Tracy B. Perry

Fetoscopy and fetal blood sampling: A percutaneous approach☆☆☆

Abstract A technique of fetoscopy is described which is performed percutaneously under local anesthesia. A cannula has been developed that allows the sampling of fetal blood. Direct visualization of the fetus and further sampling of its environment now seem possible but must await extensive study of safety prior to clinical use.

Fetal cephalometry by ultrasound as a screening procedure for the prenatal detection of Down's syndrome

Infants and children with Downs syndrome have a cephalic index (ratio of biparietal to occipitofrontal diameter) higher than that in normal children. To determine whether this difference is present and detectable by ultrasound measurement of the second‐trimester fetal head, we calculated the cephalic indices for 308 normal fetuses and eight fetuses with a 47,+21 karyotype. The mean cephalic index in the fetuses with Downs syndrome (0.829, SD 0.033) was indistinguishable from that in the normal fetuses (0.825, SD 0.042). These data suggest that the documented difference in mean cephalic index between liveborn children with Downs syndrome and normal control children is not detectable in the mid‐gestation fetus and that ultrasound cephalometry alone is unlikely to discriminate reliably between normal and affected fetuses.

Amniophoresis as an adjunct to fetoscopy

Abstract Described is a technique for separating red blood cells from amniotic fluid via a continuous flow cell separator. The term “amniophoresis” has been coined to describe this process, which is used during fetoscopy to restore a clear view subsequent to puncture of the placenta. Short-term and long-term risks to the fetus from the second uterine puncture, dilution of amniotic fluid, and removal of normal cellular components are yet to be assessed.

Chorionic Villi Sampling: The McGill Randomized Clinical Trial of Safety and Accuracy

The use of chorionic villi sampling (CVS) has increased dramatically during the 2 years since the initial reports in the Western literature of this approach to first trimester prenatal diagnosis (Kazy et al. 1982; Old et al. 1982). At least 3000 diagnostic cases have already been evaluated worldwide (Jackson and Wapner 1984), and many new centers are considering the use of this technique to advance prenatal diagnosis from the second to the first trimester. Although it appears that the spontaneous abortion rate in women who have had CVS is low in centers with the greatest experience with the procedure (Jackson and Wapner 1984), there has as yet been no study to compare pregnancy outcomes in women having diagnostic CVS with those in women having amniocentesis. To examine systematically the questions of the safety and accuracy of CVS, we have designed and implemented a randomized clinical trial of CVS and amniocentesis. This study has been approved by the clinical ethics committees at the hospitals involved. The purpose of this communication is to outline the design of our study and to discuss some of the problems we have encountered. We do not analyze pregnancy outcome data here because this would invalidate use of the data at the end of the study.