Ischemic Colitis on X-ray

Ischemic colitis means that the colon is inflamed because of diminished blood flow.   It is more common in older individuals.  Patients can present with abdominal pain and bloody stools.  Abdominal X-rays can be one of the first imaging tests done.

What causes ischemic colitis?

Ischemic colitis is caused by arterial or venous blockage from various causes.  Hardening of the arteries from atherosclerosis is a common cause.  The condition can also result from low blood pressure or generalized low flow to the colon from poor heart function.  Inflammatory conditions of the blood vessels called vasculitis can also be a cause.

Is the entire colon involved with ischemic colitis?

The location of ischemic colitis depends on the cause.  Generally the location from a blockage of the superior mesenteric artery is from the cecum to the splenic flexure which is the part of the colon in the left upper abdomen.  The cause from a blockage of the inferior mesenteric artery is from the splenic flexure to the rectum.  These arteries feed those parts of the colon.

The location from a generalized decrease in blood flow will be in between those areas covered called watershed areas.  The splenic flexure of the colon and the junction of the sigmoid colon and rectum.

What do X-rays of the abdomen show in ischemic colitis?

X-rays of the abdomen may show no abnormality in some cases.  Cases where abnormality is seen may show dilated gas filled colon.  The decreased blood flow causes ileus or a paralysis of the colon.  The wall of the colon may become thickened from fluid.  This is called thumb printing.

Gas may form in the wall of the colon called pneumatosis.   Gas may form in the veins draining the colon.  Gas can go all the way to the liver.  If the bowel becomes perforated, then we will see free air in the peritoneal cavity of the abdomen.  There may be free fluid in the abdomen called ascites.

Ischemic colitis can be reversible or irreversible.  Some patients completely recover while others develop chronic colitis and strictures or narrowing of the colon.  Some go on to perforate their bowel.

It is a potentially life threatening condition and needs to be recognized promptly.  Blood vessel blockages may be treated with blood thinners or specially trained radiologists who will treat the blockage locally. Surgery may be needed if there is blood infection, bleeding, or perforation of the bowel.

Some findings of colitis from ischemia can be identified on X-rays.  The clinical findings always have to be put together with the X-ray findings.   We can sometimes see thickened colon, air in the wall of the colon, gas in the liver and free air on the abdomen from perforation.

CT will usually follow if there is clinical concern for ischemic colitis or if there are abnormal findings on X-ray.   It is important to remember that X-rays can be normal in this condition and that clinical doctors need to be alert to the possibility.   Specialty consultation may be needed to include gastroenterologists and surgeons.