Fluid filled small bowel loops on CT scan is a very common and frequently normal finding. By itself, this means nothing that is significant. Even in the setting of abdominal pain or other symptoms, this finding by itself is not clinically significant. It becomes significant when there are other associated findings which can indicate more severe disease.
Normally small bowel loops, that is the portion of the bowel between the stomach and colon, are either filled with fluid, gas, or both. The wall is usually very smooth and thin, and the small bowel usually is distributed evenly throughout the abdomen. There is normally fluid in small bowel loops.
I see some radiologists call fluid filled small bowel loops as possible enteritis. While this is true and it’s possible based on what the symptoms are, I usually reserve that diagnosis for bowel which is thickened or inflamed. The diagnosis of enteritis may be present anyways, but this can be made on clinical grounds.
Fluid filled small bowel loops are more concerning when they are thickened or dilated. Thickened small bowel loops may indicate enteritis or inflamed bowel. Dilated fluid filled small bowel loops may indicate a bowel obstruction or ileus. An ileus is when the small bowel bowel is kind of paralyzed and not working the way it should. In bowel obstruction, the classic finding is an abrupt transition from dilated to normal bowel. This is usually accompanied by abdominal pain, nausea and vomiting.
Fluid filled small bowel which is dilated can also be normal in some cases. Therefore it is very important that the referring clinical doctor use his clinical judgement in determining the most appropriate diagnosis. It is important to treat the patient and not the imaging finding.
In cases where the diagnosis is not clear, a contrast agent is administered to the patient by mouth. X-rays are taken and the contrast is followed over time in the small bowel. The idea being that the contrast will not make its way to the colon in a reasonable time in an obstructed bowel. The contrast that the patient drank will make it to the colon if the small bowel is simply fluid filled and not obstructed. A surgeon may also be consulted to manage the case if obstruction is suspected.