1. Which factors on history and physical make you think a patient has more than cervicitis?
Greater than 90% of patients with PID present with bilateral, lower abdominal pain. Time of onset is similarly suggestive, with up to 75% of cases beginning in the first week after the onset of menstruation. While neither sensitive nor specific, 75% of PID patients will have new discharge, and half will have a fever. Obviously the presentation can vary, including manifold symptoms such as dysuria, vomiting, and back pain. The only physical findings that are routinely found (in > 90% of laparoscopically verified PID) are lower abdominal tenderness, adnexal tenderness, and cervical motion tenderness. No lab test is consistently useful in diagnosing PID (apart from a verified diagnosis of GC or CT), including CBC (only around 60% of PID patients have a WBC > 10,000). There is some data to suggest transvaginal ultrasound may aid diagnosis, but this is still an area of controversy. Bottom line: The criteria for diagnosis of PID are very subjective. Because of the important consequences of untreated PID (TOA, infertility), you should have a very low threshold to treat a woman with cervicitis as PID.
The most common outpatient regimen is doxycycline for fourteen days plus ceftriaxone or cefoxitin IM once. Inpatient regimens are most typically doxyccyline (IV/PO) plus an appropriate cephalosporin (ceftriaxone) or cephamycin (cefoxitin). Clindamycin and gentamicin are another inpatient option. Note that outpatient regimens for patients truly allergic to cephalosporins are limited. In terms of metronidazole, clearly those with concomitant bacterial vaginosis or trichomonas should receive it, but the CDC also recommends including it when there is a pelvic abscess (see question #3) and in anyone with a history of gynecologic instrumentation in the prior month.
3. What imaging do you order? When do you image?
PID does not require any imaging for diagnosis or management. However, the complications associated with PID, notably tubo-ovarian abscess (TOA), require imaging for diagnosis. For years, the standard teaching had been that ultrasound was the diagnostic modality of choice for the diagnosis of TOA. Retrospective studies noted sensitivities as high as 93% in the past. These studies basically looked at the rate of positive ultrasounds in patients with PID and a palpable adnexal mass. Unfortunately, this only represents a small subset of TOA patients. More recent literature has challenged these findings and suggests a more modest sensitivity, near 83%. The only prospective trial with a gold standard (laparoscopy) found that MRI had a sensitivity approaching 100% and a specificity of around 90%. Preliminary studies on CT scanning with IV contrast suggest a sensitivity in the mid to high 90% range but there is inadequate data at this time to definitively state the utility of CT in this diagnosis.
4. Which patients do you admit?
Currently, only 15-25% of women diagnosed with PID are hospitalized. The CDC guidelines recommend it when: (1) the diagnosis is uncertain, (2) the possibility of surgical emergencies such as appendicitis and ectopic pregnancy cannot be excluded, (3) a pelvic abscess is suspected, (4) the patient is pregnant, (5) the patient is an adolescent, (6) severe illness precludes outpatient management, (7) the patient is unable to follow or tolerate an outpatient regimen, (8) the patient has not responded to outpatient therapy, or (9) clinical follow-up cannot be arranged within 72 hours of the initiation of antibiotic treatment.
References and Further Reading: