Aim: The relationship between the changes in fibroid blood flow and fibroid diameter during the administration of GnRH agonists and antagonists was examined using superb microvascular imaging (SMI).
Methods: Changes in the maximum fibroid blood flow and diameter at weeks 0, 2, 4, and 8 were compared between the relugolix, a GnRH antagonist, and leuprolide, a GnRH agonist, groups.
Results: Data were collected for 16 fibroids from 12 patients in the relugolix group and 12 fibroids from 9 patients in the leuprorelin group. A significant decrease was observed in the fibroid diameter at 8 weeks in the relugolix group, but no significant change was observed at any time point in the leuprorelin group. In the relugolix group, a significant correlation were observed between changes in blood flow at 2 weeks and fibroid diameter changes at 2 and 4 weeks, and between changes in blood flow at 4 weeks and fibroid diameter changes at 4 weeks. No significant correlation was observed in the leuprorelin group.
Conclusion: In the treatment of uterine fibroids with relugolix, a reduction in fibroid blood flow assessed by SMI may suggest a subsequent reduction in fibroid size. These results provide useful insights when making the decision whether or not to continue relugolix administration.
Keywords: fibroid blood flow; leuprorelin (leuprolide); relugolix; superb microvascular imaging; uterine fibroids.
© 2025 The Author(s). Journal of Obstetrics and Gynaecology Research published by John Wiley & Sons Australia, Ltd on behalf of Japan Society of Obstetrics and Gynecology.