[Role of middle cerebral artery Doppler in the management of Rhesus alloimmunization cases].

Background: The most common cause of anemia remains fetal red cell alloimmunization. Although after the systematization of prophylactic anti-D gamma globulin decreased the number of cases, has not eliminated the problem.

Objectives: To evaluate the role of the fetal middle cerebral artery peak systolic velocity in the management of fetus at risk for anemia due to Rh alloimmunization and analyze the effect in perinatal outcomes.

Material And Method: 68 pregnancies complicated by Rh alloimmunization, in La Paz Hospital (Madrid, Spain) since February 2006 until August 2009, with maternal antibody titers > or = 1:32, affected in previous pregnancies and/or anti-Kell isoimmunization. In every case it was measured the middle cerebral artery peak systolic velocity and the fetal hemoglobin concentration in blood obtained either by cordocentesis or at delivery.

Results: For the detection of moderate-severe fetal anemia, Doppler ultrasonography of the middle cerebral artery had a sensitivity of 80% (95% confidence interval: 59.8 to 100%), a specificity and positive predictive value of 100%, and a negative predictive value of 85.7% (95% confidence interval: 70.7 to 100%). The Pearson correlation coefficient between estimated hemoglobin and real hemoglobin was 0.71. The 22% (15/68) of the fetuses required at least one intrauterine transfusion making a total of 26. In 23% (6/26) of them appeared complications. The last middle cerebral artery peak systolic velocity measurement is associated with neonatal anemia and/or icterus (p < 0.01), anemia during the hospitalization (p < 0.05) and neonatal transfusion (p < 0.05).

Conclusion: The measurement of the middle cerebral artery peak systolic velocity predicts moderate-severe fetal anemia cases, which are the most important in the clinical management because of the need of active treatment with intrauterine transfusion or induction labor.