A fetal subdural hematoma (SDH) was diagnosed in a patient with sickle cell disease (SCD) during a routine ultrasound exam in the 30th week of pregnancy. A scan performed a few days earlier had revealed no abnormalities. After interdisciplinary consultation with neurosurgeons and neonatologists, a cesarean section was performed since acute subdural bleeding was hypothesized and the mother's condition was critical. After surgery, the diagnostic procedures revealed that the child and the mother had also suffered from thrombocytopathy, which probably jointly contributed to causing the bleeding; in general, anemia and hypoxia may also play an important role. The newborn had a good neurological outcome. Ultrasound features do not reflect the underlying cause and therefore predicting the prognosis is challenging. In most cases, prenatal counseling is difficult because of the unknown underlying cause and because there are no ultrasound or magnetic resonance imaging criteria to define which cases can benefit from delivery or expectant management. Where there is acute bleeding, the child could benefit from delivery and surgical evacuation of the hematoma. Further investigation to identify the cause of the bleeding can improve management and prognosis.