Amniotic fluid fibrinogen degradation products in the prenatal diagnosis of neural tube defects.

Elevated levels of fibrin(ogen) degradation products (FDP) have been detected in second-trimester amniotic fluid in association with open neural tube defects (NTD'S) in the fetus. The FDP assay has been proposed for the prenatal diagnosis of NTD's and in this paper is compared with the established use of the alpha-fetoprotein (AFP) assay. FDP and AFP levels were measured in 132 amniotic fluid samples, including 20 NTD cases. The false negative and false positive rates for the FDP assay are high compared with the AFP assay, but it may be of value as an adjunct assay to reduce the over-all false positive rate.