What is the next step in managing a 6-year Mirena (levonorgestrel-releasing intrauterine system) user with new onset bleeding after previous amenorrhea and lower back pain radiating to her legs?

Immediate Evaluation for IUD Displacement and Serious Pathology

This patient requires urgent evaluation for IUD displacement, pregnancy, and serious gynecologic pathology—the combination of new-onset bleeding after 6 years of amenorrhea plus radiating lower back pain is highly concerning and demands immediate investigation before attributing symptoms to benign causes. 1, 2, 3

Critical First Steps

The CDC explicitly warns against attributing new bleeding to other factors without first investigating IUD-related and gynecologic causes. 3 Your immediate workup must include:

• Pregnancy test - This is mandatory as the first step, regardless of amenorrhea history, as the Mirena remains effective but not 100% protective at 6 years 1, 3
• Pelvic examination - Check for visible IUD strings to assess for displacement, which commonly causes abnormal bleeding 1, 2, 3
• Pelvic ultrasound - If strings are not visible or if pain persists, ultrasound is essential to locate the IUD and evaluate for displacement, perforation, or new pathologic conditions 1, 3

Why This Presentation Is Concerning

The radiating lower back pain is the red flag here. While new-onset bleeding alone after prolonged amenorrhea warrants investigation, the addition of back pain radiating to the legs raises concern for:

• IUD perforation or migration - Can cause pelvic/back pain and bleeding 1, 2
• Pelvic inflammatory disease - Can present with pain and bleeding 2, 3
• Ectopic pregnancy - The Mirena Extension Trial documented an ectopic pregnancy in year 7 of use 4
• New uterine pathology - Fibroids, polyps, or endometrial conditions that developed during the 6 years of use 1, 2, 3

Systematic Evaluation Algorithm

If IUD strings are visible and properly positioned:

1. Screen for sexually transmitted infections (gonorrhea, chlamydia) - Common cause of new bleeding in IUD users 1, 2, 3
2. Pelvic ultrasound - Evaluate for polyps, fibroids, endometrial pathology, or early pregnancy 1, 3
3. Consider endometrial assessment if ultrasound shows thickening or abnormality 5

If IUD strings are not visible:

1. Immediate pelvic ultrasound to locate the device 3
2. If IUD has perforated or migrated, refer for removal (may require hysteroscopy or laparoscopy) 1

If infection is identified:

• Treat PID according to CDC STD Treatment Guidelines 5
• The IUD does not need immediate removal if the patient wants continued contraception 5
• Reassess in 24-48 hours; if no clinical improvement, continue antibiotics and consider IUD removal 5

Important Context About Mirena at 6 Years

The Mirena is FDA-approved for 5 years but data support efficacy up to 7-8 years. 5, 4 However, new-onset bleeding after 6 years of stable amenorrhea is NOT a normal "wearing off" pattern and requires investigation. 3 The Mirena Extension Trial showed that among women continuing use through 8 years, bleeding patterns remained favorable with approximately 50% maintaining amenorrhea. 4 New bleeding represents a change that demands evaluation, not reassurance.

Critical Pitfalls to Avoid

• Do not remove the IUD without investigating underlying causes first 3
• Do not assume the device is simply "wearing off" when pathology is more likely 3
• Do not dismiss the back pain as unrelated - it may indicate displacement, perforation, or infection 1, 2
• Do not provide false reassurance that bleeding irregularities are "normal" without ruling out serious causes 5, 1

If No Pathology Is Found

Only after excluding displacement, pregnancy, infection, and structural pathology should you consider this benign irregular bleeding. 5, 1 At that point:

• Provide reassurance that bleeding irregularities with LNG-IUDs are generally not harmful 5, 1, 2
• If bleeding persists and is unacceptable to the patient, counsel on alternative contraceptive methods 5, 1
• Consider NSAIDs for symptomatic relief during bleeding days, though evidence for LNG-IUD users is limited 5

Regarding the Back Pain

The radiating lower back pain must be evaluated in conjunction with the gynecologic workup. If pelvic pathology is excluded and pain persists, consider musculoskeletal or neurologic evaluation. However, do not pursue alternative diagnoses until IUD-related complications are definitively ruled out. 1, 2, 3