What is the recommended diagnostic work‑up and step‑wise management of acute colonic pseudo‑obstruction (Ogilvie syndrome) in an adult postoperative or critically ill patient presenting with marked abdominal distension without mechanical obstruction?

Ogilvie Syndrome (Acute Colonic Pseudo-Obstruction): Diagnostic Work-Up and Management

Initial Diagnostic Approach

Begin with CT abdomen/pelvis with IV contrast as the primary diagnostic tool to exclude mechanical obstruction and identify complications requiring immediate surgery. 1, 2

Essential Clinical Assessment

• Document the presence of marked abdominal distension, which occurs in 65.3% of cases and has a positive likelihood ratio of 16.8 3
• Assess for absence of flatus (90% of cases) and absence of bowel movements (80.6% of cases) 3
• Auscultate for hyperactive or absent bowel sounds; absent sounds indicate progression to ischemia or strangulation with mortality up to 25% 3
• Perform digital rectal examination to exclude fecal impaction or distal mechanical obstruction 3

Critical Warning Signs Requiring Immediate Surgery

• Fever, tachycardia, tachypnea, confusion, or intense pain unresponsive to analgesics indicate bowel ischemia/strangulation 3
• Diffuse tenderness with guarding or rebound suggests peritonitis or perforation 3
• Elevated lactate, leukocytosis, or metabolic acidosis on laboratory testing 3

Imaging Protocol

• CT abdomen/pelvis with IV contrast is the diagnostic standard with >90% accuracy 4, 5
• Do not administer oral contrast in suspected high-grade obstruction, as it delays diagnosis and increases aspiration risk 5
• Plain abdominal radiographs have limited value (50-60% sensitivity) and should not delay CT imaging 4, 3
• Look for cecal diameter ≥12 cm, which indicates critical distension requiring intervention 6

Step-Wise Management Algorithm

Step 1: Immediate Interventions for All Patients (0-24 hours)

All patients without perforation or ischemia should receive initial conservative management 1, 2:

• Bowel rest (NPO status) 1
• Nasogastric tube decompression 6
• Rectal tube placement for distal decompression 6
• Aggressive IV fluid resuscitation to correct dehydration and electrolyte disturbances 1, 6
• Mobilization of the patient (avoid prolonged bed rest) 1
• Discontinue or minimize opioid narcotics and anticholinergic medications 6, 7
• Serial clinical and radiological monitoring at close intervals 6

Step 2: Patients Who Fail Conservative Management (24-48 hours)

If colonic distension persists after 24 hours of conservative therapy, or if cecal diameter is ≥12 cm, or if duration exceeds 3-4 days, proceed to pharmacologic decompression 6:

Neostigmine Administration

• Neostigmine leads to durable success in approximately 75% of patients 6
• Administer under continuous cardiac monitoring due to risk of bradycardia
• Have atropine immediately available for reversal of cholinergic side effects 6

Step 3: Refractory Cases (48-72 hours)

Patients who remain refractory to neostigmine should undergo endoscopic decompression 6, 7:

• Colonoscopic decompression with placement of a decompression tube achieves clinical success in 88.6% at first attempt and 92.5% at second attempt 7
• Complication rate of endoscopic treatment is approximately 3.8%, including risk of perforation and ischemic injury 7
• If endoscopic decompression fails after two attempts, or if complications occur, proceed to surgical intervention 7

Step 4: Surgical Intervention

Surgery is indicated for 1, 2, 6:

• Perforation or suspected bowel ischemia on imaging
• Failure of both neostigmine and endoscopic decompression
• Recurrent ACPO despite repeated medical and endoscopic management

Surgical options include cecostomy or segmental/subtotal colectomy 6

Critical Pitfalls to Avoid

• Never delay CT imaging in favor of plain radiographs alone, as physical examination and laboratory tests are neither sufficiently sensitive nor specific to detect strangulation 5, 3
• Do not confuse ACPO with mechanical obstruction or toxic megacolon; water-soluble contrast enema may be required for differentiation 6
• Recognize that 66.5% of cases follow surgery or trauma, and 63.2% of patients received IV narcotics prior to development of ACPO 7
• Overall hospital mortality is 21%, increasing to 25-50% when complications such as ischemia or perforation develop 6, 7

Special Considerations for Recurrent Cases

For patients with recurrent ACPO despite appropriate management, consider underlying chronic intestinal pseudo-obstruction or slow-transit colonic dysmotility 1. These patients may require referral to a specialized motility center for further evaluation with manometry and consideration of long-term management strategies 4.