Pregnancies subjected to chorionic villus sampling (CVS) have been ass
ociated with transverse limb reduction defects. This study was designe
d to examine the possible fetal cardiovascular responses to transabdom
inal CVS. We examined 42 patients referred for CVS between 9.5 and 12
weeks' gestation. CVS was performed transabdominally under ultrasonic
guidance with a 20-gauge needle. Placental vascular resistance was eva
luated by means of the umbilical artery pulsatility index. Fetal heart
rate was ascertained automatically from two successive flow velocity
waveforms. Paired t test, regression analysis, power analysis and norm
al distribution analysis were performed, and statistical significance
was set at P less than or equal to .05. Fetal heart rate increased wit
h increasing amounts of tissue, but placental vascular resistance did
not change. The earlier the gestation, the larger the amount of tissue
obtained. Multiple regression analysis demonstrated that the fetal he
art rate change teas influenced by neither gestation nor placental vas
cular resistance after CVS. Analysis of the change (difference before
and after CVS) in placental resistance and fetal heart rate according
to gestational age and amount of tissue did not change the above findi
ngs. Although statistically significant fetal cardiovascular responses
can be elicited in relation to the amount of chorionic villi obtained
during transabdominal CVS, the clinical significance of these finding
s remains unclear, given the fact that ail the fetuses in this group o
f patients were normal. These responses may be secondary to various de
grees of placental hemorrhage and may represent part of or the total f
etal response to various degrees of fetal blood loss. Although these r
esponses do not seem to be clinically significant, it is advisable to
obtain the minimum necessary amount of tissue with the smallest degree
of damage to the placenta until further studies prove transabdominal
CVS to be safe.