Pulmonary arteriovenous malformations (PAVMs) represent a direct communication between one or more pulmonary arteries and one or more pulmonary veins. Common anatomic forms include single sacs ranging from 1 to > 10 cm in diameter, macroscopic tangles, and microscopic telangiectases. The main complications of PAVMs are believed to relate to right-to-left shunting of blood through the PAVM and include stroke and brain abscess, which together occur in up to one half of patients if untreated.1 Other potentially serious complications include refractory hypoxemia, hemoptysis, and hemothorax. Fortunately, nearly all of these complications can be prevented by embolization of the feeding arteries (transcatheter embolotherapy [TCET]). PAVMs are associated with underlying hereditary hemorrhagic telangiectasia (HHT) in up to 90% of cases. Conversely, at least 30% of patients with HHT will also have PAVMs. In order to prevent the complications noted above, various screening strategies for PAVMs have been proposed in patients with known HHT or their undiagnosed relatives.1–4 The main screening tests are reviewed in the following paragraphs.