Second-trimester hydrops fetalis in pregnancies affected by homozygous alpha-thalassaemia-1

Homozygous alpha-thalassaemia-1 is the commonest cause of hydrops fetalis in South-East Asia. Ultrasonographic features of hydrops fetalis were said to be evident only after 20 weeks of gestation. We studied 111 pregnancies at risk of homozygous alpha-thalassaemia-1 at 12-14 gestational weeks and 101 pregnancies at 17-18 weeks by abdominal ultrasound examination. Ultrasonographic features of hydrops fetalis were seen in 3 out of 44 pregnancies affected by homozygous alpha-thalassaemia-1 at 12-14 weeks [7 per cent; 95 per cent confidence interval (CI) 1-19 per cent] and in 7 out of 21 affected pregnancies at 17-18 weeks (33 per cent; 95 per cent CI 15-57 per cent). In conclusion, homozygous alpha-thalassaemia-1 can cause hydrops fetalis in the early second trimester. It should constitute one of the differential diagnoses in the work-up of second-trimester hydrops fetalis.