Some women ask, “Why do I get pelvic inflammatory disease even though I usually pay close attention to hygiene? Because the female reproductive system is completely separate from the urinary system, the outside of the reproductive system is connected to the outside world through the vaginal opening, and the inside is connected to the pelvic and abdominal cavities through the opening of the fallopian tubes. On the one hand, the vaginal opening is large, so germs from outside can easily enter and cause inflammation, and on the other hand, the vagina itself is resident to many pathogenic bacteria, which are normally peaceful when the immunity is good, but when the immunity decreases, these pathogenic bacteria will rise and cause inflammation. There are four main causes of pelvic inflammatory disease: a. Not paying attention to hygiene during menstruation: During menstruation, the endometrium peels off, the blood sinuses in the uterine cavity open, and there are clots present, which are good conditions for bacteria to thrive. If you do not pay attention to hygiene during menstruation, use sanitary napkins or toilet paper with substandard hygiene standards, or have sex, you will give bacteria the opportunity to retrograde infection, leading to pelvic inflammatory disease. Infection after childbirth or miscarriage: Patients are weak after childbirth or miscarriage, and the cervical opening has not yet closed well after dilatation, so the bacteria present in the vagina and cervix may infect the pelvis upstream at this time. Third, infection after gynecological surgery: abortion, IUD or IUD removal, tubal lavage, tubal imaging, endometrial polyp removal, or submucosal fibroid removal, if the sterilization is not strict or the original reproductive system is chronically inflamed, it may cause postoperative infection. Some patients do not pay attention to personal hygiene after surgery, or do not comply with medical advice after surgery, and resume sexual life prematurely, the same can make bacteria upstream infection, causing pelvic inflammatory disease. The most common is when appendicitis and peritonitis occur, as they are adjacent to the female internal reproductive organs, inflammation can spread through direct and cause inflammation in the female pelvis. When suffering from chronic cervicitis, inflammation is also able to pass through the lymphatic circulation and cause pelvic connective tissue inflammation.