Combined use of the cardiofemoral index and middle cerebral artery Doppler velocimetry for the prediction of fetal anemia.

OBJECTIVE

To assess the accuracy of the combined use of the cardiofemoral index (CFI) and the middle cerebral artery peak systolic velocity (MCA-PSV), converted to multiples of the median (MoM), as noninvasive means to detect severe fetal anemia.

METHOD

We measured CFI and MCA-PSV MoM in 37 fetuses just before their first (n=37), second (n=22), and third (n=14) cordocenteses and transfusions. Then, using 2 different criteria for severe fetal anemia detection (Hb deficit ≥7 g/dL and hemoglobin level ≤0.55 of MoM), we assessed their hemoglobin status during cordocentesis and the accuracy of CFI and MCA-PVS was determined.

RESULTS

At the first cordocentesis the mean hemoglobin level was 8.5±3.6 g/dL and 15 fetuses (40.5%) had hydrops. In a total of 81 fetal evaluations, 58 (71.6%) of the CFIs and 34 (42.0%) of the MCA-PSV MoM measurements were abnormal. The result of one of these tests was abnormal in 65 evaluations (80.3%) and the results of both tests were abnormal in 27 evaluations (33.3%). All fetuses diagnosed as being severely anemic by at least one of the hemoglobin criteria during cordocentesis had an abnormal result by at least one of the noninvasive tests. Before the second and third transfusions, the combined use of the CFI and MCA-PSV MoM predicted severe fetal anemia with 100% sensitivity. When the CFI and MCA-PSV MoM measurements were normal, the negative likelihood ratio was zero.

CONCLUSION

When associated, CFI and MCA-PSV MoM were accurate predictors of severe fetal anemia.