The concept of lower genital tract infection with chlamydia or gonorrhoea causing cervicitis and vaginal discharge is familiar to most sexual health physicians. Likewise, upper genital tract infection with inflammation of the fallopian tubes and adnexae in the form of pelvic inflammatory disease (PID) is also a common clinical syndrome with well recognised implications for future fertility. It is assumed that most PID develops secondary to the spread of infection from the lower genital tract, through the uterine cavity into the upper genital tract. What is less certain, and where no clear guidance is currently available, is whether this intermediate step of endometritis is a distinct clinical condition in its own right and, if so, how it should be diagnosed and treated.

Endometritis is a pathological diagnosis with infiltration of the normal vascular architecture by inflammatory cells. Agreeing a precise histological definition of endometritis is difficult since a variety of different features are seen—the inflammatory infiltrate may be confined to the surface epithelium or spread more deeply into the stroma; inflammatory cells may comprise neutrophils and/or plasma cells; and lymphoid aggregates or subepithelial haemorrhages have also been reported. The features which correlate most closely to “true” PID are the presence of both neutrophils and plasma cells, leading to the most commonly accepted definition of endometritis which is five or more neutrophils per 400 power field in the superficial endometrium, in addition to one or more plasma cells per 120 power field in the endometrial stroma.¹

Sampling of the endometrium is usually performed using a endometrial suction biopsy …