Acute hemodynamic effects induced by chorionic villus sampling: a preliminary investigation

Chorionic villus sampling significantly affects fetal cardiovascular function

OBJECTIVE

To assess the effects of chorionic villus sampling (CVS) on fetal heart rate (FHR).

METHODS

A prospective longitudinal study was conducted among 300 patients undergoing transabdominal CVS between 8 and 13 weeks of gestation. Duration of the procedure, number of needle passes, sample weight, maternal age, fetal gender, and FHR response to CVS were recorded.

RESULTS

The FHR before but not after CVS was inversely correlated with gestational age (r = -0.406, p < 0.001). Conversely, following CVS, no correlation was observed between FHR and gestational age (r = -0.06, p = 0.27). The difference between FHR after CVS and that obtained before CVS (delta FHR) increased with increasing gestational age at sampling (r = 0.372, p < 0.0001), decreased with increasing specimen weight (r = -0.16, p = 0.01) and increased with increasing maternal age (r = 0.22, p < 0.0001). Duration of the procedure, fetal gender and number of needle passes did not affect delta FHR. Multiple logistic regression indicated that gestational age at CVS and maternal age but not the other variables significantly affected delta FHR and together they accounted for over 22% of the variance (R(2) = 0.224, p < 0.0001).

CONCLUSIONS

In summary, our results suggest that acute fetal hemodynamic changes accompany CVS and that these changes vary with gestational age.

The Effect of Chorionic Villus Sampling on Fetal Heart Rate

OBJECTIVE

Fetal heart rate (FHR) variation during chorionic villus sampling (CVS) is a controversial topic. Limited studies have been published on this subject. Our study intended to evaluate the effects of CVS on the FHR.

METHOD

One hundred and sixty-five patients undergoing first-trimester elective CVS for prenatal diagnosis of beta-thalassemia were entered into a prospective study. M-mode FHR was obtained before and immediately after CVS in the patients. Potentially confounding variables also recorded included: gestational age, number of needle passes and placental location.

RESULTS

FHR values before and after CVS were compared using the paired t test and showed no statistically significant differences by 95% confidence. No differences were found in data analyzing gestational age, number of needle passes or placental location.

CONCLUSION

We were unable to detect any significant change in FHR after performing CVS. It seems that FHR is generally not altered by CVS.

Invasive diagnostic procedures in twin pregnancies

The rising rate of multiple pregnancies and its association with advanced maternal age has expanded the need for prenatal diagnosis in twins and higher order gestations. The complexity of the invasive diagnostic procedures and the risk of loss of an unaffected twin raise significant clinical, technical and ethical issues. In this review we discuss the specific issues of early scanning, counseling and determination of chorionicity prior to invasive procedures in twins. We present the available data describing the risk associated with these procedures in twins and compare data of fetal loss rate from different studies. We also discuss the issues of fetal blood sampling and late karyotyping in twin pregnancies.

Transient bradycardia in a mouse model for the oromandibulofacial limb hypogenesis syndrome following chorionic villus sampling

Amniotic sac puncture carried out on day 13 mouse embryos induces a high incidence of craniofacial and limb abnormalities that resemble the anomalies seen in the oromandibulofacial limb hypogenesis syndrome occasionally encountered following chorionic villus sampling carried out during early human pregnancy. It has been hypothesized that this syndrome probably has a vascular basis, possibly due to hypotension and hypoperfusion of tissues secondary to placental trauma, though no detailed aetiology has so far been described. We have determined embryonic heart rates in control embryos, in embryos at intervals following anaesthesia, and following amniotic sac puncture. An increased duration of bradycardia is seen following this procedure which is not observed in anaesthetic-only controls and in embryos in the contralateral (non-operated) uterine horns. We discuss why the incidence of oromandibulofacial limb hypogenesis syndrome is low following chorionic villus sampling, and propose a possible aetiology for the limb abnormalities seen in this condition.

