The effect of cordocentesis on umbilical and middle cerebral artery blood flow velocity waveforms

Abstract

Objective To investigate the effect of cordocentesis on the umbilical and fetal cerebral circulation. Design Cross sectional study. Setting Department of Obstetrics and Gynaecology, Regional Referral Centre for Fetal Medicine, Klagenfurt Hospital, Austria. Subjects Thirty pregnant women undergoing diagnostic cordocentesis at 18 to 38 weeks' gestation. Interventions The pulsatility index (PI) in the umbilical artery and fetal middle cerebral artery was measured by pulsed Doppler ultrasound before and immediately after cordocentesis. Main outcome measures Change in umbilical artery PI and middle cerebral artery PI. Results Cordocentesis was associated with a significant decrease in both umbilical artery PI (median −0.18, range −2.21 to 1.5, P<0.004) and middle cerebral artery PI (mean ‐0.15, SD 0.32, P<0.03) and the decrease in umbilical artery PI was most marked when cordocentesis was performed transplacentally. In four cases, there were absent or reversed frequencies at the end of diastole (EDF) in the umbilical artery before cordocentesis, and in all cases there were positive EDF after the procedure. In contrast, one of the 26 cases with positive EDF developed reversed EDF following the procedure. Conclusions Acute alterations in the waveforms from both the umbilical and fetal cerebral circulation can be induced by cordocentesis. The decrease in resistance in the fetoplacental circulation could be attributed to the release of vasodilators, and the increase in resistance observed in some cases could be secondary to arterial vasospasm. Better understanding of the underlying mechanisms might help in making cordocentesis a safer procedure.

Changes in Blood Flow Velocity Waveforms following Fetal Blood Sampling

“…In one study [10], the largest changes in Pis occurred in fetuses with high values before the procedure, i.e. those more likely to be hypoxemic/acidemic, whereas in another series [9], fetuses with low pC>2 and pH values showed the least changes following blood sampling.…”

“…Decreased vascular resistance in the um bilical artery, as assessed by Doppler analysis of velocity waveforms, has already been re ported to be an immediate effect of fetal blood sampling [8][9][10].…”

“…The mechanisms by which some complications occur often remain elusive, es pecially in the absence of abnormal findings upon histologic examination of the cord [7], Doppler investigation of blood flow in dif ferent fetal districts is used widely in an attempt to discriminate between transient, 'benign', and persistent, 'ominous' bradycar dias which may follow fetal blood sampling. However, even with uncomplicated proce dures, acute changes in umbilical artery [8][9][10] and middle cerebral artery [10] velocity waveforms have been reported. To what ex tent these changes are related to the needle puncture, the removal of blood volume, the fetal conditions, and the site of sampling has not been assessed comprehensively.…”

Effects of Cordocentesis on Inferior Vena cava Velocity Waveforms: Differences between Normally Grown and Growth-Retarded Fetuses

“…A modification of afterload seems unlikely since cordocentesis induces a decrease in pe ripheral vascular resistances rather than an increase [3][4][5][6]. Similarly, a primary change in myocardial compliance seems unlikely due to the short time interval considered in the ex perimental design.…”

“…Indeed cordocentesis causes a decrease in im pedance to flow at the level of the umbilical artery [3][4][5] and fetal peripheral vessels [5,6] associated with an increase in the systolic/ atrial ratio from ductus venosus, suggestive of an enhanced venous return to the heart [7], As a consequence of these hemodynamic changes in.peripheral circulation peak velocity value from outflow tracts and Doppler estimated cardiac output increase [8], Moreover, in growth-retarded (IUGR) fetuses the peripher al hemodynamic responses to cordocentesis are less marked [5,7] and associated with the absence of modifications or a reduction in cardiac flows [8],…”