[Amniocentesis to study the fetal karyotype before 16 weeks of amenorrhea. Prospective study comparing it with...

In a prospective study, we compared early amniocentesis (13-15 weeks of amenorrhea, n = 67) with conventional amniocentesis (16-20 weeks, n = 105). Early amniocentesis was not associated with complications and cell culture was possible in every case. Sampling failures were more frequent (4.5% vs 0.9%, p = 0.057), but had no deleterious effects and this rate can probably be reduced with experience. The mean time required for karyotyping was only slightly longer: 17.0 (SD 2.8) days vs 15.8 (SD 2.0) days (p < 0.01). These results agree with other recent studies suggesting that early amniocentesis is a simple and safe method which can be performed several weeks before conventional amniocentesis.