[Prenatal diagnosis in the 1st trimester of pregnancy of the male fetus at risk for hemophilia B].

It is for the first time that chorionic villi biopsy was performed for diagnostic purposes; the indication for prenatal testing was haemophilia B-X-linked disease. The chorionic tissue was obtained by transcervical aspiration in the 9th week of gestation under ultrasound guidance. The techniques used for cytogenetic investigation were the Y body technique and direct fetal karyotyping. The presence of Y body was determined by slide examination. The analysis of the fetal karyotype confirmed the diagnosis of a male fetus. As this fetus had a great risk (50%) of being born with haemophilia B, the parents decided to terminate the pregnancy. It was done 9 days following the test. During this period no complications were observed. The chorionic villi biopsy has proved easy, quick, and successful in the diagnosis of X-linked disorders.