Is Dienogest More Effective Than Ethinylestradiol/Dienogest or Desogestrel in Reducing Ovarian Endometrioma Size? A Sonographic Retrospective Cohort Study

Objective: To compare the long-term sonographic effectiveness of Dienogest (DNG)2mg, Ethinylestradiol/Dienogest (EE/DNG), and Desogestrel (DSG) 75 µg in reducing ovarian endometrioma (OMA) volume, and to evaluate their performance relative to untreated patients under active follow-up (A-FU).Methods: This retrospective monocentric cohort study included women aged 16-55 years with transvaginal ultrasound (TV-US)-confirmed typical OMAs.Patients received DNG, EE/DNG, DSG, or no therapy (A-FU).OMAs' volume was calculated using the prolate ellipsoid formula at baseline and at 12 and 24 months; 36-month data were included when available.Longitudinal changes in volume were analysed using a linear mixed-effects model (LMM) with random intercepts.A secondary analysis employed log-transformed volumes to account for baseline heterogeneity.Results: Sixty-three patients completed at least 12 months of followup (DNG n=14; EE/DNG n=39; DSG n=28; A-FU n=10).At baseline, significant differences in age and cyst size were observed, with the DNG group presenting the largest volumes (87,488 ± 68,211 mm 3 ).All hormonal therapies induced progressive volume reduction, while untreated OMAs tended to increase.The LMM revealed a significant time × treatment interaction for DNG at 24 months (p = 0.020*), indicating a reduction exceeding the natural trajectory despite larger initial cysts.DSG and EE/DNG showed similar downward trends but without statistical significance in absolute-volume models.In contrast, the log-transformed analysis showed that all three hormonal treatments exhibited regression, whereas the A-FU group did not.Conclusions: Hormonal therapy effectively reduces OMA volume, with DNG showing the strongest and statistically significant effect.When adjusted for baseline heterogeneity, DSG and EE/DNG demonstrate comparable relative efficacy.Active hormonal therapy should be preferred over observation, while treatment choice should remain individualized.Prospective multicenter studies are needed to confirm these findings.