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Colonic Arteriovenous Malformation

Last updated Nov. 8, 2019

Approved by: Krish Tangella MD, MBA, FCAP

Colonic Arteriovenous Malformation is a benign condition that may have a congenital origin. An arteriovenous malformation (AVM) is an abnormal connection between the veins and arteries resulting in collection of vascular malformation. It can occur anywhere in the body.


What are the other Names for this Condition? (Also known as/Synonyms)

  • Arteriovenous Malformation of Colon
  • Arteriovenous Malformation of Large Intestine
  • Colonic AVM

What is Colonic Arteriovenous Malformation? (Definition/Background Information)

  • Colonic Arteriovenous Malformation is a benign condition that may have a congenital origin. An arteriovenous malformation (AVM) is an abnormal connection between the veins and arteries resulting in collection of vascular malformation. It can occur anywhere in the body
  • Colonic AVM can result in gastrointestinal tract bleeding and anemia. The cause of this malformation is generally unknown, but it is linked to Osler-Weber-Rendu syndrome, the use of anticoagulant medications, bleeding disorders, and Heyde syndrome
  • The diagnosis of Colonic Arteriovenous Malformation may involve various blood tests including stool test for occult blood, and imaging tools such as colonoscopy and angiographic studies, which may help detect active bleeding within the GI tract
  • Periodic observation may be maintained for asymptomatic cases. Surgical management may be proposed, depending on the signs and symptoms caused by this arteriovenous malformation. Anemia may have to be treated using iron-rich foods and blood transfusions, if required
  • The prognosis of an individual with Colonic Arteriovenous Malformation is typically excellent with suitable treatment. However, the prognosis also depends upon the severity of the condition

Who gets Colonic Arteriovenous Malformation? (Age and Sex Distribution)

  • Colonic Arteriovenous Malformation are usually present at birth or following birth (congenital manifestation). However, the symptoms due to the malformation may occur at any age in one’s life
  • Both males and females are affected
  • There is no known predilection towards any ethnic or racial group; the condition is seen worldwide

What are the Risk Factors for Colonic Arteriovenous Malformation? (Predisposing Factors)

The risk factors for Colonic Arteriovenous Malformation include the following:

  • Osler-Weber-Rendu syndrome - a rare hereditary disorder
  • Taking blood thinners or anticoagulants (anti-platelet medications)
  • Bleeding disorders such as von Willebrand factor (vWF) deficiency
  • Prolonged constipation
  • Chronic renal failure patients on dialysis
  • Heyde syndrome; in which there is GI bleeding due to angiodysplasia in individuals with aortic stenosis and acquired von Willebrand factor disease (2A deficiency)

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Colonic Arteriovenous Malformation? (Etiology)

  • The exact cause of Colonic Arteriovenous Malformation is unknown, but studies indicate that it is a congenital malformation
  • The condition arises owing to malformations in arteries and veins of the large intestine (colon). It is associated with AVMs in other parts of the body

What are the Signs and Symptoms of Colonic Arteriovenous Malformation?

The signs and symptoms of Colonic Arteriovenous Malformation may appear anytime during one’s life and may include:

  • The presence of a single tumor; multiple AVMs are rarely observed
  • The tumors are over 5 mm in size (they are typically large enough to be spotted through imaging/diagnostic studies)
  • Gastrointestinal tract bleeding, which can be mild or profuse
  • Profuse bleeding can cause black tarry stools (melena)
  • Chronic bleeding can result in anemia with symptoms including pale skin, lethargy and/or fatigue, poor appetite, lightheadedness, irritability and headaches

In some cases, the condition may be asymptomatic (presenting no significant signs and symptoms).

How is Colonic Arteriovenous Malformation Diagnosed?

