What are the recommended imaging studies to identify adhesions?

Recommended Imaging Studies for Identifying Adhesions

CT scan with intravenous contrast is the preferred imaging modality for identifying adhesions, with approximately 90% accuracy in diagnosing small bowel obstruction caused by adhesions. 1

Primary Imaging Options

CT Scan

• CT with IV contrast is the primary diagnostic tool for suspected adhesions, especially when they cause small bowel obstruction 1
• While adhesions themselves are not directly visible on CT, the diagnosis is made by identifying a transition zone and excluding other causes of obstruction 1
• Multidetector-row CT (MDCT) offers improved diagnostic accuracy with 87% sensitivity and 90% specificity for identifying the etiology of small bowel obstruction 1
• CT can demonstrate architectural distortion and tethering in severe adhesive disease 1
• Signs that suggest adhesive obstruction on CT include a transition zone without other visible cause, closed-loop obstruction, and the "small bowel feces sign" 1

Water-Soluble Contrast Studies

• Water-soluble contrast agents are useful in both diagnosis and potential treatment of adhesive small bowel obstruction 1
• If contrast fails to reach the colon on an abdominal X-ray taken 24 hours after administration, this indicates failure of non-operative management with high sensitivity (96%) and specificity (98%) 1
• These studies can accurately predict the need for surgery and reduce hospital stay 1

Alternative Imaging Options

MRI

• Fast MRI using HASTE (Half-Fourier Acquisition Single-shot Turbo spin Echo) sequence has shown higher accuracy (96%) than helical CT (71%) in some studies for diagnosing bowel obstruction caused by adhesions 2
• MRI can be valuable in situations where radiation exposure is undesirable, such as in pregnant patients 1
• MRI can visualize adhesions between viscera, though with a tendency to over-diagnose 3

Ultrasound

• Abdominal ultrasound can determine the presence of adhesions between bowel and the abdominal wall with accuracy ranging from 76-100% 3
• Ultrasound is operator-dependent but in experienced hands can provide valuable information about bowel distension and free fluid 1
• Particularly useful in settings where CT is unavailable or when radiation exposure is a concern 1

Clinical Considerations and Pitfalls

Diagnostic Challenges

• Adhesions are not directly visible on standard imaging; diagnosis is typically made by excluding other causes of obstruction 1
• CT has limited sensitivity for low-grade or intermittent obstruction (48-50%) 1
• For suspected intermittent or low-grade obstruction, specialized techniques like CT enteroclysis or CT enterography may be needed 1

When to Consider Specialized Imaging

• CT enteroclysis (with nasojejunal intubation) offers improved sensitivity for subtle causes of mild obstructions but is not widely used due to practical challenges 1
• CT enterography (with oral contrast protocol) may be beneficial for better bowel distention though evidence for its use in detecting adhesions is limited 1
• For patients with virgin abdomen (no prior surgery), CT is essential to rule out other causes of obstruction before attributing symptoms to adhesions 1

Imaging in Specific Scenarios

• For suspected small bowel obstruction with signs of ischemia or perforation, immediate CT with IV contrast is mandatory 1
• In pregnant patients or those where radiation exposure is a concern, ultrasound followed by MRI if needed is the recommended approach 1
• Plain radiographs have limited value (sensitivity ~70%) and should not be relied upon as the sole imaging modality 1

By following this imaging approach, clinicians can accurately diagnose adhesions and determine appropriate management strategies, whether conservative or surgical, to optimize patient outcomes.