Pelvic inflammatory disease (PID) represents the most important cause of chronic reproductive morbidity in young women, with over 1.25 million cases diagnosed annually in the United States. The term PID is used to described a sexually transmitted infection involving the uterus, ovaries, and peritoneal tissues as well as the fallopian tubes and leading to ectopic pregnancy and/or involuntary infertility. Risk factors that may predispose young women to develop acute PID include (1) youth, with sexually active female adolescents diagnosed three times more frequently than 25- to 29-  year olds; (2) endocervical STD infection, especially C. trachomatis and N. gonorrhoeae (other vaginal flora, eg, anaerobes, G. vaginalis, H. influenzae, enteric gram-negative rods, Streptococcus agalactiae, M. hominis, and U. urealyticum have been implicated); (3) previous gonococcal salpingitis resulting in tubal damage, which may predispose to recurrent episodes of infection; (4) sexual behaviors, such as a number of sexual partners, that place women at increased risk for STD infection; (5) intrauterine devices (IUDs), which are associated with a two- to fourfold increase in PID and the presence of which encourages the development of a local endometritis; and (6) recent gynecologic interventions, eg, therapeutic abortion or endometrial biopsy. Although the relationship of oral contraceptives to acute PID has been controversial, most current research supports a protective role of oral contraceptives in the development of PID.

Pathogenesis
The proposed pathogenesis of PID involves ascending canalicular spread of the causative sexually transmitted agent(s) from the vaginocervical compartment during sexual intercourse. The organisms pass through the mechanical and immunologic barriers of the endocervix, along the endometrial surface to the tubal mucosa, and finally onto peritoneal surfaces by leakage from the tubal fimbria. Modes of transport are discussed above.

Diagnosis and Treatment
Symptoms and signs of acute PID include lower abdominal pain, vaginal discharge, cervical motion tenderness, and uterine and adnexal tenderness (

Table 3-18). Only about 60% of cases are correctly diagnosed, based on verification by laparoscopy. The differential diagnosis to be considered in a young woman presenting with acute lower abdominal pain, in addition to PID, includes acute appendicitis, acute cystitis, acute cholecystitis, acute pyelonephritis, ectopic pregnancy, endometriosis, hemorrhagic ovarian cyst, intrauterine pregnancy, mesenteric lymphadenitis, ovarian cyst with or without torsion, ovarian tumor, septic abortion, severe constipation, and trauma. Because laparoscopy is not warranted in most cases to define PID, reliance must be placed on an accurate sexual history and application of clinical criteria (

Table 3-18).

Principles to remember in the clinical approach to PID include these: (1) rule out pregnancy; (2) use the standardized clinical criteria to guide, not dictate, the diagnosis; (3) err on the side of “overdiagnosis” of PID when in doubt to prevent sequelae, especially in view of the possibility of subclinical chlamydial infections; (4) treat with broad-spectrum antibiotics and begin the course immediately on diagnosis; and, finally, (5) follow up with clinical evaluations (within 24 to 48 hours) to confirm the original clinical diagnosis and reevaluate the treatment regimen. Treatment regimens are outlined in

Table 3-19. Criteria for hospitalization include all adolescents; uncertain diagnosis; presence of a pelvic or tuboovarian abscess; pregnancy; severe illness, nausea, and vomiting; inability to take oral medications; failure of outpatient therapy within 48 hours; inability to arrange follow-up within 72 hours of starting antibiotics; and patient being HIV-positive. A major serious complication to acute PID is the development of a tuboovarian abscess. Although most abscesses can be managed medically, occasional surgical intervention is necessary when medications fail. Screening and treatment of the sexual partner is an important part of PID management, as with any STD.