Pelvic Inflammatory Disease: Diagnosis and Treatment
Diagnosis
PID should be suspected when spontaneous pelvic pain is associated with induced adnexal or uterine pain on examination. 1
Clinical Diagnostic Approach
- The diagnosis is primarily clinical and requires a low threshold for suspicion in any woman of reproductive age presenting with pelvic or lower abdominal pain 2, 3
- Look for lower genital tract inflammation combined with pelvic organ tenderness on bimanual examination 2
- Consider milder presentations including abnormal vaginal discharge, intermenstrual bleeding, postcoital bleeding, and urinary frequency, particularly in women at risk for sexually transmitted infections 2
- Pelvic pain and fever are commonly absent in women with confirmed PID, making diagnosis challenging 2
Essential Diagnostic Testing
- Pelvic ultrasonography is necessary to rule out tubo-ovarian abscess (TOA) 1
- Obtain endocervical samples for molecular and bacteriological analysis to identify causative organisms 1
- If TOA is present, obtain samples from the abscess for culture 1
Key Pitfall
The definitive diagnosis requires laparoscopic visualization of inflamed, purulent fallopian tubes, but this is impractical in routine practice 3. Therefore, err on the side of overdiagnosis and early treatment to prevent serious reproductive sequelae including infertility, ectopic pregnancy, and chronic pelvic pain 2, 4.
Treatment Regimens
All treatment regimens must provide broad-spectrum coverage against C. trachomatis, N. gonorrhoeae, anaerobes, gram-negative rods, and streptococci. 5
Outpatient Treatment for Mild-to-Moderate PID
The recommended first-line outpatient regimen is ceftriaxone 1 g IM once, plus doxycycline 100 mg orally twice daily for 14 days, with metronidazole 500 mg orally twice daily for 14 days. 6, 1
Alternative Outpatient Regimens
- Cefoxitin 2 g IM with probenecid 1 g orally (single dose), plus doxycycline 100 mg orally twice daily for 14 days, with or without metronidazole 500 mg orally twice daily for 14 days 6
- Fluoroquinolone-based regimen: Levofloxacin 500 mg orally once daily for 14 days OR ofloxacin 400 mg orally twice daily for 14 days, PLUS metronidazole 500 mg orally twice daily for 14 days 6
Rationale for Each Component
- Ceftriaxone provides superior coverage against N. gonorrhoeae compared to cefoxitin 6
- Doxycycline targets C. trachomatis 6, 7
- Metronidazole provides essential anaerobic coverage and treats bacterial vaginosis, which is frequently associated with PID 6, 4
- Fluoroquinolones (levofloxacin/ofloxacin) are effective against both N. gonorrhoeae and C. trachomatis 6
Critical Caveat
Ceftriaxone has NO activity against C. trachomatis, so appropriate antichlamydial coverage (doxycycline or azithromycin) must always be added 7. This is a common pitfall in treatment.
