[Absent intracranial translucency--new ultrasound marker for spina bifida at 11-13+6 weeks of gestation].

Spina bifida is the most common abnormality of the fetal central nervous system. Prenatal diagnosis is usually made by ultrasound in the second or third trimester of pregnancy. However, first trimester detection of spina bifida is still a challenge. A new indirect ultrasound sign of open spina bifida between 11-13 6 weeks of gestation (w.g.) has been recently described. The marker is associated with an absence of intracranial translucency (IT) in the mid-sagittal plane. We present a case report of an open spina bifida detected at 13+2 weeks of gestation with an absent IT. The main ultrasound characteristics of normal and absent IT are described. In addition, the diagnostic role of three-dimensional (3D) transvaginal ultrasound is also discussed.