Perinatal outcomes and survival predictors of severe red-cell alloimmunization treated by intrauterine transfusion

To evaluate perinatal survival rates and predictors in severely anemic fetuses that underwent intrauterine transfusion (IUT).

This was a retrospective study of both Turkish and Syrian patients who underwent IUT for fetal anemia due to Rh alloimmunization between 2015 and 2019. The association between pretransfusion factors and perinatal survival was evaluated by multivariate logistic regression. Receiver operating characteristics (ROC) curves were used to identify the level of fetal hemoglobin deficits that predict perinatal survival.

Eighty-seven IUTs were performed in 42 pregnancies. Approximately 75% of fetuses were severely anemic and the overall perinatal survival rate was 50%. The survival rate was better in Syrian refugees compared to Turkish patients (71.4% vs. 39.3%, p < 0.05). In univariate analysis, hydrops presence (odds ratio [OR] = 0.2; 95% confidence interval [CI] = 0.05-0.7; p < 0.05), first IUT week (OR = 1.4; 95% CI = 1.1-1.8; p < 0.05), pretransfusion hemoglobin level (OR = 1.99; 95% CI = 1.22-3.27; p < 0.05), hemoglobin deficit (OR = 0.5; 95% CI = 0.3-0.8; p < 0.05), and birth week (OR = 2.3; 95% CI = 1.3-3.9; p < 0.05) were associated with survival. However in a multivariate analysis, only hemoglobin deficit (OR = 0.47; 95% CI = 0.22-0.99; p < 0.05) and birth week (OR = 3.3; 95% CI = 1.1-10.3; p < 0.05) were found to be associated with survival. On ROC analysis, a hemoglobin deficit of ≤6.25 g/dl showed a sensitivity of 0.95 and specificity of 0.62 for predicting perinatal survival.

Despite the improvement in the treatment of fetal anemia, perinatal survival rate remains extremely low in severely anemic cases. Among pretransfusion factors, hemoglobin deficit seemed to be most important in predicting survival during fetal anemia.