United States, PID is estimated to affect about one million people each year. A type of intrauterine device (IUD) known as the Dalkon shield led to increased rates of PID in the 1970s. Current IUDs are not associated with this problem after the first month. Signs and symptoms Symptoms in PID range from none to severe. If there are symptoms, fever, cervical motion tenderness, lower abdominal pain, new or different discharge, painful intercourse, uterine tenderness, adnexal tenderness, or irregular menstruation may be noted. Other complications include endometritis, salpingitis, tubo-ovarian abscess, pelvic peritonitis, periappendicitis, and perihepatitis. Complications PID can cause scarring inside the reproductive system, which can later cause serious complications, including chronic pelvic pain, infertility, ectopic pregnancy (the leading cause of pregnancy-related deaths in adult females), and other complications of pregnancy. Occasionally, the infection can spread to the peritoneum causing inflammation and the formation of scar tissue on the external surface of the liver (Fitz-Hugh–Curtis syndrome). Cause Chlamydia trachomatis and Neisseria gonorrhoeae are common causes of PID. However, PID can also be caused by other untreated infections, like bacterial vaginosis. Data suggest that PID is often polymicrobial. Isolated anaerobes and facultative microorganisms have been obtained from the upper genital tract. N. gonorrhoeae has been isolated from fallopian tubes, facultative and anaerobic organisms were recovered from endometrial tissues. The anatomical structure of the internal organs and tissues of the female reproductive tract provides a pathway for pathogens to ascend from the vagina to the pelvic cavity thorough the infundibulum. The disturbance of the naturally occurring vaginal microbiota associated with bacterial vaginosis increases the risk of PID. N. gonorrhoea and C. trachomatis are the most common organisms. The least common were infections caused exclusively by anaerobes and facultative organisms. Anaerobes and facultative bacteria were also isolated from 50 percent of the patients from whom Chlamydia and Neisseria were recovered; thus, anaerobes and facultative bacteria were present in the upper genital tract of nearly two-thirds of the PID patients. PCR and serological tests have associated extremely fastidious organism with endometritis, PID, and tubal factor infertility. Microorganisms associated with PID are listed below. Cases of PID have developed in people who have stated they have never had sex. Bacteria Chlamydia trachomatis Neisseria gonorrhoeae Prevotella spp. Streptococcus pyogenes Prevotella bivia Prevotella disiens Bacteroides spp. Peptostreptococcus asaccharolyticus Peptostreptococcus anaerobius Gardnerella vaginalis Escherichia coli Group B streptococcus α-hemolytic streptococcus Coagulase-negative staphylococcus Atopobium vaginae Acinetobacter spp. Dialister spp.