+61 3 9412 2975 nuchaltrans@ranzcog.edu.au

Image Assessment

Logbook / Audit Images Scoring Method

  1. Three images (3) are to be submitted for Logbooks and and 1 NT image (+1 marker if certified) for Audits.
  2. Each image will be assessed individually on the following six criteria –
  • Image size (head & thorax)
  • Mid Sagittal section
  • Caliper placement
  • Maximum lucency
  • Neutral Head position
  • Representative length of nuchal membrane


  • To pass an image 4 of the assessment criteria must be met. However, if the same assessment criteria is not met in any of the three images, a further three images will be requested by the assessor. In this situation the logbook will not pass overall, even though a score of 4 has been obtained for each image. for e.g. If all three images fail on the criteria of caliper placement, the logbook will not pass and another logbook of three images will be requested.
  • All images must be passed.
Six criteria     Image 1   Image 2    Image 3
Image size (head & thorax)   X X
Mid Sagittal section


 Caliper placement   X
 Maximum lucency  
 Neutral Head position  
 Representative length of nuchal membrane  

 This logbook submission did not pass, image 3 scored × for 3 of the criteria.