Mirena IUD and Fever
Fever after Mirena IUD insertion is not a normal side effect and should raise immediate concern for infection, particularly pelvic inflammatory disease (PID) or, rarely, toxic shock syndrome, which requires urgent evaluation.
Risk of Infection After IUD Insertion
The risk of pelvic infection with IUDs, including Mirena, is limited to the first 21 days after insertion, after which IUDs do not increase rates of sexually transmitted infections or PID above baseline 1. The mechanism appears to be bacterial contamination of the endometrial cavity during the insertion procedure itself, rather than the device or string 2.
- The overall infection risk is low (approximately 5.9% or less in most studies), with the majority of cases occurring within the first 3 months, particularly in the first few weeks after insertion 1, 3.
- Fever developing after IUD insertion warrants immediate evaluation for PID or other pelvic infections 4.
When to Suspect Serious Infection
Toxic shock syndrome, though rare, is a potentially catastrophic complication that can present with high fever, myalgias, and abdominal pain within days of IUD insertion 4. This case report documented group A Streptococcus infection leading to streptococcal toxic shock syndrome requiring ICU admission just 2 days after levonorgestrel IUD insertion 4.
Key Clinical Features to Assess:
- Timing: Fever within the first 21 days post-insertion is most concerning 1
- Associated symptoms: Abdominal pain, myalgias, signs of sepsis 4
- Severity: High fever with systemic symptoms requires urgent evaluation 4
Management Approach
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 antibiotic therapy 5. Studies demonstrate that both STIs and PID can be treated with the IUD in place, provided the patient improves with treatment 1.
- In severe PID or toxic shock syndrome, consideration should be given to removing the IUD after appropriate antibiotic treatment has been started 5.
- Immediate evaluation is mandatory for any patient presenting with fever and systemic symptoms after IUD insertion 4.
Contraindications and Risk Factors
Absolute contraindications to IUD placement include: current purulent cervicitis, active gonorrhea or chlamydia infection, current PID, and other active pelvic infections 1. However, past PID is not a contraindication 1.
- Women at very high risk for STIs should be screened for gonorrhea and chlamydia, which can be performed on the day of insertion, with treatment provided subsequently without IUD removal if the patient is asymptomatic 1.
- HIV infection and immunosuppression are not contraindications to IUD use 1.
Bottom Line
Fever is not an expected side effect of Mirena IUD and requires prompt medical evaluation to rule out PID or toxic shock syndrome, particularly if occurring within the first 21 days after insertion 1, 4. While infection risk is low overall, the consequences of missing serious infection can be severe 4, 5.