What are other serious complications to consider in a 6-year-old female Mirena (levonorgestrel) IUD user presenting with new-onset bleeding and radiating lower back pain?

Other Serious Complications in a 6-Year-Old Female Mirena User with New-Onset Bleeding and Radiating Lower Back Pain

In a 6-year-old female with a Mirena IUD presenting with new bleeding and radiating lower back pain, the most critical serious complications to exclude are uterine perforation, ectopic pregnancy, pelvic inflammatory disease, and IUD displacement—all of which can cause significant morbidity if not promptly identified and managed. 1

Critical Life-Threatening Complications

Uterine Perforation

• Uterine perforation is a rare but serious complication that can present with pelvic or lower back pain and abnormal bleeding, occurring in approximately 0.5-1.2% of IUD users 2, 3
• The IUD can migrate into the peritoneal cavity, Retzius space, or adjacent organs, requiring surgical removal via laparoscopy 2
• Radiating lower back pain is a concerning feature that may indicate extrauterine IUD location or peritoneal irritation 2
• Diagnosis requires pelvic ultrasound to confirm IUD position; if strings are not visible and device cannot be visualized in the uterus, CT imaging may be necessary 4, 2

Ectopic Pregnancy

• Although the Mirena IUD has a failure rate of less than 1%, when pregnancy does occur, there is a disproportionately higher risk of ectopic pregnancy 3, 5
• The Pearl Index for ectopic pregnancy during years 6-8 of Mirena use is 0.14 per 100 woman-years 5
• New-onset bleeding with pelvic/back pain mandates pregnancy testing, as ectopic pregnancy can present with these symptoms and lead to life-threatening hemorrhage if ruptured 4, 5
• Any positive pregnancy test in an IUD user requires immediate evaluation for ectopic pregnancy 4

Pelvic Inflammatory Disease (PID)

• PID risk is elevated primarily in the first 21 days after IUD insertion but can occur at any time during use, with an annual incidence of 0.2-0.5% in copper IUD users and similar rates for levonorgestrel IUDs 1, 3
• Lower back pain can represent ascending infection or tubo-ovarian abscess formation 6
• The IUD does not need immediate removal if PID is diagnosed; treatment with antibiotics should be initiated and the patient reassessed in 24-48 hours 1
• If no clinical improvement occurs after 24-48 hours of antibiotic therapy, IUD removal should be considered 1

Serious Structural Complications

IUD Displacement or Expulsion

• Expulsion rates for levonorgestrel IUDs range from 0-1.2% per year, with displacement potentially causing abnormal bleeding and pain 3, 5
• Partial expulsion can cause endometrial trauma and irregular bleeding while also compromising contraceptive efficacy 4
• Confirm device position by checking for visible strings; if strings are not visible, obtain pelvic ultrasound to evaluate for displacement or expulsion 4
• Displaced IUDs can cause localized endometrial ulceration and inflammation, contributing to pain symptoms 6

Other Pathologic Conditions to Exclude

New Uterine Pathology

• The 2024 CDC guidelines emphasize evaluating for new pathologic uterine conditions such as polyps or fibroids when IUD users present with heavy or prolonged bleeding 1
• These conditions can develop during IUD use and may present with bleeding and pelvic pain 1
• Pelvic ultrasound is indicated to assess for structural abnormalities if bleeding is heavy, prolonged, or concerning 4

Sexually Transmitted Infections

• STIs should be considered in any IUD user with new-onset pelvic pain and bleeding, as they can progress to PID if untreated 1
• STI screening should be performed as part of the evaluation, particularly in sexually active adolescents 1
• Treatment of STIs can be provided without IUD removal in most cases 1

Clinical Approach Algorithm

Step 1: Immediate Assessment

• Obtain urine pregnancy test to rule out pregnancy (including ectopic) 4
• Perform pelvic examination to check for visible IUD strings and assess for cervical motion tenderness, adnexal tenderness, or masses 4

Step 2: If Strings Not Visible or Examination Concerning

• Obtain pelvic ultrasound to confirm IUD position and evaluate for perforation, displacement, or other pathology 4, 2
• If IUD not visualized in uterus on ultrasound, obtain abdominal X-ray or CT to locate device 2

Step 3: If Signs of Infection

• Obtain STI screening (gonorrhea, chlamydia) and consider PID diagnosis 1
• Initiate antibiotic therapy per CDC STD Treatment Guidelines 1
• Reassess in 24-48 hours; if no improvement, consider IUD removal 1

Step 4: If Pregnancy Test Positive

• Immediate evaluation for ectopic pregnancy with transvaginal ultrasound and serial beta-hCG levels 5
• Remove IUD if intrauterine pregnancy confirmed; urgent gynecology consultation if ectopic pregnancy suspected 5

Critical Pitfalls to Avoid

• Do not assume bleeding irregularities are normal without excluding serious complications, especially when accompanied by pain 1
• Do not delay imaging if strings are not visible, as this may indicate perforation or expulsion requiring intervention 4, 2
• Do not automatically remove the IUD for PID; treatment can be initiated with the device in place and removal considered only if no clinical improvement after 24-48 hours 1
• Do not miss ectopic pregnancy; always obtain pregnancy testing in IUD users with new bleeding and pain, as the consequences of missed diagnosis are catastrophic 5