How common is it for somebody to get pelvic inflammatory disease?

PID part 1: Younger, sexually active women who have many different sexual partners and do not use barrier protection are at higher risk for pid. Many bacteria are causative, & pid can be asymptomatic or severely painful, mimicking appendicitis. Incidence is not clearly known but guessed to be about 1% of women of child bearing age. The picture is how pid looks inside the pelvis in a very severe case.

PID part 2: Pid is really an std. All the organisms that cause pid are std's. Therefore, protection against std is the best prevention from acquiring pid.