AMH (anti-mullerian hormone) is produced by the granulosa cells of the ovary, regulates folliculogenesis and its levels are believed to accurately reflect the ovarian reserve. Various studies have suggested that patients with endometriosis have lower AMH levels compared to those without (controls). Furthermore, surgery for endometriosis may (at least temporarily) impact on AMH levels. So, what does the actual evidence suggest?

Let us start by saying that AMH levels are not predictive of a woman’s future fertility, since they do not predict the chances of natural conception, based on the existing evidence. The true value of AMH levels is to predict the ovarian response following ovarian stimulation, as part of IVF protocols. AMH levels tend to decline with advancing age and may be predictive of the age at natural menopause.

Let us remember that three phenotypes of endometriosis are recognised: superficial peritoneal endometriosis, ovarian endometrioma and deep endometriosis. Regarding superficial endometriosis, although it is linked to infertility, evidence is less clear regarding its impact on AMH levels, with some studies suggesting AMH levels are lower. On the other hand, there is overwhelming evidence that patients with ovarian endometrioma and deep endometriosis have lower AMH levels compared to controls. With regards to ovarian endometrioma, there is also a higher rate of AMH decline over time.

Severity of endometriosis also appears to have a negative impact on AMH levels, with those suffering from stage 4 disease, exhibiting diminished levels compared to patients with ‘’milder’’ disease. This may seem reasonable, taking into account that pregnancy rates tend to decline as the severity of endometriosis increases.

It is worth considering the actual effect of endometriosis surgery on AMH levels: as regards superficial endometriosis, its surgical excision does not appear to significantly reduce AMH levels. Regarding ovarian endometrioma, the vast majority of studies have demonstrated a reduction in AMH levels post-surgery, although these may recover to levels similar to pre-operative, as time passes after surgery. Factors that may influence on the rate of decline include surgical technique used, size of endometrioma, bilaterality, previous surgeries, patient age and pre-operative AMH levels.

Can pre-operative AMH levels predict the chances of pregnancy after endometriosis surgery? The definition of low AMH levels is not universally agreed, with most studies suggesting that it should be considered low if less than 2 ng/Ml. Based on the existing evidence for cases of ovarian endometrioma, a low AMH value before surgery may negatively impact on the chances of conception after endometrioma surgery, however, there is no sound evidence regarding an association between pre-operative AMH levels and actual livebirth rates. Regarding other endometriosis phenotypes, evidence is limited, with a single study of young patients with an average age of 30 years and deep endometriosis of the bowel, not finding an association between low AMH levels and post-operative conception rates.

If you suffer (or you think you may suffer) from endometriosis, do not hesitate to contact us for more information and/or to book an appointment!