Myometrial Physiology and Its Relation to Pelvic Pain

Many factors contribute to the presence of pelvic pain during menstruation. Attention in the present paper will be devoted primarily to the myometrium, though the person as a unit must always be considered. The present knowledge concerning human nonpregnant uterine contractions is based on extensive investigations on experimental animals supplemented by careful clinical observations and uterine pressure records from control, pregnant and dysmenorrheal patients. Intrauterine pressure records from the nonpregnant human uterine were first obtained by Moir, 1 who observed during menses that contractions occurred every two minutes and developed pressures as high as 100 mm. of mercury. No pain but a feeling of heaviness and discomfort occurred when uterine pressures of 120 mm. of mercury were present. In patients with severe dysmenorrhea, pressures of 150 mm. of mercury were recorded and vascular pulsations disappeared at 120 mm. of mercury. Bickers 2 showed that high uterine tone is associated with