The anatomy of nuchal translucency at 10-14 weeks gestation in fetuses with trisomy 21: An incredible medical mystery.

Nuchal translucency (NT) is a hypo-echoic region of subcutaneous fluid accumulation in the posterior neck at the level of the cervical spine between the skin and soft tissues found at 10-14 weeks gestation. This ultrasound finding is important because increased NT measurements place the fetus at increased risk for chromosomal and structural abnormalities. It is a fascinating phenomenon that displays the intersection of anatomy, development, and imaging. In addition, with the ever increasing use of ultrasound in anatomy, NT is a readily demonstrable example of how important ultrasound has become to the practice of medicine. Articles on NT were obtained from OVID database and reviewed for their contribution to an understanding of the anatomical basis of NT. Whereas it is well established that the ultrasound finding of increased NT is a sensitive marker for Trisomy 21 at 10-14 weeks gestation, why this phenomena occurs has yet to be explained. The basis of nuchal edema is most likely multifactorial, a combination of delayed or disturbed lymphangiogenesis, cardiac and vascular abnormalities, and abnormal extracellular matrix components. Further research on the development of the fetal head and neck related to lymphatic development and fluid regulation during 8-14 weeks gestation will enable a greater understanding of how and why increased NT occurs compared to what is currently known. This could lead to early intervention to manage some of the repercussions of Trisomy 21 and other abnormalities related to NT.