Ischemic colitis natural history

Overview
Ischemic colitis can span a wide spectrum of severity; most patients are treated supportively and recover fully, while a minority with very severe ischemia may develop sepsis and become critically ill. Most patients make a full recovery; occasionally, after severe ischemia, patients may develop long-term complications such as a stricture or chronic colitis.

Natural History
Three progressive phases of ischemic colitis have been described:


 * A hyperactive phase occurs first, in which the primary symptoms are severe abdominal pain and the passage of bloody stools. Many patients get better and do not progress beyond this phase.


 * A paralytic phase can follow if ischemia continues; in this phase, the abdominal pain becomes more widespread, the belly becomes more tender to the touch, and bowel motility decreases, resulting in abdominal bloating, no further bloody stools, and absent bowel sounds on exam.


 * Finally, a shock phase can develop as fluids start to leak through the damaged colon lining. This can result in shock and metabolic acidosis with dehydration, low blood pressure, rapid heart rate, and confusion. Patients who progress to this phase are often critically ill and require intensive care.

Prognosis
Most patients with ischemic colitis recovery fully, although the prognosis depends on the severity of the ischemia. Patients with pre-existing peripheral vascular disease or ischemia of the ascending (right) colon may be at increased risk for complications or death.

Non-gangrenous ischemic colitis, which comprises the vast majority of cases, is associated with a mortality rate of approximately 6%. However, the minority of patients who develop gangrene as a result of colonic ischemia have a mortality rate of 50-75% with surgical treatment; the mortality rate is almost 100% without surgical intervention.

Long-term complications
About 20% of patients with acute ischemic colitis may develop a long-term complication known as chronic ischemic colitis. Symptoms can include recurrent infections, bloody diarrhea, weight loss, and chronic abdominal pain. Chronic ischemic colitis is often treated with surgical removal of the chronically diseased portion of the bowel.

A colonic stricture is a band of scar tissue which forms as a result of the ischemic injury and narrows the lumen of the colon. Strictures are often treated observantly; they may heal spontaneously over 12-24 months. If a bowel obstruction develops as a result of the stricture, surgical resection is the usual treatment, although endoscopic dilatation and stenting have also been employed.