Patients with pericardial teratomas usually present shortly after birth with cardiorespiratory distress or in utero with hydrops fetalis. We report a case in which the tumor was diagnosed in utero using sonography during a routine obstetric examination. Sonograms showed a 3‐cm echogenic mass compressing the right atrium. The lesion was inhomogeneous with solid and cystic areas. The fetus was followed to term, and additional radiologic studies were performed before the infant underwent surgery. Prenatal identification of a pericardial teratoma is essential for planning fetal management and delivery and potential prenatal surgery. © 2000 John Wiley & Sons, Inc. J Clin Ultrasound 28:194–198, 2000.

Patients with pericardial teratomas usually present shortly after birth with cardiorespiratory distress or in utero with hydrops fetalis. We report a case in which the tumor was diagnosed in utero using sonography during a routine obstetric examination. Sonograms showed a 3-cm echogenic mass compressing the right atrium. The lesion was inhomogeneous with solid and cystic areas. The fetus was followed to term, and additional radiologic studies were performed before the infant underwent surgery. Prenatal identification of a pericardial teratoma is essential for planning fetal management and delivery and potential prenatal surgery.