Transplacental needle passage in early amniocentesis and pregnancy loss.

OBJECTIVE

To determine whether transplacental needle passage affects the frequency of pregnancy loss in early amniocentesis.

METHODS

We reviewed 380 consecutive cases of amniocentesis performed before 14.9 weeks' gestation because of advanced maternal age (at least 35 years old). Procedure and pregnancy outcome data were obtained from reviews of patients' charts and telephone contact with patients or referring physicians.

RESULTS

Transplacental needle passage occurred in 147 cases (38.7%). Pregnancy loss rates were similar in the transplacental and nontransplacental groups. Only the frequency of bloody taps was significantly increased among women undergoing early transplacental amniocentesis.

CONCLUSION

Transplacental needle passage in cases of amniocentesis performed before 14.9 weeks' gestation does not appear to increase the risk of pregnancy loss. Therefore, deferring early amniocentesis to a later time at which nontransplacental amniocentesis may be performed should be reserved only for cases complicated by placental vessels, placental vascular lacuna ("placental lakes"), or subchorionic hematomas that should not be traversed by a needle.