Correlation between indication for amniocentesis and the time of its performing

Prenatal diagnosis of fetal disorders is a very wide range of noninvasive and invasive methods. We use ultrasound examination and biochemical tests as screening tools in the low risk pregnancies. In a high risk pregnancy we perform invasive procedures to obtain definitive diagnosis. Amniocentesis is carried out in the first or in the early second trimester of pregnancy to determine: fetal karyotype, monogenic disorders, metabolic errors, the level of alpha-fetoprotein and acetylocholinesterase.

The aim of our study was to determine the impact of the indication to amniocentesis on the time of performing the procedure.

We have analysed all the 721 amniocenteses carried out in the Department of Obstetrics in Gdansk in 1996-2002. Amniocenteses were performed due to: advanced maternal age in 553 cases, fetal malformation in current pregnancy in 39 cases, inherited disease in previous pregnancies in 80 cases, maternal balanced translocation in 6 cases, psychological reasons in 15 cases, inherited diseases in the family in 8 cases and serious obstetric history in 9 cases, abnormal results of triple test in 11 cases. The T-Student test was used for statistical analysis with the significance level p=0.05.

The amniocentesis was performed in the 15th (from the 12th to the 26th) week of gestation. Amniocentesis performed because of: advanced maternal age in the 15th (from the 12th to the 25th); foetal malformation in current pregnancy in the 16th (from the 12th to the 26th); inherited disease in previous pregnancies in the 14th (from the 12th to the 18th); maternal balanced translocation in the 13th (from the 13th to the 14th); psychological reasons in the 15th (from the 13th to the 18th); inherited diseases in the family in the 15th (from the 13th to the 22nd); serious obstetric history in the 16th (from the 15th to the 17th); abnormal results of triple test in the 16th (from the 14th to the 19th). There is a statistical difference between time of performing amniocentesis because of advanced maternal age, fetal malformation in current pregnancy, maternal balanced translocation and other indications.

In pregnancies with serious obstetric history--balanced translocation, inherited disease in previous pregnancies--women decided to perform amniocentesis earlier than in cases when advanced maternal age was the only indication for this procedure.