Amniocentesis or chorionic villus sampling in multiple gestations? Experience with 500 cases.

Area of Science:

• Medical Genetics
• Obstetrics and Gynecology
• Prenatal Diagnostics

Background:

• Multiple pregnancies present unique challenges for prenatal diagnosis.
• Amniocentesis and chorionic villus (CV) sampling are common invasive procedures.
• Evaluating laboratory aspects and discordant results is crucial for patient management.

Purpose of the Study:

• To compare the laboratory aspects of amniocentesis and CV sampling in multiple pregnancies.
• To assess the frequency and consequences of discordant results between sampling methods.
• To determine the preferred method for prenatal diagnosis in multiple gestations.

Main Methods:

• Retrospective analysis of 500 women with multiple pregnancies undergoing amniocentesis or CV sampling (1988-1997).
• Evaluation of uncertain results, erroneous sampling, cross-contamination, and maternal cell contamination.
• Comparison of safety in selective fetal reduction post-sampling.

Main Results:

• Uncertain results were more frequent with CV sampling (5%) compared to amniotic fluid (AF) sampling (0.3%).
• Cross-contamination in CV samples occurred in 2 of 7 cases, but did not cause diagnostic dilemmas.
• Maternal cell contamination caused one diagnostic problem in AF samples.
• Selective fetal reduction appeared safer following CV sampling.

Conclusions:

• CV sampling, despite a higher rate of uncertain results, is now the preferred method for prenatal diagnosis in multiple pregnancies at our department.
• The benefits of CV sampling, including safer fetal reduction, outweigh the increased frequency of uncertain results.