[Rapid karyotyping in the 2nd and 3rd trimester: results and experiences].

Rapid karyotyping in the second and third trimester is an increasing field of collaboration between women's hospitals and human genetics. Techniques available for rapid karyotyping are: 1. Amniocentesis; to obtain amniotic fluid cells for culturing and subsequent chromosome harvesting using the pipette method or the "in situ" technique. The average time between preparation of the amniotic fluid and the verbal notification of the analysed karyotype is 4.65 days for the pipette method and 5.97 days for the "in situ" technique. The major advantages are that amniocentesis can be handled safely by many gynaecologist, and the amniotic fluid samples can be posted easily to cytogenetic units familiar with rapid karyotyping. The main disadvantage is that currently only a few laboratories are able to handle the pipette method or the "in situ" technique for rapid karyotyping. 2. Fetal blood sampling (cordocentesis); and subsequent chromosome analysis on cultivated fetal lymphocytes leading to results within 2 to 4 days. The main advantage of this procedure is the reliability of the results obtained. Fetal blood sampling, however, is restricted to specialists; this may involve scheduling delays. 3. Placental biopsy; with subsequent direct preparation and long term culturing. In comparison to both other techniques this procedure is faster if direct preparation is used. Results can be obtained even on the same day. The main disadvantage, however, is the problem with the reliability of the direct preparation results. They must be confirmed by time-consuming long-term culturing. Data are presented on the likelihood of abnormal ultrasound findings being caused by chromosomal aberrations.(ABSTRACT TRUNCATED AT 250 WORDS)