Umbilical artery Doppler flow velocity waveforms after transplacental amniocentesis

To assess the influence of transplacental versus nontransplacental needle passage during genetic amniocentesis on umbilical artery (UA) pulsatility index (PI) and fetal heart rate (FHR).

Genetic amniocentesis was performed in 205 women with no major fetal malformations detected by prenatal ultrasound at a median gestational age of 14 weeks and 3 days (range 13 weeks and 1 day to 18 weeks and 6 days). Chromosomal abnormalities were observed in five fetuses. These pregnancies were excluded from further analyses. The study group consisted of 56 of the remaining 200 women in whom amniocentesis had been performed transplacentally. As controls two patients with nontransplacental needle passage were chosen for each woman in the study group, matched for gestational age (+/- 3 days) and as far as possible for the indication for amniocentesis. The UA PI and the FHR were measured immediately before and after the amniocentesis.

Amniocentesis did not cause significant changes in UA PI and FHR within or between the two groups. Division of the study population into three subgroups dependent on gestational age did not alter the results. Pregnancy outcome was similar in the two groups.

Transplacental needle passage during amniocentesis did not induce any changes in UA PI or FHR relative to a group with nontransplacental amniocentesis.