The diagnosis and treatment of intestinal ischemia varies somewhat depending on the particular patient, suspected source, and clinical situation. What is consistent and clear, however, is that early diagnosis is essential to improve the chances for a good outcome. In general, the longer the injury is sustained without treatment, the greater the chance that the damage done to the intestines will be irreversible.
The first considerations for a physician in diagnosing intestinal ischemia are the patient’s past medical history, his or her current symptoms, and results of a thorough physical examination. The diagnostic tools most commonly used to supplement this information include routine blood tests, colonoscopy, ultrasound, abdominal radiologic studies including CAT or MRI scans, mesenteric angiography, and exploratory abdominal surgery. Angiography is a special radiologic study of one’s blood vessels. Contrast material is injected through a small catheter placed into an abdominal artery or vein, after which radiologic images of the vessels are generated.
In acute small intestinal ischemia, particularly cases caused by arterial blockage, initial management of the patient includes addressing the relevant underlying and precipitating medical conditions, intravenous or “IV” fluids, and antibiotics to prevent possible infection. Angiography is considered the gold standard for diagnosis and is usually performed after a CT scan has shown that the abdominal pain is not caused by any other disorder that is mimicking intestinal ischemia. Sometimes a CT-angiogram, which is a non-invasive way of studying the intestine and its blood vessels, obviates the need for a formal angiographic study. Afterwards, a treatment decision is made based largely upon the findings on angiography and the physician’s assessment of the patient’s clinical status. If a significant embolus or thrombus is found in a blood vessel and the patient appears ill, a laparotomy (open abdominal surgery) or laparoscopy (exploration of the abdomen through an endoscopic tube inserted into the abdominal cavity) generally is recommended either to remove the obstruction in the blood vessel or to create a bypass route for blood around the blockage. If, at the time of surgery, the surgeon finds segments of the intestine that are necrotic, that portion of bowel is resected (removed), and the portions of the intestine above it and below are reconnected. A second operation may be performed within 24 hours to see if the now treated blood vessels have allowed previously injured portions of the intestine to recover. If so, there may be no need for further resection. Medication that dilates, or widens vessels in order to improve blood flow can be given via the arterial catheter put in place during angiography, usually prior to, but occasionally after, surgery.
When a venous obstruction is suspected, CT scan has been used successfully for diagnosis. Angiography can be used more selectively to aid in treatment of a particular vein. When patients are demonstrated to have a thrombus in a vein and are not considered to have signs of infarction, anticoagulant (“blood thinning”) drugs, and/or medication aimed toward dissolving the clot can be used. If a patient develops signs of more threatening ischemia, surgery is indicated to remove clots and any unsalvageable segments of the intestines, as discussed above.
In cases of non-occlusive intestinal ischemia, there is no identifiable point of blockage seen by angiography. Rather, the blockage is caused by diffuse spasm in the blood vessels supplying the intestines and the spasm is precipitated by underlying medical conditions such as heart failure, cardiac arrhythmias, and hypotension; these underlying conditions must be addressed to help restore blood delivery to the intestines. Patients with vasospasm may benefit from by administration of a vasodilator through a catheter directly placed in the main blood vessel supplying the intestine to break the spasm and thereby improve intestinal blood flow.
In colon ischemia, the extent and severity of the injury again dictates the action taken. If the patient is stable, colonoscopy is ideally performed within 24-48 hours of the onset of symptoms. Patients in this situation can expect to be placed on a restricted diet in the short-term, and given antibiotics to prevent serious infection. In most cases, symptoms abate within 1 to 2 days and the injury to the colon resolves in 1 to 2 weeks. A minority of patients develop more significant consequences and are treated accordingly, possibly with surgery.