Intestinal Ischaemia

Intestinal ischaemia is a serious medical condition that occurs when blood flow to the intestines becomes reduced or blocked, depriving these organs of the oxygen they need to function properly. Though uncommon, this condition can be life-threatening if not treated quickly.

Table of contents

• What is intestinal ischaemia?
• Types of intestinal ischaemia
• Affected parts of the body
• What causes intestinal ischaemia?
• Who is at risk?
• Signs and symptoms
• How the condition affects the body
• How is it diagnosed?
• Treatment options
• Outlook and complications

What is intestinal ischaemia?

Intestinal ischaemia refers to a range of conditions that happen when blood flow to the intestines slows or stops. Ischaemia means that parts of the body are not getting enough blood flow. When this affects the intestines, too little oxygen reaches the cells in the digestive system, which is the system through which food travels in the body.^[1]

This is an uncommon medical condition, but it has a very high death rate. The condition affects about 5 per 100,000 people per year in developed countries for the acute form, and about 1 per 100,000 for the chronic form.^[4] Even with treatment, the risk of death ranges from 60% to 100%, depending on the cause of the blockage.^[2]

Ischaemia can happen because a blood vessel becomes fully or partly blocked, most often an artery. It can also result from low blood pressure, which leads to less blood flow to the intestines. In severe cases, loss of blood flow can cause the intestines to become permanently damaged or even die, which may lead to death.^[1]

• Small intestine
• Large intestine (colon)
• Mesentery
• Superior mesenteric artery
• Inferior mesenteric artery

mesenteric ischaemia, bowel ischaemia, ischaemic colitis, ischaemic bowel disease

Types of intestinal ischaemia

There are two main types of intestinal ischaemia, based on how quickly symptoms appear.^[1]

Acute intestinal ischaemia occurs when symptoms come on quickly and suddenly. This type of ischaemia is similar to what happens during a heart attack or stroke, where a blood clot suddenly blocks blood flow. The most common symptom is sudden, severe belly pain. This form is a medical emergency that needs immediate care.^[1][3]

Chronic intestinal ischaemia develops when symptoms come on slowly over time. This type usually happens because the arteries that supply blood to the intestines start to narrow gradually, often from a buildup of fatty deposits called plaque. The condition takes longer to develop, and symptoms usually get worse over time.^[1][3]

The condition can also be classified based on which part of the intestine is affected. When it affects the small intestine, it is commonly called mesenteric ischaemia. When it affects the large intestine, it is generally referred to as colonic ischaemia or ischaemic colitis.^[2]

Affected parts of the body

The intestine receives blood mainly from two major arteries. The superior mesenteric artery supplies blood to the bowel from the lower part of the small intestine to two-thirds of the large intestine. The inferior mesenteric artery supplies blood to the remaining one-third of the large intestine down to the rectum.^[2]

There are two areas in the colon that are especially prone to ischaemia. These are called watershed areas, which are regions between two major arteries. One area is the splenic flexure, and the other is the rectosigmoid junction. In about half of people, the arteries supplying these areas are poorly developed. These watershed areas account for about 70% of ischaemic colitis cases.^[2]

The mesentery is an organ in the belly that holds several other organs in place, including the small and large intestines and colon. The mesentery also contains a network of blood vessels that supply these organs. When ischaemia affects this area, it means that the lack of blood flow is affecting the mesentery and the organs it supports.^[3]

What causes intestinal ischaemia?

Intestinal ischaemia occurs when blood flowing through the major arteries that supply the intestines slows or stops. There are several possible causes.^[5]

A blood clot can block one of the arteries supplying the intestine. This can happen when a clot forms somewhere else in the body and travels to the intestine, or when a new clot forms directly in the intestinal artery. People who have had a heart attack or who have irregular heart rhythms, such as atrial fibrillation, are at higher risk for this type of blockage.^[5]

The arteries that supply blood to the intestine may become narrowed or blocked from a buildup of cholesterol and fatty deposits. This is the same process that causes heart attacks when it happens in arteries to the heart.^[5]

The veins carrying blood away from the intestine may become blocked by blood clots. This blocks blood flow in the intestine. This is more common in people with liver disease, cancer, or conditions that make blood clot too easily.^[5]

Very low blood pressure in people who already have narrowing of the intestinal arteries may also cause loss of blood flow to the intestine. This often happens in people with other serious medical problems.^[5]

Other causes include a hernia, where the intestine moves into the wrong place or becomes tangled, cutting off blood flow. The intestine may also become trapped in scar tissue from past surgery, which can lead to loss of blood flow if left untreated.^[5]

Who is at risk?

