Comparison of early and mid-trimester amniocentesis in 1459 amniotic fluid cultures

Early amniocentesis is a new context in prenatal diagnosis. However, the consequences of this procedure are not known clearly. We compared cytogenetic results of 655 amniotic fluid samples obtained at 12-14 gestational weeks (early amniocentesis, EA) and 804 samples at 15-18 gestational weeks (mid-trimester amniocentesis, MA). The rate of chromosomal abnormalities for early amniocentesis was 3.2% (21 cases) and for mid-trimester amniocentesis was 5.3% (43 cases) (p=0.047). True mosaicism was seen in 2 cases MT group (p=1.000). We did not have maternal cell contamination in either group. The ratio of repeat amniocentesis was 0.6 percent in the EA group compared with 0.2 percent in MA group (p=0.417). Procedure-related early abortion (within the first 30 days after amniocentesis) was seen in 4 cases of EA (2.2%) and 3 cases of MA (1.5%) (p=0.719). Hemorrhage occured in the same ratio. Intra-uterine fetal death (IUFD) was seen in 7 cases of MA, but not in any cases of EA (p=0.015). Our findings showed comparable outcome in two method of amniocentesis, except for lower chromosomal abortion rate and IUFD.