TRANSABDOMINAL CHORIONIC VILLUS SAMPLING AT 9.5-22 WEEKS GESTATION - PLACENTAL VASCULAR-RESISTANCE AND FETAL CARDIOVASCULAR-RESPONSES

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.