OP11.04: Continuing education on NT: an exercise on caliper placement for NT measurement

Objectives: During the first trimester screening, NT measurement is one of the main components in calculating the risk for trisomies. Systematic error is common among accredited sonographers in audit trail. According to the Fetal Medicine Foundation criteria for NT measurement, the calipers should be placed at the thickest area of the subcutaneous translucency with the calipers’ arm flush with the line. The objective of this study is to observe the effectiveness of an alignment exercise in improving the accuracy of individual sonographers in caliper placement. Methods: Twenty mid sagittal pictures suitable for NT measurement were selected. Each picture is duplicated into a set of 4 pictures with different caliper placements. (A total of 20 sets= 80 pictures). Fifteen FMF accredited sonographers from two of the teaching hospitals in Singapore took part in the exercise. Twenty MCQ questions were created with these 20 sets of pictures. One out of each set of 4 pictures has the ideal caliper placement. The results were assessed anonymously using an electronic voting system. The aggregate scores were disclosed after each question. The same procedure was repeated again after a 20 minute short revision lecture on criteria of NT measurement by a FMF accredited trainer. The results were saved and statistically analysed for the individual and group accuracy of measurement before and after the lecture. Results: The results are shown in Table 1. Conclusions: There is a statistically significant improvement in caliper placement for FMF accredited sonographers after a caliper placement exercise and lecture. The improvement happened for the sonographers in both the hospital. Continuing education and refresher courses for caliper placement should be conducted from time to time to standardize the caliper placement for FMF accredited sonographers.