Caput succedaneum mimicking a cephalocele.

Caput succedaneum is relatively common at birth but infrequently diagnosed in utero. It has a benign prognosis, but it is very important not to misdiagnose it as a cephalocele, which carries a guarded prognosis. We present the case of a patient who experienced preterm labor and premature rupture of the membranes at 28 weeks' menstrual age. Our initial diagnosis was cephalocele, but after the male infant was delivered by cesarean section, examination revealed no bone defect, and our final diagnosis was caput succedaneum. We also discuss the sonographic findings and diagnostic differences between caput succedaneum, cephalocele, and other fetal head masses.