Between September 1st 1990 and Juli 31st 1993, 5071 pregnant women were screened 
prospectively by the "triple-test", including maternal serum alpha-fetoprotein, 
human chorionic gonadotropin and unconjugated oestriol in order to detect 
chromosomal anomalies and open neural tube defects. The serum samples were 
collected in collaboration with the obstetricians of the region of 
West-Mecklenburg and North-West-Brandenburg. Laboratory testing using 
radioimmunoassays was performed between weeks 15 and 20 of gestation, all serum 
specimens being investigated in only one institution. The original 
alpha-software from Wald et al. was the basis for calculating the statistical 
risk for Down's syndrome. Pregnant women with a high risk for Down's syndrome 
(cutoff > or = 1:250) were taken care of in a special outpatient clinic 
including procedures like amniocentesis and fetal blood sampling. Amongst 5071 
pregnant women, 21 fetal anomalies were seen. Five cases of Down's syndrome, 
three of trisomy 18, one trisomy 13, two cases of triploidy and four cases of 
open neural tube defects, one 46 xy/45 x mosaic karyotype and one case of 
gastroschisis could be diagnosed correctly. One case of trisomy 21, one case of 
trisomy 18 and two open neural tube defects showed false negative results. Using 
the cutoff of 1:250 for prenatal detection of Down's syndrome and performing 
ultrasound routinely to determine gestational age, the sensitivity of the 
"triple-test" was 83.33% having a specificity of 92.68%. The predictive value of 
a positive test for prenatal diagnosis of Down's syndrome was 1.33%.(ABSTRACT 
TRUNCATED AT 250 WORDS)