A 2026 review explored why endometriosis surgery doesn’t always lead to pregnancy, highlighting factors like recurrence, undetected lesions, and underlying biological processes that aren’t addressed by surgery.
Endometriosis involves the growth of endometrial-like tissue outside the uterus and can cause inflammation and adhesions that are linked to infertility. Surgery is commonly used to remove these lesions in hopes of improving pregnancy chances.
In some cases, surgery can help, but many patients go through surgery and still have problems trying to conceive.
In their review, Pirtea et al. (2026) offer explanations for why surgery doesn’t always lead to pregnancy.
🔗 Original studies are referenced in this post or within the linked Remembryo posts.
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The limits of endometriosis surgery for fertility
Even when surgery is technically successful, many of the processes linked to infertility either remain in place or return over time.
Microscopic endometriosis. Some endometriosis lesions are too small to be seen during surgery. In one study, only about 11–12% of patients had visible endometriosis on the fallopian tubes, but over 40% had microscopic involvement when the tissue was examined more closely, suggesting a large amount of endometriosis can go undetected during surgery (McGuinness et al. 2020). While they have been shown to exist and might explain why surgery doesn’t always work , it’s not clear how much these microscopic lesions contribute to infertility or whether removing them improves outcomes.
Surgeons may miss lesions. It’s not always easy to clearly identify every lesion. Some lesions are subtle or located in areas that are hard to see or reach, so not all areas are always removed.
Retrograde menstruation. One of the main theories behind endometriosis is that menstrual tissue flows backward into the pelvis. Some research suggests it’s not just the cells themselves, but also the blood that plays a role. Iron from this blood can create oxidative stress and inflammation, which may damage surrounding tissue and make it easier for endometrial-like cells to implant and grow (Vercellini et al. 2024). This process continues after surgery, which means the underlying process that contributes to inflammation and lesion formation isn’t corrected, and may continue to affect fertility.
Adhesions frequently reform. Adhesions are part of the body’s natural healing response to inflammation or surgical trauma, so even after they’re removed, the repair process itself can create new scar tissue. They can form sticky bands that bind pelvic organs together, like the ovaries, fallopian tubes, uterus, bladder, and bowel. This can limit their movement, which could also contribute to the pelvic pain commonly seen with endometriosis. They’ve been found in more than half of patients within weeks to months after pelvic surgery, and in some cases can form in up to 70 to 100% of patients depending on the procedure (Malin et al. 2025).
Recurrence over time. Endometriosis can return after surgery. Recurrence rates are estimated at 21.5% after two years and 40-50% after five years (Guo 2009). This likely happens because some lesions or cells are left behind, microscopic endometriosis goes undetected, or new lesions form over time. Postsurgical hormonal therapy, such as GnRH agonists or oral contraceptives, may help reduce recurrence and slightly improve pregnancy rates, but overall evidence is still uncertain and depends on timing relative to surgery (Chen et al. 2020).
Contributing conditions. Endometriosis is often linked with other conditions like fibroids (Fiore et al. 2025), polyps, uterine abnormalities, and especially adenomyosis (de Ziegler et al. 2023). These can also affect fertility and aren’t corrected by removing endometriosis alone. In their meta-analysis, Cozzolino et al. (2022) showed that adenomyosis can reduce live birth rates after IVF significantly.
Medications for pain. Many endometriosis patients use pain medications like NSAIDs or opioids. These can sometimes affect ovulation, implantation, or sexual function, which may also play a role (McInerney et al. 2016).
Other biological factors that surgery doesn’t address
- Chronic inflammation and immune dysfunction. Endometriosis is linked to ongoing inflammation and altered immune activity, which may affect fertilization, embryo development, and implantation. These changes may also allow lesions to form and persist (Blanco et al. 2025).
- Environmental exposures. Certain chemicals, like BPA and phthalates, may disrupt hormones and promote inflammation, potentially contributing to how endometriosis develops and persists (Dutta et al. 2023).
- Altered uterine contractility. Uterine contractions can become stronger or uncoordinated, which may disrupt sperm transport and interfere with implantation (Salmeri et al. 2024).
- Genetic factors. Endometriosis has a genetic component, with many genes linked to hormone signaling, inflammation, and immune function, suggesting an underlying predisposition (Rahmioglu et al. 2023).
- Blood in the pelvis and lesion formation. Some research suggests that blood in the pelvic cavity, such as from a ruptured cyst, can create conditions that help lesions form. Blood clots may trap endometrial cells and trigger inflammation and fibrosis, which can lead to new lesions over time (Chaggar et al. 2024).
Conclusion
In the end, the issue may not be whether surgery works, but what it’s actually capable of fixing.
As the authors put it, “endometriosis is a systemic disease that can involve different biological systems beyond the mere gynecological organs.”
Surgery can remove what’s visible and may improve fertility for some patients, but it doesn’t always address the full picture. If it doesn’t lead to success, it doesn’t mean the surgery failed, instead it might simply mean that there are other factors at play.
Understanding this can help set more realistic expectations and guide next steps, whether that’s additional treatment, IVF, or a different approach moving forward.
Want to read more about endometriosis?
Researchers in a 2025 study showed that women with endometriosis or adenomyosis had lower IVF success overall after 3 IVF cycles, with more differences in the first, fresh transfer. Read more.
A 2025 study found that PCX, a surface molecule on endometrial cells, may lead to a shorter implantation window in women with endometriosis and might explain the stickiness of lesions outside the uterus. Read more.
A 2024 study combined studies involving unexplained infertility patients and endometriosis, finding that nearly half of them have the condition. Read more.
Laparoscopy is the gold standard for diagnosing endometriosis, but other non-surgical tests are showing potential. Here we'll take a brief look at ReciptivaDx based on the BCL6 protein, the Endotest and DotEndo test based on a miRNA signature, the EMScore which is based on a gene expression signature, and imaging tests like ultrasound and MRI. Read more.
Reference
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About Embryoman
Embryoman (Sean Lauber) is a former embryologist and the founder of Remembryo, an IVF research and fertility education website. After working in an IVF lab in the US, he returned to Canada and now focuses on making fertility research more accessible. He holds a Master’s in Immunology and launched Remembryo in 2018 to help patients and professionals make sense of IVF research. Sean shares weekly study updates on Facebook, Instagram, and Reddit regularly. He also answers questions on Reddit or in his private Facebook group.