Transvaginal sonographic follow-up on the formation of fetal cephalocele at 13-19 weeks' gestation.

An occipital meningocele was detected by transvaginal sonography in a fetus of 13 weeks' gestation. This changed at 14 weeks to a cephalocele, which disappeared at 15-16 weeks and was detected again at 19 weeks. It is possible that sliding backward and forward of the herniated brain tissue caused this sequence of events.