Can You See a Mirena IUD on an X-ray?
Yes, the Mirena IUD is visible on plain X-ray imaging because it contains a radiopaque barium sulfate component in its frame that allows radiographic visualization.
Radiographic Visibility of Different IUD Types
The visibility of intrauterine devices on X-ray depends on their composition and design:
Copper-containing IUDs (such as the Copper T380A) are highly radiopaque and easily visualized on plain radiographs due to their metallic copper content 1, 2.
The Mirena (levonorgestrel-releasing) IUD contains barium sulfate mixed into its polyethylene frame, making it radiopaque and visible on X-ray, though it may appear less dense than copper IUDs 1.
Older IUD models like the Lippes Loop and Saf-T-Coil have pathognomonic (characteristic) appearances on X-ray that allow identification of the specific device type 1.
Clinical Utility of X-ray for IUD Localization
Plain radiography serves an important role when ultrasound cannot locate an IUD:
When an IUD is known to be present but not visualized on ultrasound, plain radiography is helpful in assessing the device location and determining whether it remains intrauterine or has perforated into the peritoneal cavity 1, 3.
X-ray with a uterine sound in place is a simple, reliable technique for diagnosing the location of IUDs with missing strings, with an accuracy rate of approximately 95% 4.
Abdominal overview X-ray is relatively inexpensive and non-invasive, making it an appropriate next step when strings are not visible and ultrasound shows an empty uterine cavity 3.
Diagnostic Algorithm for Missing IUD Strings
When IUD strings are not visible at follow-up:
First-line imaging: Transvaginal ultrasound to assess whether the device is in the uterine cavity, has been expelled, or has perforated 5, 1, 6.
If ultrasound is inconclusive or shows an empty cavity: Obtain a plain abdominal/pelvic X-ray to locate the device 5, 3.
If X-ray shows the device outside the uterus: Laparoscopic removal is typically required 3.
Important Clinical Considerations
Missing strings occur in 5-25% of IUD insertions, but ultrasound confirms the device is in situ in approximately 98-99% of these cases 6.
Uterine perforation is uncommon (occurring in approximately 0.7% of cases with missing strings) but must be considered when strings are not visible 6.
X-ray can demonstrate IUD position changes during pregnancy, including displacement into the cervix or perforation into the pelvic cavity 7.
CT imaging also readily demonstrates IUDs and can identify malposition, embedment, or perforation when performed for other indications 2.
MRI Considerations
Copper IUDs are MR conditional and can safely undergo 3.0 Tesla MRI using low specific absorption rate (SAR) settings, with zero displacement observed in a prospective study of 70 patients 8.
The Mirena IUD is also considered MR conditional, though the barium sulfate component may create artifact on MRI sequences 1.