PGF and preeclampsia: The negative predictive value (NPV) of an sFlt-1/PlGF ratio ≤38 to rule out preeclampsia was 99.3% within 1 week and 94.3% within 4 weeks; the positive predictive value (PPV) to rule in preeclampsia within 4 weeks was 36.7% [17, 22, 23].