A diagnosis of HHT can often be made based on a physical examination, results of imaging tests and a family history. However, some symptoms may not yet be apparent in children or young adults at the time another family member is diagnosed with HHT.
Signs and symptoms of telangiectases and AVMs include shortness of breath, recurrent headaches, seizures, vision changes, anemia and blood in the stool. Symptoms depend on the location of the AVM.
A clinical diagnosis of HHT can be made if you have at least three of these four criteria:
- Recurrent nosebleeds that seem to start for no reason
- Visible telangiectases on your lips, the inside of your mouth, your fingers or your nose
- Internal telangiectases or AVMs on your lungs, brain, digestive tract or liver
- Family history of a parent, sibling or child with HHT
Genetic testing is available to identify the genetic cause of HHT and may sometimes help confirm a suspected diagnosis. If the test confirms the genetic cause of your HHT, this information can be used to test other family members to determine who needs to seek medical care for HHT health risks. The first step in undergoing genetic testing is to consult with a certified genetic counselor or medical geneticist. The genetic specialist will take a detailed family history, provide information about HHT, and discuss with you how genetic testing may be useful for you and your family.
It's likely your doctors will order imaging tests to check for telangiectases and AVMs as a part of your diagnosis. These imaging tests can include:
- Chest X-ray. A chest X-ray can help your doctor see the size, shape and structure of your lungs, and can give clues about the location and severity of any AVMs.
- Magnetic resonance imaging (MRI). Your doctor may order an MRI scan to check your brain for any abnormalities in your blood vessels. MRI is a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within your body. It's possible your doctor may give you a special type of dye (contrast medication) to make your blood vessels show up easily on the images produced by your MRI.
- Bubble echocardiogram. To screen for any abnormal blood flow caused by an AVM in your lung, your doctor may recommend this test. An echocardiogram uses sound waves to examine the blood flow through your vessels. In a bubble echocardiogram, you'll receive an injection of saline solution that has air bubbles in it, making it easier for your doctor to see how your blood is flowing and if there may be any vessel malformations.
- Computerized tomography (CT) scan. A CT scan combines a series of X-ray views taken from many different angles and computer processing to create cross-sectional images of the bones and soft tissues inside your body. If a bubble echocardiogram reveals you may have a lung AVM, your doctor may order a CT scan of your lungs to confirm the diagnosis and see if your AVM needs any treatment, such as surgery. Your doctor may also order a CT scan of the abdomen to look for telangiectases in the liver.