The effects of fetal blood sampling and placental puncture on umbilical artery and fetal arterial vessels blood flow velocity waveforms.

This study was performed to investigate whether fetal blood sampling and/or transplacental puncture are associated with changes of blood flow velocity waveforms in umbilical artery and fetal circulation. The pulsatility index (PI) was measured from umbilical artery, thoracic descending aorta, renal artery, and middle cerebral artery immediately before and after fetal blood sampling (n = 28) or third trimester amniocentesis (n = 32). No significant changes in PI values were evidenced after amniocentesis performed either transamniotically (n = 21) or transplacentally (n = 11). Fetal blood sampling induced a significant decrease of PI values in all the vessels investigated. However, in presence of a transplacental procedure (n = 15) the amplitude of the decrease of PI in umbilical artery was significantly higher than after a transamniotic procedure (n = 13), while no differences were evidenced in the other vessels tested. These findings indicate that umbilical cord puncture at the time of fetal blood sampling is associated with a decrease in PI in umbilical artery and several peripheral arterial vessels. The isolated placental puncture does not induce Doppler-detectable hemodynamic effects, while in conjunction with cord needling, it increases the amplitude of the effects in umbilical artery.