An effort to elucidate a subject which is laden with difficulties is noteworthy, so that it was interesting to read the report by Simms et al¹ on the associations between Mycoplasma genitalium, Chlamydia trachomatis, and pelvic inflammatory disease (PID). The difficulties are at least threefold. Firstly, a diagnosis of PID based on symptoms and clinical signs, as in the study reported, is acknowledged, both generally and by the authors, to be imprecise. …