[The alpha-fetoprotein level analysis in open neural tube defects and chromosomal aberrations in the fetus]

During the last 12 years 4258 amniocenteses were performed between the 12th and 20th week of gestation (including 323 early amniocenteses carried out before 15th week). In every case, cytogenetical examination was performed and concentration of AFP was determined. In cases with elevated AFP level electrophoresis of AchE izoenzymes was performed. The results of the tests enabled us to calculate laboratory standard values of AFP in the amniotic fluid for 12th to 20th weeks of gestation. In 22 of 44 pregnancies with Down's syndrome the value of AFP concentration was below the 25th percentile of the laboratory normal value. In 5 of 10 pregnancies with Edward's syndrome AFP level exceeded significantly the 75th percentile of the laboratory norm. In two cases it was due to coexisting spina bifida and in one case due to omphalocele. In 28 amniotic fluid samples AFP concentration exceeded normal level and electrophoresis of AchE revealed additional band. In 26 cases increased values of AFP were due to open neural tube defect in the fetus: 13 cases of anencephaly and 13 cases of spina bifida; in the remaining two other cases omphalocele was found.