Abstract:

Objective To analyze retrospectively the results of amniotic fluid cell culture and chromosome karyotypes among 2 018 fetuses in the 2nd trimester pregnancy,and to investigate the relationships of abnormal chromosome karyotypes and proportions with the syndromes of prenatal diagnosis and the pregnancy outcomes for fetuses with abnormal mosaic karyotypes. Methods Amniotic fluid samples were extracted from pregnant women according to prenatal diagnosis syndromes,whose gestational ages were 16 to 24 weeks. The samples were determined for amniotic fluid cell culture and chromosome karyotypes. Results A total of 61 cases of abnormal chromosome karyotypes were determined,and the abnormal rate was 3.0%（61/2 018）. The abnormal rates in groups with high risk results of serological screening,high pregnant ages（≥35 years old）,abnormal ultrasound determination results and adverse pregnancy or family history were 2.8%,2.3%,9.2% and 10.6%,respectively. The abnormal rates between the groups with high risk results of serological screening and high pregnant ages showed no statistical significance（P>0.05）. A total of 43 cases of numerical abnormality of chromosome karyotypes were determined,including 23 cases of trisomy 21,9 cases of trisomy 18 and 1 case of trisomy 13 and 10 cases of sex chromosome. There were 12 cases of structural abnormality of chromosome karyotypes,including 7 cases of balanced translocation,2 cases of Robertsonian translocation,1 case of insertion,1 case of deletion and 1 case of inversion. Furthermore,6 cases of mosaic karyotypes were determined,and 2 pregnant women of the 6 cases with low proportion gave birth to their babies,but they showed no abnormal phenotypes after follow-up. Conclusions There are high abnormal rates under different syndromes of prenatal diagnosis. Fetuses with low proportion of mosaic karyotypes may have normal phenotypes. Amniotic fluid chromosome karyotype analysis can provide a reliable reference for the diagnosis of fetal chromosome abnormalities.

Key words: Chromosome, Prenatal diagnosis, Amniocentesis