DOES CHORIONIC VILLUS SAMPLING COMPROMISE FETAL UMBILICAL BLOOD-FLOW

A possible association of limb reduction defects with chorionic villus sampling (CVS) may be related to compromised umbilical blood flow fro m the trauma of the procedure. We hypothesized that because CVS may di srupt or compromise umbilical blood flow to the fetus, either by vasoc onstriction, bradycardia, or emboli, we would detect these changes usi ng Doppler velocimetry. A cohort of 21 consecutive consenting patients undergoing first-trimester elective CVS for prenatal diagnosis were e ntered into a prospective longitudinal study. Colour flow Doppler velo cimetry was performed on fetal umbilical arterial blood flow immediate ly before and after CVS to measure the pulsatility index, fetal heart rate, per cent how time, and maximum flow velocity. Measurements were obtained from three consecutive cardiac cycles in three different umbi lical segments and averaged. Potentially confounding variables also re corded included gestational age, method of CVS, number of passes, numb er of aspirations, placental location, tissue sample size, and operato r. Umbilical velocimetry values before and after CVS were compared usi ng the paired t-test and showed no statistically significant differenc es. No differences were found when data were analysed by gestational a ge, sample size, method, number of aspirations, placental location, or operator. We were unable to detect any significant change in fetal um bilical arterial blood flow velocimetry or heart rate after performing CVS. Umbilical blood flow does not appear to be routinely compromised by CVS.