Cariotipos fetales mediante amniocentesis y cordocentesis en Costa Rica

objective: the identification of fetal abnormal chromosomes to allow proper pediatric and obstetric management of the cases as well as genetic counseling. material and methods: the results of 290 genetic amniocentesis from january 2000 to august 2003, are reported. there were two main reasons for referral: abnormal ultrasound assessment (44% of cases) and advanced maternal age (39%). most procedures (91%) were performed during the second trimester of pregnancy. fetal cells were closed cultured and suspension harvested. turn around time was 16 days median. g banded (300-400 bands resolution) chromosomes from 20 cells provided by two independent cultures were karyotyped in each case. the results of 18 genetic percutaneous umbilical cord samplings from january 2002 to august 2003, are also reported. almost all procedures were performed due to abnormal ultrasound findings from gestational week 17 to 35. results: in 230 fetal karyotypes obtained from amniotic fluid, 27 (12%) were abnormal, due to 12 autosomal trisomies , three cases of monosomy x, three mosaics involving chromosome x, three triploid karyotypes, two balanced translocations of maternal origin, one structurally abnormal chromosome and three other defects of sexual chromosomes in males. prenatal cytogenetic and sonographic findings correlated with the fetal or newborn phenotype in all cases available for follow-up. fetal abnormal chromosomes obtained from fetal blood were: two cases of trisomy 13, one fetus with trisomy 18, and one case of trisomy 21. conclusion: chromosome defects are an important reason for ultrasonographic fetal abnormalities and adverse pregnancy outcomes. normal results provided reassurance to the parents.