Advanced maternal age as a sole indication for genetic amniocentesis; risk-benefit analysis based on a large database reflecting the current common practice.

AIMS

Recent advances in prenatal screening, including first and second trimester genetic screening as well as targeted sonography, have significantly improved the detection of trisomy 21. Therefore, several investigators have questioned the validity of recommending genetic amniocentesis to all women who are 35 years or older at delivery. Thus, we sought to investigate the risks and benefits associated with performing genetic amniocentesis in women whose sole indication for testing was advanced maternal age (AMA).

METHODS

A retrospective review of a Genzyme Genetics amniocentesis database (January 2006-December 2006) was performed. All specimens obtained from women of AMA as the sole indication were eligible for analysis. The amniocentesis-related potential fetal loss was calculated based on the traditional fetal loss rate of 1/200 as well as the recently published loss rate of 1/1600 procedures. Risk-benefit analysis was performed by comparing the number of trisomy 21 fetuses identified within the AMA group to the potential number of amniocentesis-related fetal losses within this group.

RESULTS

A total of 87,241 amniocentesis specimens were processed during the study period. AMA was the sole indication for genetic amniocentesis in 43,303 cases which formed the study group. In 399 (0.92%) of these cases, a trisomy 21 was identified. Assuming an amniocentesis related fetal loss rates of 1/200 or 1/1600; 217 or 27 fetal losses would have been expected, respectively.

CONCLUSIONS

Our analysis suggests that the benefit of genetic amniocentesis for the sole indication of AMA far outweighs the potential amniocentesis-related fetal loss rate, regardless of the actual rate one considers.