Quality assurance and its impact on ovarian visualization rates in the multicenter United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS).

OBJECTIVE

To describe the quality assurance (QA) processes and their impact on visualization of postmenopausal ovaries in the ultrasound arm of a multicenter screening trial for ovarian cancer.

METHODS

In the United Kingdom Collaborative Trial of Ovarian Cancer Screening, 50 639 women aged 50-74 years were randomized to the ultrasound arm and underwent annual transvaginal ultrasound (TVS) examinations. QA processes were developed during the course of the trial and included regular monitoring of the visualization rate (VR) of the right ovary. Non-subjective factors identified previously as impacting on VR of the right ovary were included in a generalized estimating equation model for binary outcomes to enable comparison of observed vs adjusted VR between individual sonographers who had undertaken > 1000 scans during the trial and comparison between centers. Observed and adjusted VRs of sonographers and centers were ranked according to the highest VR. Analysis of annual VRs of sonographers and those of the included centers was undertaken.

RESULTS

Between June 2001 and December 2010, 48 230 of 50 639 women attended one of 13 centers for a total of 270 035 annual TVS scans. One or both ovaries were seen in 228 145 (84.5%) TVS scans. The right ovary was seen on 196 426 (72.7%) of the scans. For the 78 sonographers included in the model, the median difference between observed and adjusted VR was -0.7% (range, -7.9 to 5.9%) and the median change in VR rank after adjustment was 3 (range, 0-18). For the 13 centers, the median difference between observed and adjusted VR was -0.5% (range, -2.2 to 1%), with no change in ranking after adjustment. The median adjusted VR was 73% (interquartile range (IQR), 65-82%) for sonographers and 74.7% (IQR, 67.1-79.0%) for centers. Despite the increasing age of the women being scanned, there was a steady decrease in the number of sonographers with VR < 60% (21.4% in 2002 vs 2.0% in 2010) and an increase in sonographers with VR > 80% (14.3% in 2002 vs 40.8% in 2010). The median VR of the centers increased from 65.5% (range, 55.7-81.0%) in 2001 to 80.3% (range, 74.5-90.9%) in 2010.

CONCLUSIONS

A robust QA program can improve visualization of postmenopausal ovaries and is an essential component of ultrasound-based ovarian cancer screening trials. While VR should be adjusted for non-subjective factors that impact on ovarian visualization, subjective factors are likely to be the largest contributors to differences in VR.