It was also associated with a subsequent increased rate of spontaneous pregnancy women who had documented prior sub-fertility (OR 5.21 CI 2.04-13.29). AUTHORS' CONCLUSIONS: There is some evidence that excisional surgery for endometriomata provides for a more favourable outcome than drainage and ablation, with regard to the recurrence of the endometrioma, recurrence of symptoms and subsequent spontaneous pregnancy in women who were previously subfertile.