Endometriosis is a condition where tissue resembling the uterine lining (endometrium) grows outside the uterine cavity, most commonly within the pelvis. This misplaced tissue responds to hormonal cycles, causing irritation, scarring, and adhesions. Endometriosis is a recognized cause of infertility, affecting an estimated 30% to 50% of women who experience difficulty conceiving. This raises a complex question: does surgically removing this abnormal tissue actually improve the quality of the eggs produced by the ovaries?
How Endometriosis Affects Ovary Health
Endometriosis creates a detrimental environment within the pelvis, directly impacting the health of eggs and surrounding ovarian tissue. Lesions shed blood and inflammatory substances into the peritoneal cavity, leading to chronic inflammation. This results in high concentrations of inflammatory molecules, such as cytokines like IL-8 and prostaglandin E2, within the fluid that bathes the ovaries and follicles.
The inflammatory process also triggers increased oxidative stress, an imbalance between harmful free radicals and protective antioxidants. This toxic microenvironment is thought to disrupt the function of granulosa cells, which are the cells that nurture the developing egg. Oxidative damage can impair the egg’s mitochondrial function (the cell’s energy source), leading to lower maturity rates and morphological abnormalities in retrieved oocytes. Ultimately, this constant exposure to inflammatory and oxidative agents compromises the egg’s quality before it even leaves the ovary.
Surgical Approaches to Endometriosis Excision
Surgical intervention is performed to remove the lesions and restore normal pelvic anatomy, primarily through a minimally invasive procedure called laparoscopy. Conservative surgery aims to remove the disease while preserving the reproductive organs. The two primary techniques used to eliminate the implants are excision and ablation.
Excision involves meticulously cutting out the endometrial lesions and underlying tissue, ensuring complete removal of the disease. This method is generally favored for deep infiltrating endometriosis and for ovarian endometriomas, which are cysts filled with old blood. Ablation, conversely, uses heat or laser energy to burn or vaporize the lesions on the surface. While effective for very superficial implants, ablation may leave deeper portions of the disease intact, potentially leading to quicker recurrence.
Impact of Surgery on Egg Quality and Ovarian Reserve
The direct effect of surgery on egg quality is challenging to measure, but removing inflammatory lesions aims to detoxify the ovarian environment. By excising the source of inflammation and oxidative stress, surgery may create a healthier follicular fluid, which is theorized to improve the developmental potential of the oocytes. Studies on eggs retrieved during IVF cycles suggest that women with endometriosis have a lower yield of mature oocytes, a metric that could potentially be improved by removing the disease.
The procedure carries a significant trade-off, particularly when removing ovarian endometriomas. An endometrioma itself decreases ovarian reserve, a measure of the remaining egg supply often assessed by Anti-Müllerian Hormone (AMH) levels. However, the surgical removal of the cyst wall, known as a cystectomy, can unintentionally strip away healthy ovarian cortex tissue that contains dormant follicles. This mechanical damage can lead to a further, measurable decline in AMH levels post-surgery, essentially reducing the total number of eggs available, even if the quality of the remaining eggs is theoretically improved.
Fertility Outcomes Following Endometriosis Removal
The ultimate goal of surgery for many women is a successful pregnancy, and clinical data show mixed but encouraging results. For women with minimal or mild endometriosis, surgical treatment has been shown to increase the chance of natural conception compared to no treatment. Following surgery, a significant portion of women are successful, with natural conception rates often reported between 45% and 75% within two years.
For moderate to severe disease, the benefit is often less clear and must be weighed against the risk of reducing ovarian reserve. Surgery is highly beneficial for improving access to the fallopian tubes and ovaries by removing scar tissue and adhesions, which physically impede fertilization. In cases of severe disease, conception rates post-surgery can still be around 73% in specialized centers, with a median time to conception of approximately 12 months. These outcomes emphasize that while egg quality is a factor, the surgical restoration of pelvic anatomy is a major contributor to improved fertility.