Colon and small intestine
Colon and small intestine
The small intestine and colon are parts of your digestive tract, which processes the foods you eat. The intestines take nutrients from the foods. What isn't absorbed by the intestines continues along the digestive tract and is passed as stool during a bowel movement.
Intestinal ischemia (is-KEE-me-uh) describes a variety of conditions that occur when blood flow to your intestines decreases. Ischemia can be due to a fully or partially blocked blood vessel, usually an artery, or low blood pressure leading to an overall reduced blood flow. Intestinal ischemia can affect your small intestine, your large intestine (colon) or both.
The decreased blood flow doesn't provide enough oxygen for the cells in your digestive system. Intestinal ischemia is a serious condition that can cause pain and make it difficult for your intestines to work properly. In severe cases, loss of blood flow to the intestines can damage intestinal tissue and possibly lead to death.
Treatments are available for intestinal ischemia. To improve the chances of recovery, it's crucial to recognize the early symptoms and get medical help right away.
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Signs and symptoms of intestinal ischemia can develop suddenly (acute) or gradually (chronic). Signs and symptoms may be different from one person to the next, but there are some generally recognized patterns that suggest intestinal ischemia.
Symptoms of sudden (acute) intestinal ischemia
Signs and symptoms of acute intestinal ischemia typically include:
- Sudden belly (abdominal) pain that may be mild, moderate or severe
- An urgent need to have a bowel movement
- Frequent, forceful bowel movements
- Abdominal tenderness or bloating (distention)
- Blood in your stool
- Nausea and vomiting
- Mental confusion in older adults
Symptoms of gradually developing (chronic) intestinal ischemia
Signs and symptoms of chronic intestinal ischemia can include:
- Abdominal cramps or fullness, usually within 30 minutes after eating, and lasting 1 to 3 hours
- Abdominal pain that gets gradually worse over weeks or months
- Fear of eating because of pain that happens after eating
- Unintended weight loss
- Nausea and vomiting
When to see a doctor
Seek immediate medical care if you have sudden, severe abdominal pain. Pain that makes you so uncomfortable that you can't sit still or find a comfortable position is a medical emergency.
If you have other signs or symptoms that worry you, make an appointment with your health care provider.
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Intestinal ischemia occurs when the blood flow through the major blood vessels that supply blood to (arteries) and from (veins) your intestines slows or stops. The condition has many possible causes. These can include:
- Blockage in an artery caused by a blood clot
- Narrowing of an artery due to buildup of fatty deposits, such as cholesterol (atherosclerosis)
- Low blood pressure leading to an overall reduced blood flow
- Blockage in a vein, less commonly
Intestinal ischemia is often divided into categories. Colon ischemia (ischemic colitis) affects the large intestine. Types of ischemia that affect the small intestine include acute mesenteric ischemia, chronic mesenteric ischemia and ischemia due to mesenteric venous thrombosis.
Colon ischemia (ischemic colitis)
This type of intestinal ischemia, which is the most common, occurs when blood flow to part of the colon is slowed or blocked. The cause of reduced blood flow to the colon isn't always clear, but a number of conditions can put you at risk of colon ischemia:
- Dangerously low blood pressure (hypotension) related to dehydration, heart failure, major surgery, trauma or shock
- A blood clot or severe atherosclerosis in an artery supplying the colon
- Twisting of the bowel (volvulus) or trapping of intestinal contents within a hernia
- Excessive bowel enlargement from bowel blockage caused by scar tissue or a tumor
- Other medical disorders that affect your blood, such as inflammation of your blood vessels (vasculitis), lupus or sickle cell anemia
- Medications that narrow (constrict) blood vessels, such as some used to treat heart disease and migraine
- Hormonal medications, such as birth control pills
- Cocaine or methamphetamine use
- Vigorous exercise, such as long-distance running
Acute mesenteric ischemia
Mesenteric ischemia occurs when narrowed or blocked arteries restrict blood flow to your small intestine. Decreased blood flow can permanently damage the small intestine.
Acute mesenteric ischemia is the result of a sudden loss of blood flow to the small intestine. It may be due to:
- A blood clot (embolus) that comes loose from your heart and travels through your bloodstream to block an artery. It usually blocks the superior mesenteric artery, which supplies oxygen-rich blood to your intestines. This is the most common cause of acute mesenteric artery ischemia. This type can be brought on by congestive heart failure, an irregular heartbeat (arrhythmia) or a heart attack.
