Poor response of ovaries with endometrioma previously treated with cystectomy to controlled ovarian hyperstimulation

Purpose: To compare ovarian response to controlled ovarian hyperstimulation (COH) between normal ovaries and ovaries previously treated surgically for unilateral ovarian endometrioma. Methods: From January 1996 to December 2001, 32 patients with unilateral ovarian endometrioma previously treated surgically underwent 38 cycles of COH. Their records were reviewed retrospectively. The number of dominant follicles observed on the day of hCG injection and the number of eggs retrieved from the diseased and the normal ovaries in each patient were compared. Results: The numbers of dominant follicles from diseased and normal ovaries were 1.9 +/- 1.5 and 3.3 +/- 2.1, respectively (P < 0.001). During ovum pick up, the numbers of eggs retrieved from diseased and normal ovaries were 2.9 +/- 2.6 and 6.1 +/- 4.1, respectively (P < 0.0001). For diseased ovaries, 21.1% (8/38) had no dominant follicles, while only 7.9% (3/38) of normal ovaries lacked dominant follicles. The clinical pregnancy rate and the implantation rate per embryo transfer were 33.3 and 17.6%. Conclusions: Surgery for ovarian endometrioma may damage ovarian reserve. It potentially results in poor ovarian response to COH, compared to the response of the contralateral normal ovary in the same individual.