Mesenteric ischemia, or small bowel ischemia, involves a blockage of blood flow to the small intestine. Symptoms include pain and bloating. It often results from blood clots or atherosclerosis.

Mesenteric ischemia can appear suddenly (acute) or persist over time (chronic). Sudden or severe intestinal ischemia is a medical emergency.

Symptoms include abdominal pain and bloating soon after eating. Any case of mesenteric ischemia needs medical help. If it happens or worsens suddenly, it is a medical emergency.

Here, learn more about mesenteric ischemia, the different types, how to recognize it, and what to expect if it happens.

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Small bowel or mesenteric ischemia occurs when the blood vessels leading toward or away from the small intestine become fully or partly blocked. This is often due to a blood clot, but it can happen for other reasons.

Types include:

  • Acute mesenteric ischemia: Appears or develops suddenly.
  • Chronic mesenteric ischemia: Develops over time.
  • Mesenteric venous thrombosis (MVT): Less common. In MVT, the veins leading blood away from the intestine become blocked, causing blood to back up around the small intestine, reducing blood flow and oxygen supply. This can lead to swelling and bleeding in the intestines.

All types can involve abdominal pain and discomfort. Symptoms may range from mild to severe, but any case of mesenteric ischemia needs medical attention.

Without treatment, tissue death in the small intestine can lead to sepsis and other complications.

Acute mesenteric ischemia and mesenteric venous thrombosis are medical emergencies and need urgent attention.

The symptoms of chronic and acute small bowel ischemia can be similar. The main difference is that acute symptoms are sudden and severe, while chronic symptoms worsen over time.

A person with acute mesenteric ischemia may experience:

A person with chronic mesenteric ischemia may have:

Not all cases of acute mesenteric ischemia involve a total blockage.

Both acute and chronic mesenteric ischemia can result from:

  • a blood clot in the arteries that bring blood to the intestine
  • low blood pressure
  • atherosclerosis
  • scar tissue that develops after surgery, which can obstruct the bowel or blood vessels
  • a hernia

An acute blockage involves a sudden drop in blood pressure and can result from:

  • a traumatic injury
  • a blood clot or scarring developing after surgery
  • a worsening of chronic mesenteric ischemia
  • low blood pressure due, for instance, to:
    • trauma or recent cardiac or abdominal surgery
    • heart failure
    • dehydration
    • drugs that reduce blood flow, such as Vasopressin
    • sepsis

In chronic ischemia, a person may live with reduced blood flow to the bowel for some time. Symptoms may worsen gradually, or the person may be under treatment to manage a known risk.

Around 40% to 50% of acute mesenteric ischemia cases are due to embolism, and 25% to 30% of cases are due to thrombosis.

Those most likely to experience acute mesenteric ischemia include:

  • females
  • older people
  • those who have recently had surgery
  • those with other health conditions, particularly cardiovascular disease

A person has a higher risk of chronic mesenteric ischemia if they:

To diagnose mesenteric ischemia, a doctor will likely:

  • ask about medical history, including any history of smoking
  • ask about symptoms
  • carry out a physical examination
  • order a CT scan
  • request an angiogram, in some cases, to look more closely at the blood vessels

Treatment options will depend on the cause and whether mesenteric ischemia is acute or chronic.

For acute mesenteric ischemia, options can include:

  • rehydration to provide fluid and balance electrolytes
  • surgery to identify the extent of damage and repair blood vessels
  • surgical removal of all or part of the bowel in 84% of cases
  • addressing any underlying conditions

For chronic mesenteric ischemia, a doctor may recommend:

  • quitting smoking, if appropriate
  • taking antiplatelet medication to lower the risk of a blood clot
  • surgery to implant a stent or establish a bypass
  • dietary changes, if necessary

Complications that can result from acute mesenteric ischemia include:

  • tissue death (necrosis)
  • intestinal rupture, where contents of the intestines leak into the abdominal cavity
  • peritonitis, or inflammation of the abdominal cavity
  • sepsis or septic shock
  • ventilator-related pneumonia during treatment
  • loss of all or part of the small bowel, making an ileostomy necessary
  • scarring of bowel tissue after treatment, leading to bowel narrowing
  • fatality, in some cases

People with chronic mesenteric ischemia have a higher risk of the following complications:

If a person has symptoms of sepsis, fever, or severe pain lasting 14 to 21 days or longer, a doctor will likely recommend surgery.

Mesenteric ischemia needs medical attention and can be a medical emergency.

A person needs medical help if they experience new pain, bloating, or blood in the stool.

They need emergency medical care if symptoms are sudden, severe, and occur with fever and other symptoms.

The outlook for mesenteric ischemia will depend on various factors, such as whether it is acute or chronic, the cause, and how soon a person receives medical care.

Acute mesenteric ischemia

Acute mesenteric ischemia has a high rate of fatality or ongoing health problems. Between 60% and 80% of people do not survive. Factors that increase the risk include:

  • older age
  • the need for bowel removal during a second surgery
  • metabolic acidosis, or high levels of acidity in the blood
  • kidney problems
  • having symptoms for a longer time

Seeking help as soon as symptoms arise can improve the outlook.

Chronic mesenteric ischemia

Chronic mesenteric ischemia can affect a person’s quality of life. They may find it hard to eat and become unwell with infections and other conditions that necessitate frequent medical treatment, including hospital admissions.

Mesenteric or small bowel ischemia is when the blood flow to the small intestine becomes reduced or blocked. It can be a medical emergency.

Possible causes include atherosclerosis, a hernia, a blood clot, scar tissue, and low blood pressure.

It is important for anyone experiencing severe or sudden intestinal symptoms to seek emergency medical help.