Pelvic inflammatory disease (PID) is an inflammatory condition of the pelvic cavity that is usually caused by bacteria like gonorrhea and chlamydia. It begins with cervicitis and can spread to the uterus, fallopian tubes, ovaries, and pelvic peritoneum. Risk factors include young age, multiple sexual partners, history of STDs, and procedures like IUD insertion. Symptoms include lower abdominal pain and vaginal discharge. Diagnosis involves history, exam noting cervical motion tenderness, and tests. Treatment is hospitalization, IV antibiotics, and educating partners to prevent reinfection. Complications can include infertility, ectopic pregnancy, and chronic pelvic pain.