Red blood cell parameters in antenatal nonsickling hemoglobinopathy screening

OBJECTIVE To find a hematological parameter and the cut-off level for identification of nonsickling hemoglobinopathies in pregnant women. MATERIALS AND METHODS Venous blood samples of 849 women with singleton pregnancies were collected at the first visit. All women who met inclusion criteria were examined for nonsickling hemoglobinopathy. On the basis of the sensitivity and the specificity of different cut-off levels for hematological parameters, we calculated the optimal clinically practicable parameter for screening of nonsickling hemoglobinopathies in pregnant women. RESULTS On the basis of the sensitivity and the specificity, the best screening parameters for the identification of nonsickling hemoglobinopathies among nonanemic pregnant women are mean corpuscular volume (MCV) with cut-off ≤80 fL (Youden's index 91.2%), mean corpuscular hemoglobin (MCH) <27.5 pg (Youden's index 90.7%), and microcytosis (MRC) ≥3% (Youden's index 90.2%). An analysis using receiver operating characteristic curves and the calculated Youden's index showed that MCV ≤76 fL, MCH ≤24 pg, or MRC ≥10% are the best red blood cell indices for the screening of nonsickling hemoglobinopathy among anemic women with iron deficiency. CONCLUSION Our results suggest targeted screening for nonsickling hemoglobinopathies in nonanemic pregnant women with MCV ≤80 fL, MCH ≤27.5 pg, or MRC ≥3% and in anemic women with MCV ≤76 fL, MCH ≤24 pg, or MRC ≥10%.