A Summary of 406 Amniocenteses Performed within Montana for Prenatal Diagnosis of Fetal Defects

Abstract

In 1982, Shodair - Montana Regional Genetics Services began utilizing amniocentesis as a technique for prenatal diagnosis of fetal defects. Since that time, over 400 amniocenteses have been performed, and the results of 406 were reviewed. Amniocenteses were performed on individuals for three main reasons: 238 (56.3%) were performed because of advanced maternal age of 35 years or greater, with an average of 37.0 years (standard deviation of 3.14); 126 (29.80%) were performed due to maternal anxiety; finally the last indication for anmiocentesis to be performed is for a family history of or previous fetal abnormalities. This accounted for 45 (10.6%) of the total indications for the study. Of the 406 amniocenteses reviewed, the procedure was 100% effective in the determination of fetal sex. In 15 (3.69%) of the cases, the amniocentesis failed to detect congenital defects present in the fetus. Spontaneous fetal loss occurred in 6 (1.72%) of the cases. The procedure had to be repeated in 1.97% of the cases due to inadequate conditions of the initial amniotic fluid. The results of the amniocentesis were determined in an average of 16.7 days. Of the 406 cases, 14 showed genetic defects including: 1, 46 +21; 1, 46 +18; 2, 46 + markers; 2, 46XXY; along with 8 chromosomal rearrangements shown in Table 4. These chromosomal rearrangements included: 1, 46xy rep(l;12); 1, 46x inv(y); 1, 46xx inv(4); 1, 45xx+ (13;14); 1, 46xy +(6;13)p23, q22mat; 1, 45xy tdic (14;21); 45xx tdic (13;21).