Most Common Infection Associated with Intrauterine Devices
The most common infection associated with IUDs is pelvic inflammatory disease (PID), which is a polymicrobial upper genital tract infection involving organisms from the lower genital tract that ascend during the insertion process. 1, 2
Pathophysiology and Timing
PID risk is highest immediately after IUD insertion, with the greatest risk occurring within the first 20 days post-insertion. 3, 4
- The risk of PID is more than six times higher during the first 20 days after insertion (9.7 per 1000 woman-years) compared to later time periods (1.4 per 1000 woman-years). 3
- IUD insertion mechanically disrupts the cervical barrier, facilitating upward spread of vaginal and cervical bacteria to the endometrium and fallopian tubes through direct canalicular spread. 2
- After the initial 20-day period, PID risk remains low and constant for up to eight years of follow-up. 3
Causative Organisms
PID associated with IUDs is polymicrobial, involving the same organisms as non-IUD-related PID. 2
The microbiology includes:
- Sexually transmitted pathogens: Chlamydia trachomatis and Neisseria gonorrhoeae 2
- Anaerobes: Bacteroides, Peptostreptococcus, and Peptococcus species 2
- Facultative bacteria: Gardnerella vaginalis, Streptococcus species, E. coli, and Haemophilus influenzae 2
Critical Clinical Distinction: Actinomyces
While Actinomyces species have been historically associated with IUDs, they are very uncommon and typically occur only in two specific settings: 1
- When a patient has an infection at the time of IUD insertion 1
- When the IUD is left in place past the recommended removal time (typically 5 years) 1
Actinomyces is NOT the most common infection with IUDs—this is a common misconception. 1
Risk Factors and Prevention
The absolute risk of PID following IUD insertion is low in women without pre-existing STIs, but significantly elevated in women with cervical infection at insertion. 2
Key prevention strategies:
- Screen all women by history and physical examination for STI risk prior to insertion. 5
- Women at increased risk should be tested for chlamydia and gonorrhea prior to or at insertion, but insertion need not be delayed for results. 5
- Women with current purulent cervicitis, chlamydial infection, or gonorrhea should not have an IUD inserted until infection is treated. 2
- Routine prophylactic antibiotics are not recommended prior to IUD insertion. 5
Management of PID in IUD Users
When PID develops in an IUD user, it is diagnosed and managed as standard PID with appropriate antibiotics. 2
- For mild to moderate PID, the IUD does not need to be removed during treatment unless the patient requests removal or there is no clinical improvement after 72 hours of appropriate antibiotics. 5
- For severe PID, consider removing the IUD after starting appropriate antibiotic therapy. 5
- Clinical outcomes do not differ whether the IUD is removed or left in place during treatment. 2