Factors influencing visualization of the intracranial translucency during first-trimester screening for aneuploidy

American Journal of Perinatology, 04/26/2012

The IT can be visualized in the majority of patients in the standard midsagittal plane used for measurement of the nuchal translucency. Visualization is significantly associated with crown–rump length, gestational age, maternal weight, and fetal position. Visualization of the IT is feasible.


  • Ultrasound images for patients undergoing first–trimester screening for aneuploidy from January 1, 2009, through July 31, 2009, were reviewed for IT visualization, defined as an intracranial translucency parallel to the nuchal translucency.
  • Second–trimester ultrasounds and delivery records were reviewed for the presence of fetal ONTD.


  • The IT was visualized in 74.8% of 759 gestations studied at a mean gestational age of 12 weeks, 5 days.
  • Among gestations where the IT was visualized, we found a larger crown–rump length, lower maternal weight, and more fetuses in the supine position (p < 0.0001).
  • Predictive models for visualization of the IT were formulated based on these factors.

Print Article Summary Cat 2 CME Report