[Report on 8 years' experience in prenatal diagnosis of genetic defects. I. Indications and methods]

Prenatal diagnostic procedures were done following 1231 transabdominal amniocenteses in 1113 patients of a gestational age of 17.4 +/- 0.5 weeks. Partly parallel the following methods were used: 1218 estimations of alpha-fetoprotein, 903 chromosomal analyses, 89 amniofetographies, 40 fetoscopies and 7 estaminations of hormones, immunoglobulins and enzymes. Amniotic fluid could be obtained in 91.8 per cent with the first insertion of the needle, using the free-hand-needle-technique. In 8 per cent amniotic fluid samples were bloody. The amniocentesis had to be repeated in 7.6 per cent because of no growth of cells (6.3 per cent), or no amniotic fluid could be obtained (1.3 percent). In the average 14.9 +/- 8.1 metaphases were analysed and 2.9 +/- 1.1 karyogram were made. The organisation of prenatal diagnostics was explained. The indication was in 39.6 per cent the age, in 20.3 per cent the repeated risk of the birth of a fetus with trisomy 21. In 13.7 per cent there was an indication to estimate alpha-fetoprotein which was done nearly without exception for exclusion of neural tube defects. The prenatal determination of the fetal sex was necessary in 7.3 per cent in cases of X-chromosomal inheritable diseases. Previous deliveries of infants with malformation-syndrome or chromosomal trisomies like Edwards-or Patau-syndrome and radiation or chemotherapy of one of the parents were summarized under other indications (7.3 per cent). Balanced parental translocations were the indication in 1.7 per cent. Amniofetography was used in 8 per cent of the patients to exclude malformations caused by prevalent multiple factors. It was in 35 per cent the prevailing diagnostic method. The set of problems of its use was discussed. Fetoscopy (3.6 per cent) partly was an additional diagnostic procedure partly a leading method. By means of a catalogue of indications it was referred to the use of fetoscopy to visualization in prenatal diagnostics. The exclusion of genetic metabolic defects was the motive to prenatal biochemic investigations in 0.5 per cent. The prerequisites of devices and technique to prenatal diagnostics were discussed.