Endometriosis Surgery and Fertility Outcomes: An Evidence-Based Review

INTRODUCTION

Endometriosis affects approximately 10% of women of reproductive age and is a well-established cause of infertility. The condition impairs fertility through multiple mechanisms, including distorted pelvic anatomy, chronic inflammation, hormonal imbalances, and reduced ovarian reserve. While medical management can alleviate symptoms, surgery is often indicated for women seeking to conceive, particularly when endometriosis is associated with anatomical distortion or ovarian endometrioma. This review discusses the impact of different surgical techniques on fertility outcomes, evaluating the balance between improving conception rates and preserving ovarian function.

SURGICAL APPROACHES FOR ENDOMETRIOSIS AND THEIR IMPACT ON FERTILITY

Over the years, surgery has been one of the most admired modalities to achieve fertility, especially in low-resource settings with limited access to assisted reproductive techniques (ART). Pelvic adhesions are a common consequence of endometriosis and contribute significantly to infertility. Laparoscopic adhesiolysis aims to restore normal tubal function and pelvic anatomy, facilitating spontaneous conception. Studies indicate that fertility outcomes improve significantly after laparoscopic surgery, with pregnancy rates ranging from 30% to 50% within 1 year post-surgery.

Laparoscopy is generally favoured over open surgery for the treatment of endometriosis, as it provides enhanced visualisation of lesions along with the recognised advantages of minimally invasive techniques. These additional benefits include faster recovery, reduced postoperative pain and better cosmetic outcomes.^[1]

Despite advancements in surgical techniques, the effectiveness of laparoscopic surgery for peritoneal endometriosis [American society for reproductive medicine (ASRM) stage I–II] in improving pregnancy rates among infertile patients remains a subject of debate. Although the precise mechanisms by which laparoscopic removal of endometriotic lesions improves fertility remain uncertain, current evidence indicates a potential benefit. According to a recent Cochrane review, laparoscopic intervention is associated with a higher rate of viable intrauterine pregnancy compared to diagnostic laparoscopy alone (OR 1.89, 95% CI 1.25–2.86; three randomized controlled trial (RCTs), 528 participants; I² = 0%).^[2] Therefore, the European Society of Human Reproduction and Embryology (ESHRE) recommends offering laparoscopy to women with endometriosis-related subfertility.

Previous Cochrane reviews concluded that ablation of endometriosis, which destroys lesions using thermal energy, has been associated with higher recurrence rates and less effective fertility restoration, whereas excision involving the complete removal of endometriotic lesions reduces inflammatory cytokine levels and improves fertility outcomes. However, current evidence suggests comparable outcomes with both laparoscopic excision and coagulation in the treatment of early-stage endometriosis.

OVARIAN ENDOMETRIOMA SURGERY

Ovarian endometrioma, present in approximately 40% of women with endometriosis. They are associated with reduced ovarian reserve. It is not only due to its space-occupying nature but also due to oxidative stress reactions causing loss of cortical stroma and impaired vascularisation, resulting in follicular atresia.^[3] Additionally, endometrioma can cause dyspareunia, which leads to infrequent coitus and impaired sexual function.^[4,5] Surgical management options include cystectomy (complete excision of the cyst wall) and drainage with ablation. For ablation, different types of energy devices can be used. Commonly used types of energy are electro-thermal energy, plasma energy and lasers.

Overall, when the pregnancy rates are compared, cystectomy and argon plasma ablation had a significant pregnancy rate of around 30%. In comparison, pregnancy rates following simple drainage were significantly lower.^[6,7] While cystectomy lowers recurrence rates and enhances natural conception, it also carries the risk of reducing ovarian reserve by inadvertently removing healthy ovarian tissue.^[8] Studies show a significant decline in Anti-Müllerian Hormone (AMH) levels around 30% post-cystectomy, highlighting the need for careful surgical planning.^[8] Excision of large endometriomas (>7 cm) and bilateral cysts has the greatest detrimental effects.^[9–11]

