Endometriosis is a condition where tissue similar to the uterine lining develops outside the uterus; it ‘bleeds’ during periods, forms lesions, and causes chronic pain. Despite affecting around 10% of menstruating people, its aetiology is poorly understood, and diagnostics and treatments are highly inadequate. Current efforts to reconceptualise the disease generally centre around inflammation. In this Field Note I describe my fieldwork during the pandemic, which was largely based on in-depth interviews with patients and clinicians in and around Edinburgh, Scotland. This research interrogates the socio-cultural context in which endometriosis is changing from a ‘gynaecological disorder’ to a ‘systemic disorder’ implicating the endocrine system (a ‘hormonally driven condition’), the neural system (‘neuropathic pain’) and/or the immune system (an ‘inflammatory condition’). It explores how the lived experience of endometriosis challenges ingrained ways of thinking about the body and bodily ‘systems,’ which are reflected in the design of healthcare systems. Considering endometriosis alongside changing conceptions of immune response invites thinking beyond self-versus-non-self (as in older concepts of immunity), and self-attacking-self (as in auto-immune conditions), to something like ‘self-out-of-place,’ simultaneously calling into question the suitability of our social and material relations.