Inpatient Treatment for Severe PID
Hospitalization is strongly recommended in the following situations 5:
- Diagnosis is uncertain
- Surgical emergencies (appendicitis, ectopic pregnancy) cannot be excluded
- Tubo-ovarian abscess is suspected or confirmed
- Patient is pregnant
- Patient is an adolescent (due to unpredictable compliance and severe long-term sequelae)
- Severe illness precludes outpatient management
- Patient cannot tolerate oral medications
- Failed outpatient therapy
- Clinical follow-up within 72 hours cannot be arranged
Recommended Inpatient Regimen A
Cefoxitin 2 g IV every 6 hours OR cefotetan 2 g IV every 12 hours, PLUS doxycycline 100 mg IV or orally every 12 hours 5, 6
- Continue IV therapy for at least 48 hours after clinical improvement 5
- After discharge, continue doxycycline 100 mg orally twice daily to complete 14 days total 5
Recommended Inpatient Regimen B
Clindamycin 900 mg IV every 8 hours, PLUS gentamicin loading dose 2 mg/kg IV or IM, followed by maintenance dose 1.5 mg/kg every 8 hours 5, 6
- Continue IV therapy for at least 48 hours after clinical improvement 5
- After discharge, continue doxycycline 100 mg orally twice daily for 14 days total 5
- Alternatively, clindamycin 450 mg orally four times daily for 14 days may be substituted 5
Updated Severe PID Regimen (Most Recent Evidence)
Ceftriaxone 1-2 g IV daily until clinical improvement, PLUS doxycycline 100 mg twice daily (IV or oral), PLUS metronidazole 500 mg three times daily (IV or oral) for 14 days total 1
Rationale for Inpatient Regimens
- Both cefoxitin/doxycycline and clindamycin/aminoglycoside combinations have extensive clinical experience and are highly effective in achieving clinical cure 5
- Clindamycin provides more complete anaerobic coverage than doxycycline 5
- When C. trachomatis is strongly suspected, doxycycline is the preferred post-discharge agent 5
- Aminoglycosides combined with clindamycin are highly effective for treating abscesses despite theoretical concerns about penetration 5
- Serum aminoglycoside monitoring is usually not required in healthy young women receiving short courses 5
Management of Tubo-Ovarian Abscess
Drainage of TOA is indicated if the pelvic fluid collection measures more than 3 cm 1
Evidence Quality and Comparative Effectiveness
Azithromycin vs. Doxycycline
Based on the highest quality evidence, azithromycin probably improves cure rates in mild-moderate PID compared to doxycycline (RR 1.35,95% CI 1.10 to 1.67) 8. However, the overall evidence is mixed, with some studies showing no difference 8.
Quinolones vs. Cephalosporins
There is likely little or no clinically relevant difference between quinolones and cephalosporins in cure rates for mild-moderate or severe PID 8.
Metronidazole Addition
There is probably little or no difference in cure rates whether metronidazole is added to regimens for mild-moderate PID (high-quality evidence) or severe PID (moderate-quality evidence) 8. However, metronidazole should still be considered in most cases to provide anaerobic coverage 3, particularly given the frequent association with bacterial vaginosis 6, 4.
Critical Follow-Up Requirements
Patients on outpatient therapy must demonstrate substantial clinical improvement within 72 hours, including defervescence, reduction in abdominal tenderness, and reduction in cervical motion tenderness 6.
If no improvement occurs within 72 hours 5, 6:
- Reevaluate the patient immediately
- Hospitalize for parenteral therapy
- Perform additional diagnostic testing to rule out abscess or alternative diagnoses
Parenteral therapy can be discontinued 24 hours after clinical improvement, with oral therapy continued to complete 14 days total 6.
Management of Sexual Partners
All sexual partners who had contact with the patient during the 60 days preceding symptom onset must be examined and treated 6. This is critical to prevent reinfection and address likely urethral gonococcal or chlamydial infection 6.
Partners should be treated empirically with regimens effective against both C. trachomatis and N. gonorrhoeae, regardless of the identified etiology of the patient's PID 6.
Additional Follow-Up Recommendations
- Follow-up examination within 72 hours is mandatory for outpatient therapy 6
- Follow-up is required in women with sexually transmitted infections 1
- Condom use is strongly recommended 1
- Vaginal sampling for microbiological diagnosis is recommended 3-6 months after PID, before IUD insertion, and before elective termination of pregnancy or hysterosalpingography 1
Special Populations
HIV-Infected Women
PID in immunocompromised women may be more clinically severe and more refractory to medical management 5. Consider hospitalization more liberally in HIV-infected women with PID 5.
Pregnant Women
All pregnant women with PID should be hospitalized for parenteral therapy 5.
Adolescents
Hospitalization is particularly recommended for adolescents due to unpredictable compliance and the potentially severe long-term reproductive sequelae in this age group 5.
Common Pitfalls to Avoid
- Failing to add antichlamydial coverage when using ceftriaxone alone 7
- Discharging patients before completing at least 48 hours of IV therapy and demonstrating clinical improvement 5
- Not arranging 72-hour follow-up for outpatient cases 6
- Failing to treat sexual partners 6
- Underestimating disease severity in patients with mild symptoms 2
- Not considering anaerobic coverage in most cases 3