Fetal transient occipital bone protuberance during early pregnancy

Objective: To describe the prenatal sonographic findings and pregnancy outcome of fetuses with transient occipital bone protuberance (TOBP). Methods: Five fetuses with TOBP were identified at routine 14 to 15 weeks ultrasound. The sonographic examination was repeated during pregnancy and the neonates were examined after birth. Results: The occipital bone protuberance disappeared by 24 weeks in all five cases, and the postnatal examination of the skull was normal. Conclusions: Isolated TOBP is rare during early pregnancy. Ultrasound follow-up is suggested and disappearance of the lesion can be expected in most, if not all the cases with normal skull at birth.