Update on procedure-related risks for prenatal diagnosis techniques.

INTRODUCTION As a consequence of the introduction of effective screening methods, the number of invasive prenatal diagnostic procedures is steadily declining. The aim of this review is to summarize the risks related to these procedures. MATERIAL AND METHODS Review of the literature. RESULTS Data from randomised controlled trials as well as from systematic reviews and a large national registry study are consistent with a procedure-related miscarriage rate of 0.5-1.0% for amniocentesis as well as for chorionic villus sampling (CVS). In single-center studies performance may be remarkably good due to very skilled operators, but these figures cannot be used for general counselling. Amniocentesis performed prior to 15 weeks had a significantly higher miscarriage rate than CVS and mid-trimester amniocentesis, and also increased the risk of talipes equinovarus. Amniocentesis should therefore not be performed before 15 + 0 weeks' gestation. CVS on the other hand should not be performed before 10 weeks' gestation due to a possible increase in risk of limb reduction defects. DISCUSSION Experienced operators have a higher success rate and a lower complication rate. The decreasing number of prenatal invasive procedures calls for quality assurance and monitoring of operators' performance.