Transabdominal chorionic villus sampling at 9.5-12 weeks' gestation. Placental vascular resistance and fetal cardiovascular responses.

Pregnancies subjected to chorionic villus sampling (CVS) have been associated with transverse limb reduction defects. This study was designed to examine the possible fetal cardiovascular responses to transabdominal 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 evaluated 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 normal distribution analysis were performed, and statistical significance was set at P < or = .05. Fetal heart rate increased with 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 heart rate change was influenced by neither gestation nor placental vascular 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 findings. 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 findings remains unclear, given the fact that all the fetuses in this group of patients were normal. These responses may be secondary to various degrees of placental hemorrhage and may represent part of or the total fetal response to various degrees of fetal blood loss.(ABSTRACT TRUNCATED AT 250 WORDS)