Pain is more than a physical stimulus from an anatomical location
The theory that endometriosis has a multifactorial pathogenesis could explain why endometriosis remains difficult to classify regarding prognosis and clinical correlation. This multifactorial pathogenesis includes endometriosis severity (stage, location, depth of invasion), co-morbidity conditions, myofascial factors (muscle and fascial involvement), and central sensitisation (17). According to the International Association for the Study of Pain, the definition of pain is “an unpleasant sensory and emotional experience associated with actual or potential tissue damage”. Besides, it has become more clear that pain experience is also influenced by psychological factors (e.g. catastrophising, anxiety, coping) (18, 19) and central sensitisation (persistent state of high reactivity) (20). This supports the theory that not only the severity of the endometriosis is responsible for pain symptoms. Endometriosis lesions on anatomical structures are not solely responsible for the pain sensation: it seems far more complex than that.