Immediate changes in umbilical blood flow after transcervical chorionic villus sampling performed by biopsy forceps

Transvaginal ultrasonography with colour Doppler was used to evaluate the immediate changes on the fetal heart rate (FHR) and the fetal umbilical artery pulsatility index (PI) after chorionic villus sampling (CVS). This prospective study included 279 consecutive singleton pregnancies, between 10 and 13 weeks, of women who underwent transcervical CVS in our institution. All Doppler measurements were obtained transvaginally before and immediately after CVS. Structural malformations detected by ultrasound were excluded. Student's t- and Wilcoxon texts were performed for statistical analysis. The results showed no significant decrease in FHR (mean 1.04 beats, t = 1.68, P = 0.94) and a significant elevation of umbilical artery PI (mean 0.12, t = - 6.51, P < 0.001) post-CVS. This difference was only significant in procedures performed at less than 11 weeks' gestation, since there was no significant change for those procedures performed thereafter. These preliminary data suggest that acute fetal haemodynamic changes are induced by CVS and may have clinical effects. Hypotheses on possible vascular mechanisms are discussed. Colour Doppler could widen the possibilities for more accurate in vivo assessment and research on CVS-related placental injury.

Doppler assessment of umbilical flow after genetic amniocentesis

The aim of our study was to evaluate the immediate changes on the fetal heart rate (FHR) and the fetal umbilical artery pulsatility index (UPI) after performing genetic amniocentesis. This was a prospective study including 431 consecutive singleton pregnancies between 14 and 18 weeks undergoing genetic amniocentesis in our institution. Doppler measurements were obtained transabdominally before and immediately after the procedure. Structural malformations detected by ultrasound were excluded. Student's t-test was performed for comparisons among different groups and observed mean changes. The results showed a significant decrease in FHR post-amniocentesis (mean 1.5 beats, t = 3.47, P < 0.01) and a non-significant elevation in UPI (mean -0.01, t = -0.29, P = 0.77) after the procedure. Differences in FHR could be found when analyzed by each gestational week. These preliminary data suggest that although acute fetal hemodynamic changes are detected after genetic amniocentesis, such changes are unlikely to have clinical relevance. However, it is reasonable to propose the use of Doppler as a method of assessing hemodynamic effects caused by prenatal invasive procedures in order to provide more accurate in vivo research on this issue.

Fetal ductus venosus flow velocity waveforms and maternal serum AFP before and after first-trimester transabdominal chorionic villus sampling

Doppler flow velocity waveform recording in the fetal ductus venosus and umbilical artery as well as maternal blood sampling for serum alpha-fetoprotein (MSAFP) was performed before and after transabdominal chorion villus sampling (TACVS) in 36 women of advanced maternal age (> or = 36 years). Gestational age ranged between 11 and 13 weeks. No chromosomal anomaly was detected. No statistically significant difference was observed in ductus venosus velocity parameters or in the umbilical artery pulsatility index (PI) before and after CVS in 35 women with a normal pregnancy outcome. One case resulted in fetal loss. Post-CVS median MSAFP levels at 12 weeks (25 kIU/l) and 13 weeks (35 kIU/l) were significantly higher than pre-CVS levels. In three cases, post-CVS MSAFP levels were higher than 600 kIU/l, correlating with feto-maternal transfusions of approximately 1.0-1.4 ml, i.e., of around 40 per cent of feto-placental blood volume. One of these cases displayed absence of fetal peripheral blood flow velocities and fetal bradycardia following TACVS, resulting in fetal loss 1 week later. The remaining two cases had a normal pregnancy outcome, but showed a more than 50 per cent reduction in ductus venosus velocity after TACVS, whereas umbilical artery PI remained unchanged. However, similar velocity changes were associated with only small feto-maternal transfusions. Umbilical artery PI values remained unchanged.

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 from the trauma of the procedure. We hypothesized that because CVS may disrupt or compromise umbilical blood flow to the fetus, either by vasoconstriction, bradycardia, or emboli, we would detect these changes using Doppler velocimetry. A cohort of 21 consecutive consenting patients undergoing first-trimester elective CVS for prenatal diagnosis were entered into a prospective longitudinal study. Colour flow Doppler velocimetry was performed on fetal umbilical arterial blood flow immediately before and after CVS to measure the pulsatility index, fetal heart rate, per cent flow time, and maximum flow velocity. Measurements were obtained from three consecutive cardiac cycles in three different umbilical segments and averaged. Potentially confounding variables also recorded included gestational age, method of CVS, number of passes, number of aspirations, placental location, tissue sample size, and operator. Umbilical velocimetry values before and after CVS were compared using the paired t-test and showed no statistically significant differences. No differences were found when data were analysed by gestational age, sample size, method, number of aspirations, placental location, or operator. We were unable to detect any significant change in fetal umbilical arterial blood flow velocimetry or heart rate after performing CVS. Umbilical blood flow does not appear to be routinely compromised by CVS.