Intestinal obstruction is a frequent cause of emergency room visits and represents about 4-7% of the causes of acute abdominal pain syndrome and up to 30% in adults over 60 years old.

Although 65 to 80% of patients are treated medically, small bowel obstruction remains a serious pathology, with a high mortality rate that can reach 25% in case of small bowel ischemia. It is necessary to systematically perform a CT scan in the initial workup of small bowel obstructions to confirm the diagnosis, identify the mechanism and detect signs of ischemia that would require emergency surgery.

The best sign for the diagnosis of ischemia is the defect or asymmetry of parietal enhancement of the dilated small bowel. In the literature, this sign is described almost exclusively at portal time. In case of suspicion of mesenteric ischemia (another serious pathology affecting the small bowel), it is recommended to perform an examination with three acquisitions (without injection, arterial time, and portal time).

The department's experience has shown that arterial time is sometimes more sensitive than portal time for visualizing a parietal enhancement defect of the small bowel in mechanical occlusions.

Very few studies have investigated the diagnostic performance of parietal enhancement asymmetry on arterial time in mechanical occlusions of the small bowel.

Inclusion Criteria:

• Patient whose age is ≥ 18 years
• Patient with a diagnosis of mechanical small bowel obstruction on CT performed between April 2014 and December 2019
• Patient who had a CT scan with at least 3 phases: injection-free, arterial time, portal time
• French-speaking patient

Exclusion Criteria:

• Patient who did not have surgery within the first 24 hours
• Patient with a history of abdomino-pelvic surgery in the month preceding the scan
• Patient under guardianship or curatorship
• Patient deprived of liberty
• Patient under court protection
• Patient who objects to the use of his or her data for this research

Patients, over 18 years of age, with a diagnosis of mechanical small bowel obstruction on CT and having had a CT scan with at least 3 phases: injection-free, arterial time, portal time, were managed at GHPSJ between April 2014 and December 2019