Screening establishes the baseline for informed HHT care.
Lung AVMs and brain VMs are the manifestations for which presymptomatic screening is recommended, because both can cause serious events without warning. Filter the protocol below by who is in front of you and which system you are investigating.
Screening protocol
What to screen for, and when
13 topics
Pulmonary AVMs — adults
Screen all patients with possible or confirmed HHT. Timing depends on age and, to a lesser degree, on symptoms; preferably patients have been screened by their early teens. Transthoracic contrast echocardiography is the screening test of choice. When the bubble study is more than minimally abnormal, chest CT determines location and whether the lesion is large enough to treat.
Pulmonary AVMs above a certain size should be embolized to prevent brain abscess and stroke. For smaller lesions, antibiotic prophylaxis before dental work and other non-sterile invasive procedures is recommended.
Until pulmonary AVMs are excluded by testing, a person over the age of ten with known or suspected HHT should take antibiotics before all dental cleanings, dental work, and any procedure carrying a risk of introducing bacteria into the bloodstream. If a pregnant patient has not had a recent evaluation, arrange it as soon as the pregnancy is recognized.
Brain VMs — adults
The rationale for screening is that it detects a treatable brain VM before a life-threatening or debilitating complication develops. MRI with and without gadolinium is the recommended study. Because brain VMs can cause hemorrhage in infants, a brain MRI early in life is recommended.
No evidence currently supports routine follow-up screening after an initial negative study in childhood, but consideration should be given to one adulthood MRI following a negative childhood MRI.
Anemia and iron deficiency — adults, annually
Screen all adults with HHT annually regardless of symptoms, along with any child who has recurrent bleeding or symptoms of anemia, and more frequently when clinically indicated. Screening consists of a complete blood count, an iron panel (serum iron, total iron binding capacity, transferrin saturation), and ferritin.
A complete blood count alone can miss iron deficiency without anemia, which is why the iron panel and ferritin belong in the same draw.
Gastrointestinal bleeding — adults
Endoscopy is the first-line diagnostic test for suspected HHT-related bleeding. Capsule endoscopy may be appropriate when upper endoscopy does not reveal significant HHT-related telangiectasia. Patients who meet colorectal cancer screening criteria, and patients with a SMAD4 variant whether genetically proven or suspected, should also have regular colonoscopies.
Roughly 3% of patients with HHT carry a SMAD4 variant and overlap with juvenile polyposis syndrome. These patients are at high risk of colorectal cancer and should be screened frequently starting at age 15. They are also at risk for heart and joint problems and require appropriate screening. Patients with HHT and no juvenile polyposis carry colorectal cancer risk comparable to the general population.
Liver VMs — adults
Diagnostic testing is recommended for patients with symptoms or signs suggestive of complicated liver VMs: heart failure, pulmonary hypertension, abnormal cardiac biomarkers, abnormal liver function tests, abdominal pain, portal hypertension, or encephalopathy. Presymptomatic screening is not currently recommended for everyone and can be discussed case by case.
Doppler ultrasound is the preferred first-line investigation, given its safety, tolerability, low cost, and accuracy. CT has been recommended where Doppler expertise is lacking. MRI provides excellent accuracy with both multiphase anatomic assessment and hemodynamic characterization. Once a liver VM is detected, echocardiographic evaluation assesses its effect on cardiac function, and right-heart catheterization is performed where there are signs or symptoms of heart failure or possible pulmonary hypertension. Referral for liver transplant is indicated for symptomatic complications.
Liver biopsy should be avoided in any patient with proven or suspected HHT. Hepatic artery embolization should be avoided in patients with liver VMs, as it is associated with significant morbidity and mortality.
Epistaxis and anticoagulation — adults
Epistaxis management is stepped: moisturizing topical therapy first, then antifibrinolytic therapy, then ablative options such as laser, radiofrequency, electrosurgery, or sclerotherapy. Systemic antiangiogenic therapy and surgical options are reserved for severe or refractory bleeding. Iron replacement runs alongside: oral iron first, intravenous iron when oral therapy does not keep pace, transfusion reserved for defined situations.
Anticoagulant and antiplatelet therapy may be used in HHT when indicated, with stated agent preferences. It calls for a considered risk assessment rather than a reflexive refusal, ideally with input from an HHT center.
Annual review and specialist follow-up — adults
A yearly evaluation by the primary care physician is recommended, with an annual check of ferritin, hematocrit, and hemoglobin. Most HHT Centers of Excellence see patients every three to five years, or as symptoms warrant.
Without periodic review by someone who knows HHT, complications are frequently missed, misdiagnosed, or mismanaged, and the consequences can be catastrophic.
