An increase of the cardiothoracic ratio leads to a diagnosis of Bart's hydrops.

BACKGROUND: Thalassemia is a common single gene disorder in Southeast Asia. a-thalassemia is a group of syndrome characterized by deficient production of the alpha-globin chain. Individuals with heterozygous alpha-thalassemia-1 are at risk of having a fetus that has Hemoglobin Bart's hydrops fetalis (Hb Bart's). Usually, when the hemoglobin electrophoresis in heterozygous alpha-thalassemia-1 is normal, the Mean Corpuscular Volume (MCV) is lowered. We report a case of increased cardiothoracic ratio that led to a diagnosis of Hb Bart's in a couple who had normal hemoglobin electrophoresis and low MCV. CASE REPORT: A 23-year-old woman, gravida 2, Para 0-0-1-0, initially presented for antenatal care at 13 weeks pregnancy. Her MCV was 67 fentolitre, DiChlorophenol-IndolPhenol (DCIP) test was negative and hemoglobin electrophoresis was normal. Her husbands MCV was 67 fentolitre, and hemoglobin electrophoresis was normal. Cardiomegaly (an increased of the cardiothoracic ratio) was detected by ultrasonogram at 25 weeks of gestation. She and her husband were comprehensively counseled after an Hb Bart's was suspected. A cordocentesis was performed and the fetal blood was tested for hemoglobin electrophoresis. The result was later known and confirmed as Hb Bart's. The couple decided to terminate the pregnancy. The induced abortion was successful and the patient was discharged on the second day after the abortion. She was well at the 4-week follow-up. CONCLUSION: A prenatal ultrasonographic screening should be conducted in couples who are suspected of being alpha-thalassemia-1 carriers when DNA study of alpha-globin gene cannot be performed. The increase of cardiothoracic ratio will help detect an early stage of Hb Bart's.

Prenatal diagnosis of hemoglobin Bart's hydrops fetalis by HPLC analysis of hemoglobin in fetal blood samples.

Since HbF and HbA are not found in fetuses with Hb Bart's hydrops fetalis the feasibility of prenatal diagnosis of homozygous alpha-thalassemia 1 by fetal hemoglobin typing was examined. Blood samples were obtained from fetuses at 18 to 22 weeks of gestation by cordocentesis in 32 pregnant women at risk of having a child with homozygous alpha-thalassemia 1 (alpha-thal-1). The samples were analyzed by a PCR-based method for the diagnosis of alpha-thal-1 (SEA type) and the proportion of hemoglobin fractions were determined by automated HPLC. DNA analysis showed that 8 of the 32 fetuses were homozygotes for alpha-thal-1, 17 were heterozygous for alpha-thal-1 (alpha-thal-1 trait), and a normal complement of four a-globin genes was found in 7 cases. The Hb typing in fetuses with homozygous alpha-thal-1 showed a peak of unbound Hb (Hb Bart's and Hb Portland) and no HbF, HbA and HbA The alpha-thal-1 trait chromatograms showed unbound Hb, pre HbF, HbF and HbA peaks. The chromatogram of normal fetuses showed HbF and HbA peaks without HbA2. In these cases the HbA proportion is between 3% and 10% with no apparent differences between the 18h and 22nd week of gestation. As the analysis of fetal Hb types by HPLC is facile and speedy and the results correspond with those obtained by DNA analysis, fetal Hb typing by automated HPLC is a convenient prenatal diagnostic method for homozygous alpha-thal-1. The method is recommended for prenatal diagnosis in populations with a high frequency of alpha-thal-1.