Fibrin/Fibrinogen Degradation Products in Amniotic Fluid

Fibrin/fibrinogen degradation products (F. D. P.) have been studied in amniotic fluid from normal pregnancies and in pregnancies complicated by hypertension, anencephaly, and hydramnios without foetal anomaly.

Using the haemagglutination inhibition immunoassay, F. D. P. were identified in 51 of 53 (mean 3.75 mcg/ml, S.D.±2.80) samples of amniotic fluid from healthy patients with normal pregnancies between 14 and 40 weeks gestation. In the hypertensive group of 16 patients the mean F. D. P. level of 5.00 mcg/ml (S.D.±3.25), was not significantly different from the normal group. In 7 patients with anencephalic foetuses the amniotic fluid F. D. P. level was significantly elevated (mean 17.5 mcg/ml, S.D.±5.75), while in 6 patients with hydramnios without foetal anomaly the F. D. P. level (mean 6.00 mcg/ml ±3.25) was not significantly different from the normal group.

Characterization of the amniotic fluid F. D. P. was carried out using double immunodiffusion polyacrylamide gel electrophoresis, and gel filtration on Sephadex G-200. The F. D. P. were present in two distinct components. The major fraction was fragment X (M. W. 240,000) and in a lower concentration, fragment D was identified.

The detection of raised amniotic fluid F. D. P. levels in early pregnancy may provide a diagnostic test for open central nervous system foetal abnormalities.