Diagnostic Approach to Dilated Bowel Loops

Primary Diagnostic Categories

The American College of Radiology recommends CT scan with IV contrast as the definitive first-line test to distinguish between mechanical obstruction and functional ileus, and to identify the underlying cause, with a sensitivity of over 90% for diagnosing obstruction and identifying the cause 1, 2
Adhesive disease is the most common cause of mechanical small bowel obstruction, accounting for approximately 70% of cases 3
Hernias, including internal or external through abdominal wall defects, can cause mechanical small bowel obstruction 4, 5
Malignancy, including primary bowel tumors or extrinsic compression from masses, can cause mechanical small bowel obstruction 1
Strictures from inflammatory bowel disease, particularly Crohn's disease with transmural inflammation, can cause mechanical small bowel obstruction 6
Intussusception, more common in pediatric populations but can occur in adults, can cause mechanical small bowel obstruction 1
Volvulus, including midgut volvulus showing "whirlpool sign" of twisted mesenteric vessels, can cause mechanical small bowel obstruction 4
Colorectal malignancy is the most common cause of colonic obstruction 5
Diverticular stricture, volvulus, and fecal impaction can also cause mechanical large bowel obstruction 5

The World Journal of Emergency Surgery recommends immediate surgical intervention for closed-loop obstruction, bowel ischemia, portal venous gas, free intraperitoneal air, and "whirlpool sign" indicating volvulus 1, 2, 3, 4, 9

The American College of Radiology recommends examining for peritonitis, checking all hernial orifices and previous surgical scars, assessing vital signs, and obtaining plain abdominal radiograph only if CT is unavailable 1, 3, 5
CT scan with IV contrast has over 90% accuracy for diagnosing obstruction and identifying the cause, and multiplanar reformations significantly improve detection of transition points 1, 2, 5
The World Journal of Emergency Surgery recommends looking for transition point, assessing for "small bowel feces sign" and "beak sign" at transition point, and evaluating bowel wall enhancement 1, 5

The Gastroenterology society recommends colonoscopy to terminal ileum and small bowel imaging to define disease extent in patients with inflammatory bowel disease 6, 10
The World Journal of Emergency Surgery recommends considering internal hernias through mesenteric defects in patients with a history of bariatric surgery, and using MRI in pregnant patients to avoid radiation 4

The American College of Radiology recommends not delaying CT scan, as plain radiographs are often nonspecific and prolong evaluation 1
The World Journal of Emergency Surgery recommends not giving oral contrast before gastric decompression, as it risks aspiration pneumonia, and not waiting beyond 72 hours for non-operative management without clear improvement 2, 3