First of all, to determine the presence of intestinal obstruction, the diagnostic criteria are: fluid or gas accumulation in the intestinal canal, dilated small intestine inner diameter more than 3cm; colon inner diameter more than 6cm, that is, the diagnosis of dilated intestine. Mechanical intestinal obstruction has the “migrating band sign” at the junction of dilated intestine and depressed intestine; paralytic intestinal obstruction often manifests as dilated pneumatization and fluid accumulation in both small intestine and colon, while pneumatization is often the main cause, and there is no obvious “migrating band sign”, and the intestinal paralysis is often seen. In addition to the dilatation of the corresponding intestine supplied by the infarcted or embolized vessels, high-density thrombus or intravascular filling defect can be seen in the corresponding vessels of the obstructed intestine on the enhancement scan.
Factors affecting the accuracy of CT diagnosis of intestinal obstruction include: limited intestinal dilatation caused by food debris in the colon at the ileocecal valve, which may be misdiagnosed as intestinal obstruction; mild partial intestinal obstruction is missed because the migrating zone is not shown; paralytic intestinal obstruction is dilated in the ascending and transverse colon while the descending colon is depressed and misdiagnosed as mechanical intestinal obstruction; other factors and technical factors cause it.
CT can also show the signs of intestinal lumen, intestinal wall, intestinal canal and organ changes in mesentery and abdominal cavity after intestinal obstruction, and recognizing these signs is beneficial to the correct diagnosis and prognosis of intestinal obstruction.