The absence of menstruation but very sore back, may be certain physiological phenomena, may also be the manifestation of certain diseases, such as pelvic inflammatory disease, endometriosis, etc., should be timely consultation to identify the cause of the disease. 1. Physiological factors: women before menstruation, due to uterine contractions, often varying degrees of pain in the lower back, usually the pain is not severe, dysmenorrhea patients often before menstruation may be severe back pain. If you don’t have menstruation but your back is very sore, you can’t rule out the possibility of pregnancy, and it is recommended that you go to the hospital in time for a blood HCG test. 2. Pathologic factors: (1) Pelvic inflammatory disease, the most common symptom is abdominal pain, there may also be fever, lumbago, lumbago, leucorrhea and other symptoms. As pelvic inflammatory disease has the possibility of inflammatory exudation to the connective tissues next to the various tissues in the pelvis, causing symptoms such as lumbar acidity and lumbago. (2) Endometriosis is a series of symptoms caused by the planting of the growth-active endometrium in a location other than the uterine cavity. The ectopic endometrium can invade any part of the body, so it may be ectopic in the lumbosacral region, causing low back pain. This symptom alone cannot determine the disease, and other factors cannot be ruled out. It is recommended that if physiological causes are excluded, timely consultation should be made to clarify the cause of the disease and give targeted treatment.