Prenatal diagnosis of chromosomal abnormalities by amniocentesis: report of 261 cases

Amniocentesis is a technique for detection of chromosomal abnormalities in the unborn fetuses. The technique is being applied to the all high risk pregnancies, mostly in advanced maternal ages and abnormal results in the 1st or 2nd trimester pregnancies. In current situation, first trimester screening is being done in the 11 to 13 weeks and 6 days of gestation, and mid-trimester screening (between weeks 15 to 20). We report the result of our samples in this article. 261 pregnancies were followed and screened by 1st and 2nd trimester screening by Iranian Fetal Foundation protocols in an 18 months period (from January 2007 to July 2008). Advanced maternal ages (35 years and more), or detected a balanced structural chromosomal abnormalities in one of the parents were indications for amniocentesis in this group. Amniocentesis was performed in the 261 cases during the mentioned period. In all of the culture tubes (100%) cell growth was successful. Mean of the time for screening and reporting the results was 12 days. Twelve affected fetuses (4.6%) were detected. The most common abnormalities were Down’s syndrome and balanced translocation. First and second trimester screening is recommended to all pregnancies by international FMF protocol. Whenever the results showed that the pregnancy is prone to the risk then amniocentesis is highly recommended to detect chromosomal abnormalities.