Pelvic effusion with severe back pain is usually caused by pelvic inflammatory disease. Gynecologic ultrasound and gynecologic examination are needed to further clarify the diagnosis. If the gynecological ultrasound does not reveal any organic lesion, and the gynecological examination shows pressure pain in the uterine area and pressure pain in the bilateral adnexal area. This situation can be diagnosed as pelvic inflammatory disease, which needs to be treated with oral antibiotic drugs. Generally, cephalosporin antibiotics combined with metronidazole antibiotics can be used for treatment. You can also choose anti-inflammatory drugs of Chinese medicine nature, such as Pu Ling pelvic inflammatory health, anti-women’s inflammatory capsule, uterine inflammatory pills, etc. If the symptoms are not relieved by the above treatment, you can switch to intravenous drip antibiotic drug treatment, you can choose metronidazole antibiotics combined with cephalosporin antibiotics and other treatment.