Research question: Available evidence showed that the presence of ovarian endometriomas do not interfere with ovarian response to hyper-stimulation. However, the mean size of the endometriomas included in these studies is generally small and two recent investigations suggested that follicular development could be conversely impaired when focusing on larger endometriomas. However, these studies could not disentangle a clear threshold above which endometriomas could become detrimental.Design: To identify this threshold, we retrospectively selected women without a history of surgery for ovarian cysts and who underwent IVF in the presence of unilateral endometriomas with a mean diameter between 20 to 49 mm. Selected women were divided into three endometrioma size categories: 20-29 mm (Group 1, n=23), 30-39 mm (Group 2, n=23) and 40-49 mm (Group 3, n=21).Recruitment for each category was censored at about 21 women to ensure equal statistical power for every group.
Results:The response to hyper-stimulation was equal or superior in the affected gonads in 8 women (35%, 95%CI: 16-57%), 7 women (30%, 95%CI: 13-53%) and 2 women (10%, 95%CI: 2-30%) in group 1, 2 and 3, respectively. The median [interquartile range] number of developed follicles in the affected and intact ovaries was 6 [3-7] and 5 [4][5][6][7][8][9] in group 1 (p=0.21), 4 [1-6] and 4 [3][4][5][6][7] in group 2 (p=0.08), 5 [3-7] and 7 [4][5][6][7][8] in group 3 (p=0.01), respectively.
Conclusion:The threshold to be used to distinguish between endometriomas that could and could not interfere with ovarian response is 4 cm in diameter.