Colonic Arteriovenous Malformation is diagnosed with the help of the following tests and exams:

  • Complete physical exam with comprehensive evaluation of medical history
  • Complete blood count (CBC): This measures the red blood cell count and hemoglobin levels in blood. Low levels of hemoglobin and/or RBC count can indicate iron deficiency
  • Fecal occult blood test (FOBT):
    • This test is used to check if there is bleeding in the gastrointestinal tract
    • The test is usually positive, when there is active bleeding; the test can be negative, when the individual is not bleeding (silent period)
  • Tests such as partial thromboplastin time (PTT) and prothrombin time (PT), to check for blood coagulation
  • Colonoscopy:
    • A colonoscopy is a test that allows the physician to look at the inner lining of the colon and rectum
    • A typical colonoscopy involves using a thin, flexible tube (called a colonoscope), with an attached video camera, to view the colon and rectum
  • Capsule endoscopy (enteroscopy) and colonoscopy: Also, known as pill endoscopy and colonoscopy, it is a diagnostic tool in which a small capsule/pill with an attached camera is swallowed. As the pill goes through the small/large intestines, the camera visualizes the lining of the bowel to detect site of the bleeding
  • Selective GI angiography
  • Multiphase CT angiography: It is another technique, which can help detect an active bleeding
  • Radioactive scintigraphy can also help detect active bleeding in the GI tract

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Colonic Arteriovenous Malformation?

The complications from Colonic Arteriovenous Malformation could include:

  • Chronic and recurrent bleeding
  • Emotional trauma due to chronic bleeding episodes
  • Severe and acute bleeding can even be life-threatening
  • Chronic blood loss can lead to iron deficiency anemia
  • Anemia can also cause impairment in intellectual functioning, behavioral problems, etc.
  • Damage to vital nerves, blood vessels, and surrounding structures during surgery

How is Colonic Arteriovenous Malformation Treated?

The treatment measures for Colonic Arteriovenous Malformation may include the following:

  • Endoscopic cautery using techniques such as argon plasma coagulation
  • Arterial embolization
  • Medications to help with coagulation, such as antifibrinolytics, and treatment using estrogen hormone
  • If the individual has severe anemia (or iron-deficiency anemia), then the following treatment may be provided:
    • Blood transfusions for severe blood loss
    • Use of iron supplements and iron-rich diet (that include meats, spinach, eggplant, dried fruits, poultry, eggs, and iron-fortified cereals)
  • If conservative measures fail, or if the bleeding is severe, then surgery to resect a portion of the intestine (partial bowel resection) may be undertaken
  • Post-operative care is important: Minimum activity level is to be ensured until the surgical wound heals
  • Follow-up care with regular screening and check-ups are important

Individuals with asymptomatic Colonic AVMs may not need treatment. Such individuals may be monitored by the healthcare provider on a regular basis.

Note: Estrogen therapy can have unwanted side effects, and so, a risks v/s benefits analysis must be conducted before commencing therapy.

How can Colonic Arteriovenous Malformation be Prevented?

  • Current medical research has not established a method of preventing Colonic Arteriovenous Malformation formation
  • However, if the condition is caused or aggravated by hard stools, then taking steps to avoid chronic constipation may be beneficial
  • Early diagnosis and treatment will help prevent complications due to Colonic AVM, such as severe bleeding incidences

What is the Prognosis of Colonic Arteriovenous Malformation? (Outcomes/Resolutions)

  • The prognosis of Colonic Arteriovenous Malformation is generally excellent with adequate and appropriate treatment
  • However, the prognosis also depends upon the severity of bleeding episodes, the age and overall health of the individual
  • Individuals with increased blood pressure have higher chances of bleeding for AVM

Additional and Relevant Useful Information for Colonic Arteriovenous Malformation:

Gastrointestinal angiodysplasia is not similar to a Colonic Arteriovenous Malformation, because a GI angiodysplasia is usually small and many in numbers. It is also not possible to generally identify angiodysplasia via an endoscopy, unlike a Colonic AVM.

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: May 4, 2017
Last updated: Nov. 8, 2019