Definition of Angiodysplasia
Angiodysplasia – Abnormal Vascular Formations
Angiodysplasia is abnormal vascular formations found in the bowel. They are usually found in the ascending colon and the cecum. Bleeds can be minimal or quite severe, resulting in anemia. Angiodysplasia differs from arteriovenous malformations (AVM). AVM’s are usually large and solitary while angiodysplasia lesions are often present as multiple small lesions.
Epidemiology of Angiodysplasia
Spread of Angiodysplasia
Angiodysplasia is one of the most common vascular malformations of the GI tract and the second most common source of lower GI bleeding after diverticulosis. They are most often found in the elderly, specifically those over 60. Asymptomatic angiodysplasia is as common as 1% in the patients over 50 years. There is no difference between the sexes or the different races.
Etiology of Angiodysplasia
Causes of Angiodysplasia
The exact cause of angiodysplasia is unknown. The foremost theory involves progressive degeneration of small submucosal vasculature in the GI tract that accumulates with age. Risk factors include heart disease (aortic stenosis), renal disease and coagulopathy.
Pathology and Pathophysiology of Angiodysplasia
Angiodysplasia lesions are most frequently found in the cecum and right colon, but they can also be found in the stomach and small intestine. The exact cause of GI angiodysplasia is unknown. Chronic venous obstruction may play a role.
During the normal functioning of the large intestine, the walls become distended, especially in the right colon with the largest lumen. During times of heavy load, the venous outflow from the submucosa may become transiently obstructed. After this process repeats during years of use, the precapillary arterioles lose their ability to regulate blood pressure and the angiodysplasia malformation forms. This theory explains why they are most commonly found in the elderly population.
Symptoms of Angiodysplasia
Signs of Angiodysplasia
Many patients are asymptomatic with the diagnosis made during a screening colonoscopy. They will present with a transient GI bleed. Melena (dark blood) is an indication of an upper GI bleed while hematochezia may indicate a lower GI bleed. Patients with an aggressive bleeding may also suffer from iron deficiency anemia with symptoms of lethargy, weakness, fatigue and malaise.
Diagnosis of Angiodysplasia
Asymptomatic angiodysplasia of the intestines is ignored. If found on routine colonoscopy, they are evaluated on future colonoscopies. Only actively bleeding lesions are treated. As with all GI bleeds, the first step is to determine if the bleed is an upper bleed (peripheral to the ligament of Treitz) or inferior bleed (distal to the ligament of Treitz).
- Upper bleeds often present with hematemesis, but may also show melena, black tarry stool.
- A lower GI bleed will present with melena and diarrhea (blood acts as an isotonic laxative) or hematochezia.
Once a rough estimation of the location of the bleed is determined and the patient is stabilized, a colonoscopy is performed to visualize the colon for bleeds or abnormalities. Severe bleeds may prevent colonoscopy. If the bleed remains elusive, a mesenteric angiography, or a radionuclide scan, will be used to determine its location. Histology is not useful when diagnosing angiodysplasia.
Differential Diagnoses of Angiodysplasia
Clinical Pictures Similar to Angiodysplasia
Therapy of Angiodysplasia
Treatment of Angiodysplasia
Once the angiodysplasia lesion is found, it must be treated to stop active bleeding and prevent future bleeding. The preferred treatment is endoscopic obliteration with the heat probe, laser photocoagulation or argon plasma coagulation. Additionally, transarterial embolization is a well-tolerated alternative. These techniques risk re-bleeding. Resection is the definitive treatment. Right hemicolectomy is the next level of treatment after endoscopic obliteration fails, but even patients treated with this therapy may develop an additional lesion and begin bleeding again.
Progression and Prognosis of Angiodysplasia
Angiodysplasia lesions are often asymptomatic. Of those that bleed, 90% spontaneously cease bleeding without intervention. Large bleedings may lead to hemodynamic instability and anemia.
The correct answers can be found below the references.
1. A 67-year-old woman with a past medical history of aortic stenosis presents with decreased energy for the past three months. The physical exam is notable for conjunctival pallor. Hemoglobin is measured at 9.1 g/dL. On the colonoscopy, several small red lesions are noted in the otherwise normal colonic mucosa. What is the likely diagnosis?
- Cancerous growth
- Bowel wall ischemia
- Mucosal out pocketing
2. A 74-year-old patient presents to the ED with painless heavy rectal bleeding. His laboratory results are normal. After you stabilize him, what is your next step?
- Upper endoscopy
- Radionuclide scan