What are the signs of postoperative ileus?

Signs of Postoperative Ileus

Postoperative ileus presents with a characteristic tetrad: abdominal distension, nausea/vomiting, absence of flatus, and delayed bowel movements, typically persisting beyond 3 days after surgery. 1, 2

Clinical Presentation

Cardinal Signs

• Abdominal distension is the most consistent physical finding 1
• Nausea and vomiting occur due to accumulation of gastrointestinal secretions and gas 3, 2
• Absence of flatus or bowel movements beyond the expected postoperative period 4, 2
• Crampy, intermittent abdominal pain (distinct from the continuous pain of mechanical obstruction) 1

Physical Examination Findings

• Absent or high-pitched bowel sounds on auscultation 1
• Tympanic percussion due to gas accumulation 2
• Generalized abdominal tenderness without peritoneal signs (unless complications develop) 1

Timing Considerations

Normal postoperative ileus resolves within specific timeframes for different bowel segments: small bowel function returns within 24 hours, gastric function within 24-48 hours, and colonic function within 48-72 hours. 2, 5 Ileus persisting beyond 3 days postoperatively is considered prolonged and pathological. 1, 2

Warning Signs Requiring Urgent Evaluation

High-Risk Features

• Tachycardia is the most alarming early postoperative sign, particularly after bariatric surgery 1
• Fever suggests possible anastomotic leak or ischemia 1
• Elevated white blood cell count raises suspicion for complications 1
• Elevated lactic acid indicates potential bowel ischemia 1
• Hemodynamic instability (hypotension, persistent tachycardia) 1

Imaging Signs of Complications

When imaging is performed, concerning findings include:

• Abnormal bowel wall enhancement (decreased or increased) suggesting ischemia 1
• Bowel wall thickening 1
• Mesenteric edema 1
• Pneumatosis or mesenteric venous gas indicating advanced ischemia 1
• Free air (beyond expected postoperative pneumoperitoneum) 1

Distinguishing Ileus from Mechanical Obstruction

Key differentiating features:

• Ileus: Diffuse, constant abdominal distension with minimal pain; absent or hypoactive bowel sounds 1
• Mechanical obstruction: Intermittent crampy pain; high-pitched or "tinkling" bowel sounds; more localized distension 1

CT imaging achieves >90% diagnostic accuracy in distinguishing ileus from mechanical small bowel obstruction 1

Special Populations

Post-Bariatric Surgery Patients

• Epigastric pain with acute onset (80% of cases) is characteristic 1
• Cramping/colicky nature (65% of cases) 1
• Symptoms may present months to years postoperatively (median 9 months for internal hernia) 1
• Laboratory values often remain normal despite significant pathology 1

Pregnant Patients Post-RYGB

• Vomiting is uncommon after gastric bypass due to lack of reservoir 1
• Absence of typical symptoms can delay diagnosis 1
• Lower threshold for imaging is warranted 1

Laboratory Abnormalities

While not diagnostic, associated findings include:

• Electrolyte derangements (hypokalemia, hypomagnesemia) both cause and result from ileus 1, 4
• Elevated serum amylase may occur 1
• Metabolic acidosis particularly with ureteral stenting issues 1

Common Pitfall

The most critical error is attributing all postoperative gastrointestinal symptoms to "normal" ileus without considering mechanical obstruction, anastomotic leak, or ischemia. 1 Any patient with persistent symptoms beyond 3 days, fever, tachycardia, or severe pain requires imaging evaluation rather than continued conservative management. 1, 2