To assess the long-term outcome of performing uterine artery embolization (UAE) using small particles in women with symptomatic adenomyosis (AD).

Twenty-seven consecutive women (median age 42 years, range 29–53 years) with AD, in eight cases AD combined with fibroids, who underwent UAE between February 2015 and January 2019, were retrospectively analyzed. The embolization was performed using small-sized polyvinyl alcohol particles (100 μm and 300 μm). The patients completed the Uterine Fibroid Symptom and Quality of Life questionnaire at baseline and at a 42-month follow-up (range 24–71). The junction zone (JZ) thickness and uterine volume were also calculated at baseline and at a three-month follow-up.

The total symptom severity score (SSS) decreased from a median of 59 (range 34–78) at baseline to a median of 9 (range 3–47) at the end of this study; the health-related quality of life score (HRQOL) increased from a median of 38 (range 23–49) at baseline to a median of 84 (range 46–97) at 42 months. Twenty of the 27 patients were asymptomatic. The clinical response of the remaining seven women was little improvement in their symptoms, and one of the seven women underwent a hysterectomy at 35 months. Twenty-six of the 27 (96%) patients had a preserved uterus at the 42-month follow-up. There was no difference after UAE in SSS, HRQOL, junction zone (JZ) thickness, and uterus volume between patients with pure AD and those with AD combined with fibroids (p = 0.729, 0.710, 0.973, and > 0.99). There was no difference in the JZ thickness and uterus volume at baseline between the asymptomatic women and the women with an insufficient response (p = 0.854 and 0.253), and there were no major complications afterwards.

From the long-term follow-ups, it could be seen that UAE using small particles is safe and effective in treating AD, especially in preserving the uterus. There is no relationship between the clinical outcomes and the initial presence of AD, with or without fibroids, and the JZ thickness at baseline does not seem to be a predictor for the long-term outcome of UAE.