From size to shape: morphological ultrasound remodelling of large ovarian endometriomas under dienogest therapy.

RESEARCH QUESTION: What is the long-term efficacy of dienogest in treating large ovarian endometriomas (≥5 cm), assessed by transvaginal sonography (TVS) changes in size, greyscale, colour Doppler features, #Enzian score and symptoms over time? DESIGN: This retrospective observational study included 51 participants with a TVS-diagnosed ovarian endometrioma of ≥5 cm, treated with dienogest 2 mg daily. TVS was performed at 6, 12 and 24 months (24-month data being available for 35 patients), using International Ovarian Tumor Analysis terminology and #Enzian score. Pain was assessed by a visual analogue scale, and menstrual blood loss by self-perception. RESULTS: In total 54 endometriomas were analysed. The mean maximum diameter decreased from 60.0 mm (95% CI 55.9-64.1 mm) at baseline to 38.9 mm (95% CI, 34.8-43.0 mm) at 6 months (P < 0.001), and the reduction was sustained at 24 months (P < 0.001). The mean volume decreased from 70.8 ml (95% CI 61.1-80.6 ml) at baseline to 27.7 ml (95% CI 17.9-37.4 ml) at 6 months (P < 0.001), with the reduction persisting at 24 months (P < 0.001). The frequency of ground-glass content decreased from 90.7% (49/54) to 66.7% (36/54) at 6 months (P < 0.001). Wall collapse was observed in 2/54 (3.7%) cases at baseline and 8/54 (14.8%) at 12 months (6 versus 12 months, P = 0.028). The frequency of a colour Doppler score of 1 increased from 48.1% (26/54) at baseline to 66.7% (36/54) at 6 months, (P < 0.001). The proportion of patients with #Enzian #O1 endometriomas was 40.7% (22/54) at 12 months, compared with no cases at baseline (P < 0.001). Severe dysmenorrhoea and heavy menstrual bleeding frequency improved by 6 months. CONCLUSIONS: Dienogest is effective in reducing the volume of large ovarian endometriomas and downstaging the #Enzian score. Recognizing therapy-related TVS changes may avoid misinterpretation as atypical lesions and guide follow-up.