NPPB and hydrops fetalis: The most valuable findings can be summarized as follows: BNP concentrations ≥ 100 pg/mL yielded an average diagnostic accuracy of 83%, BNP values ≤50 pg/mL resulted in a negative predictive value of 96%, a cut-off value of 400 pg/mL indicated presence of HF, a cut-off value of 100 pg/mL indicated absence HF, and the gray zone is between 100–400 pg/mL [13].