differential prenatal diagnosis of cystic hygromata and encephalocele by ultrasound examination

The difficulty in distinguishing an encephalocele from a cystic hygroma has recently been highlighted by five patients referred to our unit with an incorrect diagnosis of cystic hygroma. A review of the literature revealed four other cases of misdiagnosis. Based on review of 46 patients with one or other diagnosis, we have attempted to establish guidelines to aid diagnosis. We have always been able to identify the bony defect in the fetal vault in cases of encephaloceles. The pattern of the septa is usually characteristic in cystic hygroma.