As a rule of thumb, before surgical interventions for endometrioma, ovarian reserve assessment using AMH levels and Antral Follicle Count is recommended.^[7,12] Strategies to preserve fertility include meticulous haemostasis, ovarian suturing techniques, and consideration of oocyte cryopreservation before surgery in high-risk cases.^[12] Patient counselling and education prior to those techniques are very important, including that the number of vitrified oocytes and age predict the live birth rate.^[13]

Vasopressin can be used during endometrioma cystectomy, given that it reduces bleeding and preserves ovarian reserve. Though few randomised controlled trials have shown its benefit in reducing bleeding and obtaining clear margins in resection of the cyst wall using hydrodissection, many state there is no significant improvement in spontaneous pregnancy rates or preserving ovarian reserve.^[14]

Therefore, treatment for endometrioma in the background of subfertility is still in a dilemma. One commonly used and proven method to improve AMH levels is a three-stage procedure (cyst drainage laparoscopically, downregulating with gonadotropin releasing hormone (GnRH), and a second laparoscopic surgery for cystectomy).^[15,16] Plasma ablation is an upcoming technique using advanced energy devices.

DEEP INFILTRATING ENDOMETRIOSIS (DIE) AND SURGERY

Endometriosis tends to infiltrate various anatomical sites to differing extents. This makes surgery for endometriosis very challenging. These surgeries are some of the most technically demanding procedures in gynaecologic surgery. Ensuring safe and effective surgical outcomes requires strict adherence to fundamental surgical principles. A structured approach is essential, not as a rigid checklist but as a guiding framework that provides consistency and adaptability based on intraoperative findings and surgical complexity.

DIE affects structures such as the rectum, bladder, and ureters, leading to severe pain and infertility. While radical excision can relieve symptoms and restore normal pelvic anatomy, its impact on fertility is debated.^[17] Some studies indicate improved natural conception rates post-surgery, while others suggest that ART remains necessary in severe cases.^[18,19] The ESHRE guideline committee recommends surgery in DIE for symptomatic patients who have fertility wishes.^[7]

SURGICAL OUTCOMES AND ASSISTED REPRODUCTIVE TECHNOLOGY (ART)

Surgical intervention, particularly laparoscopic excision or ablation of endometriotic lesions, has been shown to improve fertility outcomes in women with minimal to mild endometriosis (stages I/II). A meta-analysis of randomised controlled trials demonstrated that operative laparoscopy in these patients increased spontaneous pregnancy rates within the first year post-surgery compared to diagnostic laparoscopy alone.^[20]

Natural conception rates are highest within the first 6–12 months post-surgery, after which ART may be considered.^[21] The efficacy of surgical intervention in enhancing natural conception rates varies based on the severity of endometriosis. Therefore, the decision to perform surgery should be individualised, considering factors such as patient age, ovarian reserve, and symptomatology.^[22]

SURGERY BEFORE IN-VITRO FERTILISATION (IVF): NECESSARY OR NOT?

The necessity of surgical intervention before initiating IVF treatment is a subject of ongoing debate. For Stage I-II Endometriosis, IVF success rates remain comparable between surgical and non-surgical groups; hence, surgery is not always required before ART. In Stage III-IV endometriosis, surgery is beneficial in severe cases to remove large endometriomas (>5 cm) and deeply infiltrating endometriotic lesions.

Current guidelines suggest that surgery for ovarian endometrioma before ART should be considered primarily to improve endometriosis-associated pain or to enhance access to follicles during oocyte retrieval, rather than to improve fertility outcomes.^[21] Surgery, particularly cystectomy for endometrioma, may reduce ovarian reserve. Due to the potential negative impact on ovarian reserve, routinely operating on endometrioma prior to ART is not recommended.^[21]

Pregnancy rates following excision of deep endometriosis with and without bowel involvement have been reported to be around 20%–30% and 50%, respectively, in two systematic reviews.^[20] A review that focused specifically on spontaneous conception after surgery for DIE reported a mean conception rate of 24%.^[22]

A meta-analysis of several observational studies showed that the live birth rates doubled with IVF following surgery compared with IVF only; however, no RCTs have confirmed this benefit.^[23]

