Ischemic colitis is inflammation of the large intestine caused by insufficient oxygen supply to the intestinal wall. The inflammation usually affects only a certain segment of the intestine, typically its left part.
The condition is caused by hypoperfusion of the large intestine. It may be result of a drop of the blood pressure in the whole body (shock states, extensive surgical interventions, heart failure, severe dehydration, effect of certain medications, etc.) or disorders of blood vessels nourishing the intestine. The blood flow may be disrupted by closure of large intestinal arteries described in chapter about the vascular ileus. Closure of small arteries can occur in some autoimmune diseases (systemic lupus erythematosus), in chronic diabetes, in diseases associated with increased blood clotting (e.g. factor V Leiden mutation) and in woman using hormonal contraception. In many cases, the cause of ischemic colitis is unclear.
The symptoms depend on the extent, speed and duration time of the hypoperfusion. The condition typically manifests with acute abdominal pain, nausea and vomiting. There is often a sudden urge to defecate, diarrhea and presence of red blood in the stool. Severe forms of the ischemic colitis are followed by development of toxic megacolon and vascular ileus. The intestinal barrier is disrupted thus allowing the bacteria to penetrate into the abdominal cavity causing peritonitis and sepsis. The result is a shock condition and death. Milder forms can have only minor symptoms but no matter the severity of acute ischemic colitis, there may be always present late complications such as intestinal strictures.
In addition to medical history and cautious physical examination of the abdomen, it is important to do the abdominal X-ray to confirm findings typical for ileus. Findings in ultrasound or computed tomography may be indeterminate. Examination of the large intestine with a contrast agent (bowel enema) may show typical finding of multiple narrowed areas. The best diagnostic method, however, is the colonoscopy. It allows to visualize the damage and mucosal changes of a section of the large intestine and to take samples for histological examination. When there is a suspicion of a large artery closure, the best method is the angiography.
In mild forms of the disease the treatment is conservative. We have to avoid low blood pressure and dehydration. We usually administer antibiotics as a supportive therapy to prevent infectious complications. Large arterial closures can be solved by an endovascular (therapeutic angiography) or surgical approach. If the ischemia caused necrosis of the intestine, it is necessary to surgically remove the necrotic part.