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.