Intestinal ischaemia is more common as people age. It most often affects people over 60 years old. Rates are about equal in males and females of the same age.^[4][3]

The condition usually happens along with heart and circulation conditions, especially ones that can cause blood clots. Risk factors include:^[3][4]

• Atrial fibrillation, which is a type of irregular heart rhythm
• Heart failure
• Previous heart attack
• Coronary artery disease
• Structural heart defects
• High blood pressure
• High cholesterol
• Diabetes
• Chronic kidney failure
• Conditions that make blood clot too easily
• Peripheral vascular diseases, such as peripheral artery disease
• History of blood vessel inflammation
• Recent cardiovascular surgery
• Recent surgery
• Tobacco use, past or present
• Use of certain medications that constrict blood vessels
• Use of drugs such as cocaine or methamphetamine

Signs and symptoms

Symptoms may differ from person to person and depend on whether the condition is acute or chronic.^[1]

The most common symptom of acute intestinal ischaemia is sudden, severe belly pain. The pain is often described as being out of proportion to what a doctor can find during a physical examination. Other symptoms of acute ischaemia include:^[1]

• An urgent need to pass stool
• Forceful bowel movements
• Blood in the stool
• Diarrhoea
• Fever
• Vomiting
• Belly tenderness
• Mental confusion, particularly in older adults

Only one-third of patients present with the classic combination of belly pain, fever, and blood in the stool.^[15]

Symptoms of chronic intestinal ischaemia may include:^[1]

• Belly cramps or pain after eating, often starting 15 to 30 minutes after a meal and lasting up to 4 hours
• Fear of eating because of pain that follows
• Unintended weight loss
• Diarrhoea or constipation
• Nausea and vomiting
• Bloating
• Early feeling of fullness when eating

The belly pain that occurs after eating in chronic cases is sometimes called abdominal angina. This pain often leads to a fear of eating, which results in significant weight loss.^[1]

How the condition affects the body

All cells, tissues, and organs in the body need a steady supply of blood and oxygen. Without that supply, they start to die. What makes intestinal ischaemia so dangerous is that it affects the intestines, which contain trillions of bacteria.^[3]

Normally, these bacteria are helpful and aid in digesting food. But when the intestines start to die, those bacteria can spread to places they do not belong and cause dangerous infections. This can lead to sepsis, a life-threatening condition that happens when the immune system’s overwhelming reaction to an infection ends up damaging the body as well.^[3]

Intestinal ischaemia occurs when at least a 75% reduction in intestinal blood flow lasts for more than 12 hours. Less blood flow means that too little oxygen goes to the cells in the digestive system. In severe cases, this can cause parts of the intestines to develop ulcers, bleed internally, or die completely. When intestinal tissue dies, this is called intestinal necrosis or bowel gangrene.^[2]

How is it diagnosed?

Diagnosing intestinal ischaemia can be challenging because various other conditions have similar symptoms. If a healthcare professional suspects intestinal ischaemia after a physical exam, several diagnostic tests may be ordered based on symptoms.^[6]

Blood tests may be done, though blood tests alone cannot diagnose intestinal ischaemia. Certain blood test results might suggest the condition. For example, a high white blood cell count can be a marker of infection. Blood tests may also show increased acid in the bloodstream, called lactic acidosis.^[6][5]

Imaging tests let healthcare professionals see internal organs and rule out other causes of symptoms. Imaging tests may include an X-ray, an ultrasound, a CT scan (computed tomography), or an MRI (magnetic resonance imaging). To look at blood flow in veins and arteries, a special type of CT scan or MRI called an angiogram may be used.^[6]

