[Amniocentesis versus choriocentesis (chorionic villi sampling) and cordocentesis (fetal blood sampling)]

Opinions are still divergent regarding the respective place of amniocentesis and choriocentesis in the scheduled prenatal diagnosis. Amniocentesis (PLA) is the oldest method. This technique is perfectly mastered as well as its results, complications; its follow-up is 17-18 years in the world and over 16 years in Lyon. The rate of technical failures is inferior to 0.5 p. cent under ultrasonographic control. Its results are quite reliable (one error in 4 to 5,000 amniocentesis for the karyotype). The culture failures are under 1 p. cent. The titration of tracers, such as alpha-feto-protein or acetyl-cholinesterase is possible, favoring PLA over choriocentesis when there is a risk of neural dysraphias. PLA may be performed at any time during the pregnancy. Its main drawback seems to be its lateness: currently, the ideal time is 15-16 weeks. PLA performed earlier may result in more technical and culture failures. When performed at 12-13 weeks, it enters in competition with the choriocentesis although its theoretical risk of abortion is lower. Therefore, PLA and choriocentesis may be competitors, according to the risk factors and the indications, especially regarding cytogenetics.