PROCEDURE-RELATED FETAL LOSSES IN TRANSPLACENTAL VERSUS NONTRANSPLACENTAL GENETIC AMNIOCENTESIS

OBJECTIVE: We hypothesize that loss rates after amniocentesis do not d iffer in transplacental and nontransplacental taps performed by experi enced operators.STUDY DESIGN: Subjects were 1000 women undergoing seco nd-trimester amniocentesis: 745 were referred for maternal age; 132 fo r positive maternal serum alpha-fetoprotein screens, 41 indicating a r isk for fetal neural tube defect, 91 indicating a risk for fetal chrom osome abnormality; and 123 were referred for other reasons. All proced ures were videotaped. The placenta was anterior in 518 cases; in 306 o f these the needle went through the placenta. All pregnancies were pro spectively evaluated through delivery. RESULTS: There were 13 losses a mong the 1000 procedures (1.3%). The transplacental losses occurred fr om 4 to 71 days after procedure, median 26.5 days; the nontransplacent al losses from 12 days after procedure to term, median 25 days. The lo ss rate was essentially similar in the two categories: six transplacen tal (1.96%) and seven nontransplacental (1%) (relative risk 1.52 [95% confidence limits 0.84 to 2.75], p = 0.23). If the three patients with elevated maternal serum cu-fetoprotein values were excluded from data analysis, the loss rates in the two groups were virtually identical ( relative risk 0.98 [95% confidence limits 0.38 to 2.54], p = 1.0000). CONCLUSION: Transplacental amniocentesis does not appear to increase t he fetal loss rate in the hands of experienced surgeons. Moreover, in view of the time span between amniocentesis and loss in both groups, a procedural cause seems questionable.