 1
- Do not delay CT imaging based on "reassuring" bowel sounds—physical examination has only 48% sensitivity for detecting strangulation 1
- Do not use plain abdominal radiography—it has only 50-60% sensitivity with 20-30% inconclusive results and will delay definitive diagnosis 3, 1, 5
- Rigid abdomen with distension suggests peritonitis in 82.5% of cases—this finding mandates immediate imaging and surgical evaluation 6