Purpose or Case Report: Fetal anemia is a severe condition with diverse etiologies that can lead to complications, including fetal hypoxia, heart failure, hydrops fetalis and intrauterine fetal death if left untreated. In severe cases, intrauterine transfusion (IUT) is a life-saving intervention. The impact of fetal anemia on brain development remains unclear. This study aimed to evaluate neuroimaging findings in fetuses diagnosed with anemia using magnetic resonance imaging (MRI).
Methods & Materials: We performed a retrospective cohort study including all fetuses diagnosed with fetal anemia on fetal blood sampling in a single tertiary center between October 2010 and October 2024. Pregnancies were included if they underwent fetal brain MRI following anemia diagnosis. Data collected included maternal and fetal characteristics, IUT details, and prenatal MRI findings.
Results: 55 pregnancies met inclusion criteria with 27 monochorionic twin and 28 singleton pregnancies for a total of 82 fetuses. Among 61 surviving fetuses (21 demised), the mean gestational age at MRI was 27.7 weeks and the average pre-transfusion hemoglobin level was 4.6 g/dL. Eleven cases met criteria for severe anemia (Hb <3.0 g/dL). MRI revealed at least one brain abnormality in 65.5% of cases. MRI findings included: 1. Hemorrhagic lesions (n=16, 26.2%), ranging from germinal matrix to parenchymal hemorrhages, with intraventricular hemorrhage in 18% of cases. 2. Restricted diffusion (n=11, 18.0%), consistent with ischemic changes of the brain parenchyma, with 90.9% being multifocal. 3. Corpus callosum anomalies (n=6, 9.8%), characterized by thinning and foreshortening. 4. Ventriculomegaly (n=3, 4.9%), with one case secondary to obstructive hydrocephalus. 5. Cerebral edema (n=2, 3.3%). 6. Encephalomalacia (n=2, 3.3%), indicative of prior injury.
Conclusions: CNS abnormalities are common in fetuses with anemia, with 65.5% showing at least one brain abnormality. The most common CNS findings include hemorrhagic and ischemic lesions. Our findings emphasize the importance of fetal MRI in the management of fetal anemia to guide clinical decisions and monitor brain injury following intrauterine transfusion.