Intraobserver and interobserver variability of ovarian volume, gray-scale and color flow indices obtained using transvaginal three-dimensional power Doppler ultrasonography.

OBJECTIVE

To assess intraobserver and interobserver variability in ovarian volume and gray-scale and color flow index measurements using transvaginal, three-dimensional, power Doppler ultrasonography.

METHODS

Eleven women (22 ovaries) were examined on day 8 of controlled ovarian hyperstimulation therapy, which was part of their in vitro fertilization treatment protocol. The patients were examined twice by the first observer and once by the second observer. The acquired volume datasets were analyzed using the VOCAL imaging program, enabling the assessment of ovarian volume, vascularization index (VI), flow index (FI), vascularization flow index (VFI) and mean grayness (MG). For these parameters the intraclass (intra-CC) and interclass (inter-CC) correlation coefficients, within-observer and between-observers repeatability coefficient (r) and limits of agreement were calculated.

RESULTS

Both intraobserver and interobserver repeatability of ovarian volume measurements were considered very good with an intra-CC value of 1.00 and inter-CC value of 0.99, respectively. Also VI, FI, VFI and MG measurements were repeatable by a single observer, the intra-CC ranging from 0.82 to 0.91. The interobserver reproducibility was also good for VI, VFI and MG measurements (inter-CC values 0.73, 0.70 and 0.81, respectively), but for FI measurements the reproducibility was poor (inter-CC = 0.29, r = 7.87).

CONCLUSIONS

In general, the intraobserver reproducibility was better than interobserver reproducibility for all parameters. The volume assessments were reproducible both by one observer and by two separate observers. The intraobserver and interobserver variabilities were acceptable for VI, VFI and MG, whereas for FI the interobserver reproducibility was poor. Our results suggest that measurement of gray-scale and color Doppler flow indices is reproducible thus allowing them to be used in clinical practice and research.