Initiating a chorionic villus sampling program. Relying on placental location as the primary determinant of the sampling route.

In initiating a chorionic villus sampling (CVS) protocol, we relied upon placental location as the determinant in the choice of technique. An anterior or fundal location prompted a transabdominal (TA) CVS, while the transcervical (TC) approach was reserved for posterior placentas. Using placental location to determine the choice of CVS technique appears to be feasible and may be associated with a lower failure rate during a facility's initial experience. Trials comparing the safety of these two methods should consider placental location an independent variable before randomization