- A blockage that develops within one of the main intestinal arteries and slows or stops blood flow. This often is a result of atherosclerosis. This type of sudden ischemia tends to occur in people with chronic intestinal ischemia.
- Impaired blood flow resulting from low blood pressure due to shock, heart failure, certain medications or chronic kidney failure. This is more common in people who have other serious illnesses and who have some degree of atherosclerosis. This type of acute mesenteric ischemia is often referred to as nonocclusive ischemia, which means that it's not due to a blockage in the artery.
Chronic mesenteric ischemia
Chronic mesenteric ischemia results from the buildup of fatty deposits on an artery wall (atherosclerosis). The disease process is generally gradual. It's also known as intestinal angina because it results in decreased blood flow to the intestines after eating. You may not require treatment until at least two of the three major arteries supplying your intestines become severely narrowed or completely blocked.
A possibly dangerous complication of chronic mesenteric ischemia is developing a blood clot within a narrowed artery. This can cause blood flow to be suddenly blocked, resulting in acute mesenteric ischemia.
Ischemia due to mesenteric venous thrombosis
This ischemia occurs when blood can't leave your small intestines. A blood clot can develop in a vein draining blood from your intestines. Veins carry blood that has had the oxygen removed back to the heart. When the vein is blocked, blood backs up in the intestines, causing swelling and bleeding. This may result from:
- Acute or chronic irritation and swelling (inflammation) of your pancreas (pancreatitis)
- Infection inside your belly (abdominal infection)
- Cancers of the digestive system
- Bowel diseases, such as ulcerative colitis, Crohn's disease or diverticulitis
- Disorders that make your blood more prone to clotting (hypercoagulation disorders), such as an inherited clotting disorder
- Medications such as estrogen that can increase clotting risk
- Abdominal injuries
Factors that may increase your risk of intestinal ischemia include:
- Buildup of fatty deposits in your arteries (atherosclerosis). If you've had other conditions caused by atherosclerosis you have an increased risk of intestinal ischemia. These conditions include decreased blood flow to your heart (coronary artery disease), legs (peripheral vascular disease) or the arteries supplying your brain (carotid artery disease).
- Age. People older than 50 are more likely to develop intestinal ischemia.
- Smoking. Cigarettes and other forms of smoked tobacco increase your risk of intestinal ischemia.
- Heart and blood vessel problems. Your risk of intestinal ischemia is increased if you have congestive heart failure or an irregular heartbeat such as atrial fibrillation. Blood vessel diseases that result in irritation and inflammation of veins and arteries (vasculitis) may also increase risk.
- Medications. Certain medications may increase your risk of intestinal ischemia. Examples include birth control pills and medications that cause your blood vessels to expand or contract, such as some allergy medications and migraine medications.
- Blood-clotting problems. Diseases and conditions that increase your risk of blood clots may increase your risk of intestinal ischemia. Examples include sickle cell anemia and the Factor V Leiden mutation.
- Other health conditions. For example, having high blood pressure, diabetes or high cholesterol can increase the risk of intestinal ischemia.
- Recreational drug use. Cocaine and methamphetamine use have been linked to intestinal ischemia.
Complications of intestinal ischemia can include:
- Death of intestinal tissue. If blood flow to your intestine is completely and suddenly blocked, intestinal tissue can die (gangrene).
- A hole through the wall of the intestines (perforation). A perforation can develop, which can cause the contents of the intestine to leak into the abdominal cavity. This may cause a serious infection (peritonitis).
- Scarring or narrowing of your intestine. Sometimes the intestines can recover from ischemia, but as part of the healing process the body forms scar tissue that narrows or blocks the intestines. This occurs most often in the colon. Rarely this happens in the small intestines.
Other health conditions, such as chronic obstructive pulmonary disease (COPD), can worsen the severity of intestinal ischemia. Emphysema, a type of COPD, and other smoking-related lung diseases increase this risk.
In some cases, intestinal ischemia can result in death.
By Mayo Clinic Staff
Aug. 12, 2022