Oocyte quality in women with endometriosis-associated infertility

©Lemau Studio - shutterstock.com

Endometriosis negatively impacts the quality of oocyte and ovarian reserve, according to a prospective study in the journal Gynecological Endocrinology. The Russian investigators also found that endometriosis had a harmful and sustained effect on ovarian reserve following ovarian cystectomy.

Methods
The study included 130 infertile reproductive-aged women ages 29 to 40 who underwent in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) at the Peoples’ Friendship University of Russia in Moscow in 2018 and 2019.  Patients were divided into three groups: surgical treatment for recurrent unilateral endometriomas (n = 50), surgical treatment for nonrecurrent unilateral endometriomas (n = 50) and a control group with tubal factor infertility (n = 30).

Results
In the two treated groups, the number of antral follicles and the number of oocytes obtained via transvaginal puncture of the follicles were significantly fewer in comparison with the control group. For example, the number of antral follicles in the affected ovary in the recurrent unilateral endometriomas group was on average 4.1; in the nonrecurrent unilateral endometriomas group, 5.4; and for the control group at both sides, 12.5. Similarly, the number of antral follicles in the intact ovary before IVF via ultrasound was 7.2 and 7.8, respectively, for the two treated groups.

The total number of oocytes recovered in the recurrent unilateral endometriomas group and the nonrecurrent unilateral endometriomas group, were 8.8 and 9.2, respectively, compared to 10.1 in the control group.

Similarly, the number of high-quality oocytes obtained in the metaphase II (MII) stage for recurrent unilateral endometriomas, nonrecurrent unilateral endometriomas and control were 4.1, 5.2 and 9.6 (control), respectively. 

The authors noted that absence of a statistically significant difference (P= 0.005) in the number of obtained oocytes for the two treated groups “is associated with the unilateral location of the endometrioma, as well as the compensatory capabilities of the intact ovary.”

They also observed that the number of oocytes obtained from an ovary containing an endometrial cyst was dramatically lower than for the contralateral ovary without any detected cysts, especially when the endometrioma diameter was greater than 3 cm.Conclusions
Study results demonstrate a statistically significant increase in the number of immature oocytes in the metaphase I (MI) stage and in the number of immature oocytes at the germinal vesicle (GV) stage in the two groups of patients with endometriosis-associated infertility, compared to the control group. There was also deterioration in the quality of oocytes obtained from patients with endometriomas > 3 cm.

Prior to surgery, endometriomas ≤ 10 mm were found in 36% of the women with recurrent unilateral endometriomas versus 48% in the group with nonrecurrent unilateral endometriomas. Other percentages for sizes were 40% and 36% (between 10 mm and 20 mm), 16% and 12% (between 20 mm and 30 mm), and 8% and 2%, (between 30 mm and 40 mm), respectively. 

Every fourth oocyte extracted from the ovary containing an endometrial cyst had structural changes. In some patients, this change reflected a displacement of the nucleus in the oocyte membrane, or a partial or complete absence of the nuclear envelop. Various signs of degenerative changes were also observed. “According to literature, morphology itself could be influenced by other factors, such as the ovarian stimulation or the hormonal milieu; therefore, its potential as predictive factor of clinical outcome needs further investigation,” wrote the authors.

Testing the ability of immature oocytes to undergo oocyte in vitro maturation (IVM) to the MII stage showed that a significantly lower number of GVs and MI occytes were able to attain the MII stage in the two endometriosis groups as opposed to controls.