Pulmonary arteriovenous malformations (pAVMs) are abnormal connections between branches of the pulmonary artery and vein resulting in right-to-left shunting of blood. They are the most common pulmonary vascular malformations, with an estimated incidence of 1 in 2600, and typically congenital.1 There is a 30% lifetime risk of shunt related complications, such as stroke or cerebral abscess, secondary to paradoxical emboli.1 Rarer vascular malformations include pulmonary varix (PV), a congenital or acquired dilatation of a pulmonary vein and meandering pulmonary vein (MPV). In MPV, a single pulmonary vein, usually in the right hemithorax, takes an unusual tortuous route (often crossing fissures) before draining into the left atrium (LA).2 There are no known reports of these pathologies co-existing. Correct diagnosis is key as pAVMs require embolisation to reduce the risk of complications, while other vascular abnormalities may not need intervention.

A woman in her 30s presented at 8 weeks pregnant reporting worsening breathlessness on exertion. Saturations on air were 97%–100%. She had a pre-existing diagnosis of asthma (on inhaled therapy), allergic rhinitis and probable breathing pattern disorder. A CT pulmonary angiogram …