THE ROLE OF HORMONAL SUPPRESSION POST-SURGERY

Post-surgical hormonal suppression using GnRH agonists has been proposed to enhance fertility outcomes by reducing residual inflammation and improving endometrial receptivity.^[24] GnRH agonists (e.g., leuprolide 3.75 mg IM monthly or 11.25 mg every 3 months) are preferred for postoperative suppression for 3–6 months.^[25] GnRH antagonists (e.g., Cetrorelix 0.25 mg daily or Elagolix 150 mg daily) have also been studied, but evidence on their superiority over agonists is limited. Medroxyprogesterone acetate (5–10 mg daily) or dienogest (2 mg daily) can be used as alternatives to GnRH agonists for suppression.^[25] A monophasic combined oral contraceptive pills (COCP) containing ethinyl oestradiol 30–35 mcg with a progestin component (e.g., norethindrone 1 mg or drospirenone 3 mg) taken continuously for 3–6 months postoperatively may reduce recurrence but has a limited impact on fertility.^[24]

WHAT IS THE OPTIMAL TIME FOR ART FOLLOWING SURGERY?

To optimise outcomes, ART should be initiated within 6–12 months post-surgery to maximise success rates, as fertility decline resumes over time. Hormonal suppression post-surgery has been shown to improve IVF pregnancy rates by 10–15%, and IVF should be initiated immediately after cessation of hormonal therapy, as delaying beyond 6 months may reduce ovarian responsiveness.^[24]

FUTURE DIRECTIONS IN ENDOMETRIOSIS SURGERY

The efficacy of repeat surgical intervention in endometriosis-associated infertility is a subject of ongoing debate, with pregnancy rates ranging from 28.6% to 54% across both spontaneous and ART-assisted conceptions.^[26,27] However, when fertility is the primary goal, available evidence indicates diminishing returns with subsequent procedures. A review by Berlanda et al. indicated that pregnancy rates following repeat surgery were between 20% and 26%, compared to 30% with ART and 41% following initial surgical intervention.^[28,29]

Given the high prevalence of minimal/mild endometriosis (MME) in cases of unexplained infertility, alongside evidence supporting the effectiveness of laparoscopic treatment in improving fecundity and live birth rates, the authors highlight the need for a non-invasive diagnostic tool to accurately identify MME. Identifying and surgically treating MME at an earlier stage may reduce the dependence on assisted reproductive technologies.

Although the ASRM classification system is valuable for staging disease severity, its use in predicting fertility outcomes post-surgery remains limited. In contrast, the Endometriosis Fertility Index was specifically developed to estimate spontaneous pregnancy rates following surgical treatment of endometriosis.^[30] This index serves both to reassure patients with a favourable prognosis for natural conception and to assist in identifying those who may benefit from early referral to assisted reproductive technologies (ART), thereby minimising delays in effective fertility management. Its clinical utility is supported by high inter-expert agreement and consistent predictive performance, as evidenced in recent systematic reviews and meta-analyses.^[31]

The authors hypothesise that the following advances in minimally invasive surgical techniques would further improve the outcome.

• Single-incision laparoscopy to offer improved cosmetic outcomes and potentially reduced postoperative pain.

• AI-assisted imaging may enhance the detection and classification of endometriotic lesions intra-operatively.

• Laser-assisted technique will lead to minimal thermal damage to ovarian tissue.

• Regenerative medicine approaches, such as research into stem cell therapy and platelet-rich plasma for ovarian rejuvenation, may have a role to play in the future.

CONCLUSION

Surgical management of endometriosis plays a vital role in improving fertility outcomes by restoring normal pelvic anatomy and enhancing spontaneous conception rates. While laparoscopic excision remains the gold standard, careful consideration of ovarian reserve preservation and individualised treatment planning is essential. Future advancements in minimally invasive surgery and regenerative approaches may further optimise fertility outcomes for women with endometriosis. More high-quality randomised trials are needed to refine surgical strategies and establish evidence-based guidelines for optimising reproductive success.