A new strategy for prenatal diagnosis of homozygous α 0- thalassemia

Abstract

Objectives: We have shown previously that ultrasound examination performed by one experienced operator can be useful to exclude homozygous α 0-thalassemia in a tertiary referral center. This study aimed to determine whether the technique was still applicable when performed by several operators and in different centers. Methods: At the Maternal and Neonatal Hospital of Guangzhou (MNH) and Tsan Yuk Hospital of Hong Kong (TYH), women at risk of homozygous α 0-thalassemia were given the option of a non-invasive approach (using serial ultrasound examinations at 12-15, 16-20 and 25-30 weeks' gestation) to exclude an affected pregnancy. The fetal cardiothoracic ratio (CTR) was measured at each of these examinations and the placental thickness was measured at 12-15 weeks' gestation. The operators of MNH received training on the ultrasound examination techniques at TYH and the quality of the subsequent ultrasound examinations was checked regularly. The final diagnosis of homozygous α 0-thalassemia was confirmed using an invasive test. Results: Of 832 at-risk pregnancies studied in the two hospitals, 168 (20.2%) were affected. The overall sensitivity and specificity of the non-invasive approach was 100% and 95.6%, respectively. At MNH, the need for an invasive test was reduced by 80.8%, and all the affected pregnancies were diagnosed before 24 weeks' gestation. The results achieved at MNH were comparable with those at TYH. The at-risk pregnancies including the affected ones presented at a more advanced gestational age at MNH. At each hospital, one affected pregnancy was missed at the 12-week scan but this was subsequently detected at the 15-18-week scan. Conclusions: This non-invasive approach to exclude homozygous α 0-thalassemia can be applicable when it is performed by several operators and in different centers. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.