Effect of ovarian surgery on ovarian reserve and fertility

Abstract

The objective of this thesis was to investigate short- and long-term effects of ovarian surgery on the ovarian reserve of women of reproductive age. This research also considered their reproductive outcomes with regard to conceiving spontaneously or using assisted reproductive techniques (ART). We also wished to explore how women perceived the information they received about fertility when planning for ovarian surgery.

In paper I, a cross-sectional study that included 106 women, we investigated patients’ perceptions of the fertility-related information they received as well as fertility distress prior to ovarian cyst surgery. Although a high proportion of the women (72 %) desired to have children in the future, only half recalled receiving information about the potential impact of surgery on fertility. In a multivariable logistic regression, desire for children was the only association with recalled fertility-related information. Additionally, more than half of the women (54 %) reported fertility distress with VAS-scores ≥ 5 prior to surgery.

Paper II involves a prospective clinical cohort study that included 75 women planned for conservative ovarian cyst surgery (cystectomy, ovarian resection or unilateral oophorectomy). We investigated the effects of removed cysts’ histopathology on women’s ovarian reserve, estimated as serum concentrations of Anti-Mullerian Hormone, AMH. The AMH levels declined significantly from presurgery levels of 2.7 μg/L (0.2-16.9) to 1.6 μg/L (0.2-9.9) at three months, and the levels remained low at six months, 1.6 μg/L (0.2-8.3) (p<0.001, respectively). In patients who had a single cyst enucleation, a reduction was observed after surgery for both endometriomas and dermoid cysts. In a logistic regression, the only predictive factor found for the decline of AMH serum concentrations was a higher baseline AMH level prior to surgery.

In paper III, we prospectively investigated the changes in AMH after a long-term postoperative follow-up of two years in 66 of the women included in the clinical cohort study. The progressive post-operative decline of serum AMH concentrations continued over time. The AMH serum concentration significantly reduced from 2.7 μg/L at baseline to 2.0 μg/L at six months. We observed a further reduction to 1.0 μg/L at the two-year follow-up (p = 0.001, respectively). Nonetheless, women who attempted pregnancy succeeded in 58 % of the cases. Women with normal or high AMH at baseline had a higher chance of conceiving, regardless of their AMH reduction over time.

In paper IV, we examined the clinical pregnancy rate after Assisted Reproductive Technology (ART) in a cohort of 76 women with a history of unilateral oophorectomy (UO), as compared to 12879 controls. Exposed women with UO and unexposed controls were included at three ART Swedish clinics. In this multicentre study, single embryo transfer was performed in 77 % of cases; analysis showed a significant reduction of 30 % in the clinical pregnancy rate of women with UO compared to controls, both crude and after adjustment for age.

Conclusion: The studies included in this thesis indicate that the ovarian reserve, estimated by its biochemical marker AMH, decreases significantly after conservative ovarian surgery for cysts in women of fertile age. The post-operative AMH decrease continues two years following the ovarian surgery, even though no macroscopic ovarian tissue was reported as being removed at the time of surgery. The reduction in AMH does not seem to affect fertility in women presenting with normal or high AMH serum concentrations prior to ovarian surgery. On the other hand, women of fertile age who had a previous surgical removal of one ovary had reduced chances of pregnancy, estimated as reduced clinical pregnancy rate after ART. Women require this important information in order to make decisions regarding their reproductive ability; however, our research evidenced that women were not properly informed of the potentially negative effects of ovarian surgery on reproduction.