Hypoxaemia during pregnancy: pulmonary arteriovenous dilatation as a likely cause

Saline contrast-enhanced transthoracic echocardiography showing a positive contrast test for intrapulmonary vascular dilatation diagnosis. Arrows indicate microbubbles inside the a) right atrium and b) just after transit through the left atrium. Microbubbles entered the left atrium 3.5 s (four to five cardiac cycles) after they passed through the right atrium. bpm: beats per minute.