Background: Pelvic inflammatory disease (PID) is one of the most common infections between women during reproductive age which is associated with major long-term complication, including tubal factor infertility, ectopic pregnancy, and chronic pelvic pain. In addition, treatment of acute PID and its sequelae impose health care costs. Prevention of these long-term complications is dependent on clinicians having a high level of recognition in order to make an early diagnosis and improvement of treatment strategies based on knowledge of the microbiologic etiology of acute PID.

Methods: This is a systematic review of more than 2580 papers about the etiology of pelvic inflammatory disease, which had been published until 2012.

Results: In most cases, PID is a polymicrobial infection and of sexually transmitted organisms Neisseria gonorrhoeae and Chlamydia trachomatis were most prevalent. Recently Mycoplasma genitalia are known as a cause of acute PID. Treatment regimen for acute PID should be covered a wide variety of drugs against these microorganisms.

Conclusion: Determining risk factors and patients’ clinical symptoms play a vital role in diagnosis, treatment and prevention of PID, leading a decrease in disability rate and side effects of PID.