Comparison with Existing Literature
Since the type of ovarian cyst may also impact the ovarian reserve29, 30, we categorized the studies into subgroups: those focused exclusively on endometriomas and those that examined various types of benign ovary cysts. Eight of the RCTs exclusively included only endometriomas 3, 16, 17, 20, 21, 24, 25. And the remaining five RCTs investigated patients with various types of benign ovary cysts 2, 4, 19, 22, 23. Previous studies indicated that endometriosis is also a risk factor for infertility, which might decrease ovarian reserve since the endometriotic cyst wall is formed by the invagination of the ovarian cortex31. A previous study found that the morphology pattern of the ovarian tissue adjacent to the endometrioma wall did not display standard follicular patterns. In contrast, the ovarian cortex surrounding other benign ovarian cysts is usually normal32.
Furthermore, Park et al. presumed that the ovarian reserve is more affected in patients with endometriomas, who tend to have pelvic adhesion. The vascular system within the ovarian cortex or surrounding the ovary could be injured during adhesiolysis 23. This might explain why the decline in serum AMH levels was more significant in the electrocoagulation group when comparing patients with endometriomas.
On the other hand, we found that the patients with benign ovarian cysts had a smaller decline in AMH and AFC after surgery, with no significant difference between the electrocoagulation group and nonthermal hemostasis group. We could surmise that if we exclude patients with endometrioma from overall patients with non-specific benign ovarian cysts, the result of the forest plot will show a shift to the left side, indicating a decreased effect size in favor of the nonthermal group, signifying no significant difference in AMH and AFC between the two groups, even in the long-term follow-up extending to 12 months. Since endometriomas inherently have an adverse impact on ovarian reserve, coupled with the significant detrimental effect of electrocoaguation during surgery in women with endometriomas, it is advisable to refrain from employing electrocoagulation using bipolar current. Additionally, surgeons should exercise caution to prevent injury to the ovarian cortex injury during surgeries for endometriomas.
AMH production initiates with the growth of primordial follicles into small antral follicles, a process that takes at least three months33. Thus, most studies 2-4, 16-20, 23, 24 measured AMH levels at the 3-month follow-up. We also compared outcomes at 1, 6, 12 months 3, 16, 17, 19, 21, 22, 24, 25, since the longer follow-up time allows for a more comprehensive understanding of the sustained change of AMH and AFC and addresses any immediate postoperative concerns. Some studies 3presumed that more primordial follicles might have started to grow to compensate for the acute ovarian damage after surgery. Therefore, the secretion of AMH from those newly developed follicles might lead to similar results in both treatment groups. Nonetheless, we didn’t find the decline of AMH and AFC by electrocoagulation in endometrioma patients to become normal after a long-term follow-up of 12 months. The results of this present study found no significant difference in the postoperative AMH and AFC between the two treatment groups at long-term follow-up to postoperative 12 months for patients with benign ovarian cysts 2, 4, 19, 23. However, the results showed the beneficial effect of nonthermal hemostatic agents on preserving ovarian reserve after surgery in endometrioma patients.
In order to investigate the long-term influence of the surgical hemostatic method on the ovarian reserve, we also analyzed the outcomes of postoperative 1, 3, 6, and 12 months. The impact on ovarian reserve would change over time. The AMH levels might decrease transiently or consistently after surgery 34. Previous papers have found a significant reduction in AMH levels in patients at 1- and 3-months post-surgery 35. However, the AMH levels in some of the patients might subsequently recover after a year36. Some studies3 presumed that more primordial follicles might have started to grow to compensate for the acute ovarian damage after surgery. The recovery of AMH is presumed to be associated with reperfusion of treated ovaries 37and folliculogenesis from primordial follicles to preovulatory follicles, which takes about 180 days 36. In Zhang’s17 and Chung’s24 studies, the mean AMH level of the two groups in endometrioma patients had not decreased during 3-12 months. However, the AMH level in the electrocoagulation group is still significantly lower than that of the nonthermal group at 12 months post-operation. Thus, we consider that electrocoagulation using bipolar current might have a sustained effect on the ovarian reserve in patients with endometrioma, which may act directly on destroying a substantial portion of primordial follicles.