RESUMO
BACKGROUND: 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. OBJECTIVE: To evaluate the frequency of chromosomal abnormalities in 3081 amniocentesis performed in patients at high risk of having an affected child. MATERIALS AND METHODS: 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. RESULTS: 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%. CONCLUSIONS: Our data could be used to provide genetic counseling based on the experience reported here.
