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Acute mesenteric ischemia is sudden blockage of blood flow to part of the intestines, which may lead to gangrene and perforation (puncture).
Acute mesenteric ischemia has several causes. It can be caused by an arterial embolism, which is a blood clot or piece of atherosclerotic plaque material (the buildup of cholesterol and other fatty materials in an artery) that travels from its origin in the heart or aorta to lodge in the smaller arteries (in this case those of the intestines). Another cause is a blood clot that forms spontaneously in the arteries or veins of the intestines, blocking flow. Sometimes flow is not blocked completely but is simply too low because of low heart output (as in heart failure or shock—see Shock) or because certain drugs (such as cocaine) narrow the blood vessels. In general, people older than 50 years are at greatest risk.
Blockage of blood flow for more than 10 to 12 hours causes the affected area of intestine to die, allowing intestinal bacteria to invade the person's system. Shock, organ failure, and death are likely if intestinal death occurs.
Symptoms
At first, the person has severe abdominal pain, usually developing suddenly, but the abdomen is only slightly tender when the doctor presses it. Pain out of proportion to tenderness is an important clue for the doctor. Later, as the intestine starts to die, the person's abdomen becomes tender to the touch.
Diagnosis and Treatment
If the doctor can make the diagnosis early, people usually recover well. If the diagnosis is not made until some of the affected intestine has died, 70 to 90% of people die. If the person has typical symptoms and the abdomen is very tender, doctors usually take the person right to surgery. At surgery, the blood vessel blockage can sometimes be removed or bypassed but sometimes the affected intestine must be removed. If the symptoms suggest acute ischemia but the abdomen is not tender, doctors may perform angiography, in which they thread a small catheter through the artery in the groin and into the arteries of the intestines and inject a contrast agent that outlines the blood vessels. If a blockage is seen, sometimes it can be opened by injecting certain drugs—if not, the person needs surgery. After recovery, many people need to take a drug to help prevent blood clotting. A person cannot survive if almost all the small intestine dies or is removed.
Last full review/revision October 2012 by Parswa Ansari, MD
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