What should I do if my Mirena (levonorgestrel-releasing intrauterine device) string is lost?

Management of Lost Mirena Strings

If your Mirena strings are not visible, you need an ultrasound to locate the device—it may still be properly positioned in the uterus, expelled without your knowledge, or rarely, perforated through the uterine wall. 1

Immediate Assessment

• Perform or refer for transvaginal ultrasound to determine the IUD location, as this is the critical first step in management 1, 2
• The device could be in one of three locations: properly positioned in the uterus (most common), expelled, or perforated through the uterine wall 3, 4
• In one large study, 69% of missing string cases had the IUD still in the uterus, 17% had unnoticed expulsions, and 9% had uterine perforation 4

Management Based on Ultrasound Findings

If IUD is Properly Positioned and You Are Asymptomatic

• The device can remain in place and continue to provide contraception 1
• No routine follow-up visit is required, though you should return at any time to discuss concerns 5
• Consider checking for IUD strings at other routine visits 5

If IUD is Malpositioned (Low-Lying, Extending into Cervix, or Embedded)

• Remove the IUD as soon as possible, especially if you have persistent pelvic pain 6, 1
• Removal can be performed without requiring an updated ultrasound if previous imaging confirmed malposition and you have persistent symptoms 6, 1
• If strings are visible or can be safely retrieved, removal involves gently pulling on the strings 6

If IUD Has Perforated the Uterus

• The device must be removed as soon as possible 1
• Uterine perforation occurs in approximately 1/350 to 1/2,500 insertions and is more common among women with "lost" IUDs 7
• If you present with pelvic pain and a history of a lost IUD, abdominal and pelvic X-rays should be ordered 7

When Strings Cannot Be Retrieved

• Refer for ultrasound-guided removal if strings are not visible and the IUD cannot be safely retrieved 6, 1
• Most patients with missing strings can be managed with relatively simple office techniques to locate and remove the device 4
• Only trained medical professionals should attempt removal beyond simple traction on visible threads 7

Post-Management Care

• Return promptly if you develop heavy bleeding, cramping, pain, abnormal vaginal discharge, or fever 6, 1
• Discuss alternative contraceptive methods if the IUD is removed 1
• If signs of infection are present, appropriate antibiotic treatment should be initiated 6
• Schedule follow-up to ensure symptom resolution and discuss future contraceptive plans 1

Important Caveats

• Do not assume the IUD was expelled—investigation is necessary in every case of missing strings 3
• The strings may have simply retracted into the uterus, which is a benign finding if the device is properly positioned 4, 2
• If you are pregnant with a lost IUD, ultrasound-guided extraction should be considered, as it has a high success rate (77% live birth rate) with moderate miscarriage risk (22%) 8