A scope may be used to see inside the digestive tract. This involves putting a lighted, flexible tube with a camera on its tip into the rectum to view the digestive tract. The scope can look at the last 2 feet of the colon, which is called sigmoidoscopy. When the test looks at the whole colon, it is called colonoscopy. The scope may also be inserted into the mouth to examine the upper portion of the small intestine, which is called endoscopy.^[6]

Angiography is a test in which a long, thin tube called a catheter is inserted into an artery in the groin or arm. A dye is injected through the catheter and flows to the intestinal arteries. The dye moving through the arteries allows narrowed areas or blockages to show up on X-rays. Angiography is considered the best method of diagnosis when available. Angiography also lets a healthcare professional treat a blockage during the same procedure by removing a clot, administering medicine, or using special tools to widen an artery.^[6][4]

In some cases, surgery may be needed to find and remove damaged tissue. Opening the belly allows diagnosis and treatment during one procedure. Sometimes, surgery is the only way to detect intestinal ischaemia.^[6][5]

Treatment options

Treatment depends on the severity of symptoms and whether the condition is acute or chronic. Getting medical help early improves the chances of recovery.^[1]

For acute intestinal ischaemia, immediate treatment is crucial. In most cases, the condition needs to be treated with surgery. The section of intestine that has died is removed, and the healthy remaining ends of the bowel are reconnected. In some cases, a temporary or permanent opening in the abdomen, called a jejunostomy or ileostomy, may be needed.^[5]

If arteries are narrowed but not totally blocked, an angioplasty and stent procedure may be performed to reopen the artery and allow blood to flow properly again. During this procedure, special tools are used to widen the artery, and a small tube called a stent may be placed to keep the artery open.^[5]

Treatment may also include medications to break down blood clots, which can be delivered at the site of obstruction. These are called thrombolytics. Blood thinners such as heparin or warfarin may be given to prevent future blockages.^[5]

In people with chronic ischaemia, bypass surgery may be the treatment of choice. This creates a new route for blood to flow around the blocked area.^[4]

Additional treatment may include:^[5]

• Broad-spectrum antibiotics to treat or prevent infections
• Pain medications
• Medications to widen blood vessels
• Intravenous fluids for hydration and nourishment
• Bowel rest, meaning no food or liquids by mouth

After surgery, a doctor may not allow foods or liquids by mouth initially, and the person may receive nutrients through an intravenous tube. This is called bowel rest and can last from a few days to several weeks. During recovery, a liquid diet may be suggested.^[5]

The blockage of arteries to the intestine should be corrected if possible. A procedure called a second-look operation may be needed if bowel of questionable health was not removed during the first surgery.^[5]

Outlook and complications

Intestinal ischaemia is often deadly, so quick diagnosis and treatment are very important. If not rapidly treated, outcomes are often poor. Among those affected, even with treatment, the risk of death is 70% to 90% for acute cases.^[3] The successful outcome depends upon having a high level of suspicion and prompt management.^[2]

The outlook depends on the cause of the ischaemia. Prompt treatment can lead to a good outcome. However, damage or death of the bowel tissue is a serious condition that can result in death if not treated right away.^[5]

Possible complications include:^[5]

• Irreversible damage to the bowels
• Death of bowel tissue
• Peritonitis, which is a serious infection in the belly
• Sepsis and blood infections
• Failure of other organs
• Stricture formation, where the intestine becomes narrowed
• Short bowel syndrome
• Problems absorbing nutrients
• Dependence on nutrition through the veins
• Malnutrition

People who have a large amount of tissue death in the intestine can have problems absorbing nutrients. They may become dependent on getting nutrition through their veins.^[5]

Long-term complications depend on the location and nature of the underlying problem. Some people may develop strictures or scar tissue in the bowel. Others may experience chronic pain or fear of eating that leads to malnutrition.^[5]

Preventive measures include controlling risk factors such as irregular heartbeat, high blood pressure, and high cholesterol. Not smoking, eating a nutritious diet, and quickly treating hernias can also help prevent the condition.^[5]

It is important to contact a healthcare provider immediately if severe belly pain develops, especially if it comes on suddenly or occurs regularly after eating.^[5]