Pulmonary AVMs — children
Screen asymptomatic children who have HHT or are at risk for it at the time of presentation or diagnosis, and repeat screening at approximately five-year intervals. The initial screen is pulse oximetry plus chest X-ray. Transthoracic contrast echocardiography has higher sensitivity and does not involve radiation, and it is the recommended screen for symptomatic children: those with low oxygen levels, shortness of breath, difficulty keeping up in sports, or prior neurologic complications. When a screening test is positive, CT is the next step to determine where the lesions are and whether they are large enough to treat.
Most HHT Centers recommend repeat lung AVM screening every three to five years when pulse oximetry reads 97% or higher. Below 97%, or if the child is short of breath, additional tests or treatment may be required. Large pulmonary AVMs, and those associated with reduced oxygen saturation, should be treated in children to avoid serious complications.
Brain VMs — children
Screening for brain VMs in asymptomatic children who have HHT or are at risk for it is recommended at the time of presentation or diagnosis. Brain VMs with high-risk features should be treated.
The Clinical Guidelines record no consensus on recurring testing in children. Most HHT Centers screen for brain VMs in the first year of life, or at the time of diagnosis, and perform at least one follow-up MRI at puberty, since brain VM development appears to correlate with periods of growth.
Genetic testing — children
Diagnostic genetic testing should be offered for asymptomatic children of a parent with HHT. Some children do experience complications from pulmonary AVMs, which is why HHT clinicians advocate screening every child of a parent who has HHT rather than waiting for symptoms.
Pulmonary AVMs — pregnancy
Increased cardiac output, increased blood volume, and high progesterone levels can together cause pulmonary AVMs to enlarge or rupture. Complications can occur at any point, though 85 to 90% occur in the second or third trimesters. For previously treated pulmonary AVMs the risk is not precisely known but may be around 5%.
In asymptomatic patients, initial screening uses either agitated saline transthoracic contrast echocardiography or low-dose non-contrast chest CT, depending on local expertise; where CT is used, perform it early in the second trimester. In patients with symptoms suggestive of pulmonary AVM, use low-dose non-contrast chest CT at any gestational age as clinically indicated. Treat pulmonary AVMs starting in the second trimester unless otherwise clinically indicated.
Screen and treat as early as possible, at roughly 12 to 20 weeks. Patients with prior negative screening need no additional screening during pregnancy in the absence of symptoms. Patients who have not been recently screened or treated should be screened and treated during the pregnancy. Embolization carries a procedural risk of bleeding, transient ischemic attack or stroke, and sedation reaction, in under 1% of cases and usually minor.
Brain VMs — pregnancy
Asymptomatic patients do not require routine brain VM screening during pregnancy. Around 10% of women with HHT present with an asymptomatic brain VM, and where there are no symptoms, treatment is usually deferred until after pregnancy given the low risk of bleeding. Pregnant patients with symptoms suggestive of brain VM, including anyone with a previous brain bleed, should be screened using unenhanced MRI, without gadolinium, in the second trimester.
0.5% of unscreened women present with a brain bleed during pregnancy or after giving birth. Where there has been prior bleeding from a brain VM, the risk of re-bleeding rises to as much as 30%, mainly in the second and third trimesters and after birth.
Uterine AVMs — pregnancy
Uterine AVMs are more likely to be related to previous uterine procedures than to HHT itself. Treatment is uterine artery embolization.
Every pregnant patient with HHT presents differently and needs personalized advice, ideally from an HHT expert. With the right screening, most patients with HHT have a normal pregnancy and delivery at no greater risk than someone without HHT.
Clinical checklists
Put the checklist next to the topic
Downloadable care checklists exist for the topics above, and they work best when they are handed over in the same visit rather than left for the patient to find later. The comprehensive patient guide covers the same ground in plain language.
For tracking epistaxis over time, the Nosebleed Severity Score gives a repeatable measure of current severity and treatment response, which turns a subjective complaint into something comparable between visits.
Iron and anemia at a glance
Test
All adults with HHT, regardless of symptoms; children with recurrent bleeding or anemia symptoms
Replace
Oral iron first; intravenous iron when oral therapy does not keep pace
Transfuse
Reserved for hemodynamic instability, comorbidity, pre-procedure need, or failure of infusion therapy
Reassess
Consider folate deficiency, B12 deficiency, or hemolysis when iron replacement is not working
Screening recommendations on this page follow the Second International Guidelines for the Diagnosis and Management of Hereditary Hemorrhagic Telangiectasia (Faughnan et al., Annals of Internal Medicine, 2020, 173(12), 989–1001). Pediatric screening practice also draws on Sekarski and Spangenberg, Pediatric Nursing, 2011, 37(4), 163–168. The Guidelines remain the authoritative source for specific tests, thresholds, evidence grades, and intervals.