What is abdominal stranding?

Abdominal Stranding: Definition and Clinical Significance

Abdominal stranding (also called "fat stranding" or "mesenteric stranding") is a CT finding that appears as abnormally increased attenuation (hazy increased density) in the fat tissue of the abdomen or mesentery, representing inflammatory changes, edema, or regional free fluid. 1, 2

Radiological Appearance

• On CT imaging, fat stranding appears as hazy increased density in the normally dark (low-attenuation) fat tissue 2
• On MRI, it shows high T2 signal intensity, particularly on fat-suppressed sequences 1, 2
• Best visualized on contrast-enhanced CT, as non-contrast CT has lower sensitivity for detecting subtle fat stranding 2, 3

Clinical Significance and Interpretation

Fat stranding is a highly sensitive but non-specific finding that serves as a clue to identify the source of underlying inflammation or pathology. 2, 4

Key Diagnostic Principle: Disproportionate Fat Stranding

When fat stranding is disproportionately more severe than the degree of bowel wall thickening present, this suggests a narrower differential diagnosis centered in the mesentery rather than the bowel itself. 5, 6

This pattern specifically suggests:

• Diverticulitis (with mild, smooth bowel wall thickening and no lymphadenopathy) 5
• Epiploic appendagitis (with central high attenuation areas and hyperattenuated rim, adjacent to colon) 5
• Omental infarction (always centered in the omentum) 7, 5
• Appendicitis (with dilated, fluid-filled appendix as most specific finding) 5

Common Clinical Contexts

In Trauma Settings

Mesenteric stranding has 34% sensitivity and 92% specificity for bowel injury in blunt abdominal trauma, making it one of the more sensitive CT signs alongside bowel wall thickening. 8, 1

• Should prompt consideration of bowel injury when combined with other findings (free fluid without solid organ injury, bowel wall abnormalities) 8
• Four or more CT findings including mesenteric stranding are pathognomonic for bowel injury requiring surgical treatment 8

In Inflammatory Conditions

Fat stranding indicates active inflammation in multiple conditions:

• Diverticulitis: Pericolonic fat stranding is a characteristic finding with 98% diagnostic accuracy when combined with bowel wall thickening and diverticula 3
• Inflammatory bowel disease: Mesenteric fat stranding indicates active inflammation and more severe disease 1
• Gastritis/peptic ulcer disease: Fat stranding along the gastroduodenal region suggests inflammation or perforation 8
• Cholecystitis: Perivesicular fat stranding indicates active gallbladder inflammation 2

In Infectious/Ischemic Conditions

• Necrotizing fasciitis: Fat stranding with skin thickening and fluid/gas in fascial planes 2
• Mesenteric ischemia: Associated with fat stranding in the affected mesenteric region 1

Important Distinction: Stranding vs. Thickening

Fat stranding must be distinguished from fat thickening ("creeping fat" or "fibrofatty proliferation"):

• Stranding = increased attenuation representing acute inflammation/edema 1, 2
• Thickening = increased volume of fat that displaces bowel loops, representing a chronic process (particularly in Crohn's disease) 1

Clinical Pitfalls and Caveats

• Fat stranding is non-specific and can be associated with conditions ranging from benign to life-threatening, so it must be interpreted in clinical context 4
• Does not provide a final diagnosis but directs attention to an area of concern requiring further evaluation 4
• Contrast-enhanced CT is superior to non-contrast CT for detecting subtle fat stranding and associated complications 2, 3
• In trauma patients with equivocal CT findings including mesenteric stranding, serial clinical examinations and repeat CT at 6 hours should be considered 8