[Genetic amniocentesis in high-risk populations. Experience in 3081 cases]

Prenatal diagnosis is an advantage for couples with certain lifestyles, ensures self-determination of an affected child or procreate a healthy. However, Mexico has been performed only in private hospitals and the National Medical Center November 20 ISSSTE and the National Institute of Perinatology.

To evaluate the frequency of chromosomal abnormalities in 3081 amniocentesis performed in patients at high risk of having an affected child.

we analyzed the results of amniocentesis performed between September 1987 and August 2006. Data analysis was done using frequency tables and chi-square, Yates corrected and Mantel-Haenzel.

Most studies were requested by maternal age, maternal distress and positive biochemical marker. 9% (< or = 14 weeks) were early amniocentesis and 91% regular (> or = 15 weeks). The samples were processed in triplicate in an open cultivation system. The fetal karyotype was obtained in 99.9% of the studies, 10.5 +/- 1.4 days. Chromosomal abnormalities were detected in 128 cases (4.2%), 103 were unbalanced and 25 balanced. The most frequent abnormalities were: Down syndrome 39%, balanced translocations 13.2%, 12.5% of Edwards syndrome, alterations in sex chromosomes and 11.5% unbalanced structural aberrations 7%.

Our data could be used to provide genetic counseling based on the experience reported here.