Fatal neonatal stroke from a prenatal cardiac thrombus.

Despite careful investigation, the etiology of many perinatal arterial strokes is unknown. We report on a 5-day-old boy with a cardiac thrombus of prenatal origin resulting in a fatal postnatal stroke. The thrombus was discovered only at autopsy, challenging the assumption of a placental source of embolus in perinatal strokes in the absence of macroscopic and microscopic examination of the heart.