Limitations of amniography in the prenatal diagnosis of spina bifida.

A fetus with an open, noncystic myelomeningocele was detected at the 22nd week of gestation in a woman monitored for advanced maternal age. The lesion could not be demonstrated on amniography. In 13% of published reports amniography failed to detect significant spina bifida lesions. This false-negative rate seems related to the noncystic nature of some neural tube defects at midgestation.