Asymptomatic hypoxia in a young pregnant lady - Unusual presentation of atrial septal defect

Atrial septal defect (ASD) accounts for approximately a third of all congenital heart disease in adults. It is rarely diagnosed and less likely to cause any symptoms during infancy, but approximately more than half become symptomatic around their fifth decade. In clinical setting it commonly presents as exertional dyspnoea, atrial arrhythmias, right heart failure and is rarely related to the thromboembolic complications due to paradoxical embolism. ASD is usually well tolerated in pregnancy with low risk of miscarriages, stillbirth, preterm delivery and perinatal mortality. We report an interesting case of undiagnosed large ostium secundum atrial septal defect in a young pregnant lady presented as 'asymptomatic hypoxia'. All pregnant women with hypoxia either pre or post-partum should be investigated to rule out any undiagnosed intra cardiac shunts to minimise maternal and foetal complications.