Purpose: to verify if there is an association between the mean blood velocity in the descending thoracic aorta and fetal anemia diagnosis. Methods: this is a prospective, cross-sectional study in which the mean blood velocities in the fetal aorta, in 66 fetuses at risk for severe anemia due to severe Rh immunization, and cord blood hemoglobin levels were analyzed comparatively. The hemoglobin level was obtained by cordocentesis if an intravascular transfusion was performed for severe anemia, however, if the fetus received an intrauterine transfusion by the intraperitoneal route or if the fetus did not receive a transfusion at all, hemoglobin level was measured at the time of pregnancy termination by umbilical cord puncture. The authors made a statistical association between the mean blood velocity in fetal descending thoracic aorta and the diagnosis of fetal anemia. The c² test was used for statistical analysis and a p value <0,05 was used to indicate significance. Results: there was a significant and indirect association between the mean blood velocity in the descending thoracic aorta and the detection of fetal anemia. The mean blood velocity in fetal thoracic aorta had a sensitivity of 47.4% for the diagnosis of moderate fetal anemia (Hg<10.0 g/dL), with a p value <0.01 by the Fisher exact test, and a sensitivity of 54.5% for severe Rh isoimmunization (Hg<7.0 g/dL), with a p value =0.01. Conclusion: this study revealed a significant indirect correlation between mean blood velocity in the descending thoracic aorta and the detection of fetal anemia due to Rh isoimmunization.
Isoimmunization; Doppler flowmetry; Cordocentesis; Fetal anemia
