Ischemia means poor circulation that’s cutting off oxygen to the area. “Mesenteric Ischemic” refers to the circulation to the bowel (aka “mesentery”). If a part of the body doesn’t get enough oxygen, its tissue dies. If part of the bowel dies, it rots, and all the germs inside the bowel cause major infection (Peritonitis, Sepsis) that’s often fatal. Treatment is surgical, cutting out the dead part of the bowel. If this all sounds pretty grim, it is.
Ischemic Bowel occurs for the same reason ischemia can occur in the heart, brain, legs, & wherever — damaged arteries. The damage is from many years of Hypertension, smoking, Diabetes, high Cholesterol, and unlucky genetics. Sometimes it occurs if heart disease like Atrial Fibrillation causes a clot to form, which then breaks loose and flows downstream to obstruct an artery.
Abdominal pain from bowel ischemia often begins quickly, sometimes with nausea or vomiting. The main diagnostic clue is that the patient seems in a lot of pain, but the abdomen is not very tender to palpation (pressing on it). Patients are almost always older, and have many of the other conditions that lead to poor circulation. We’d never consider this diagnosis in a younger, healthier person.
Diagnosis can be very difficult. It’s made by CT- or MR-angiogram — CT scan or MRI done with injection of dye, timed specially to catch the dye as it flows through bowel arteries and veins. One mistake would be to give the patient dye to swallow orally as well. This makes it easier to find various other abdominal diseases (like appendicitis, etc.), but will get in the way of seeing bowel ischemia. So if bowel ischemia is at all a possibility, the scan with oral dye should be done later if necessary.
Unfortunately, the CT- or MR-angiogram may miss many cases (false-negative). The most definite test for bowel ischemia is a CT-arteriogram, injecting dye directly into a artery, but it carries risk of worsening the illness.
Treatment is likewise difficult. There are ways to try to break up clots in the bowel arteries, but some methods carry their own dangers. The main therapy, anticoagulants, hopes to keep the clot from extending, until the body can resolve it on its own. If bowel dies, surgeons remove segments.
If this seems unappetizing, it’s a good reason to stop smoking and control diseases that contribute to ischemia in the first place.