Lam Y H, Tang M H
Department of Obstetrics and Gynaecology, University of Hong Kong, Tsan Yuk Hospital, Hong Kong.
Prenat Diagn. 1997 Jun;17(6):501-4. doi: 10.1002/(sici)1097-0223(199706)17:6<501::aid-pd89>3.0.co;2-l.
Couples with alpha-thalassaemia-1 face a 25 per cent risk of having fetuses with haemoglobin (Hb) Bart's disease. Prenatal diagnosis is conventionally performed by DNA studies of chorionic villi or amniocytes obtained from chorionic villus biopsy or amniocentesis. DNA studies are expensive and time-consuming. We identified 11 affected pregnancies on abdominal ultrasound examination at 12-14 weeks when the placental thickness exceeded the mean plus 2 SD measurement for the gestational week and the cardiothoraic ratio was more than 0.5. Cordocentesis was then performed with a free hand technique. The procedures were successful in ten cases using a 26-gauge spinal needle with a 20-gauge introducer. Hb Bart's disease was confirmed in all cases by Hb electrophoresis. The procedure was unsuccessful in one case when a 22-gauge spinal needle was used. Hb study of fetal blood collected at abortion also confirmed Hb Bart's disease. In conclusion, ultrasound findings of concomitant placentomegaly and cardiomegaly at 12-14 weeks is highly specific of disease in pregnancies at risk of Hb Bart's disease. Cordocentesis and Hb study in pregnancies with these sonographic manifestations may be an alternative prenatal diagnostic approach. This diagnostic approach is of particular value in areas where resources for molecular studies are limited.
患有α地中海贫血1型的夫妇生育血红蛋白（Hb）Bart's病胎儿的风险为25%。传统的产前诊断是通过对绒毛取样或羊膜穿刺术获取的绒毛膜绒毛或羊水细胞进行DNA研究。DNA研究既昂贵又耗时。我们在妊娠12至14周进行腹部超声检查时，识别出11例受影响的妊娠，此时胎盘厚度超过孕周平均测量值加2个标准差，心胸比大于0.5。然后采用徒手技术进行脐带穿刺。使用带20号导引器的26号脊椎穿刺针，该操作在10例中成功。通过血红蛋白电泳在所有病例中均确诊为Hb Bart's病。使用22号脊椎穿刺针时，该操作在1例中未成功。对流产时采集的胎儿血液进行血红蛋白研究也确诊为Hb Bart's病。总之，妊娠12至14周时出现胎盘肿大和心脏肿大的超声表现对有患Hb Bart's病风险的妊娠具有高度特异性。对有这些超声表现的妊娠进行脐带穿刺和血红蛋白研究可能是一种替代的产前诊断方法。这种诊断方法在分子研究资源有限的地区具有特别价值。
