On ultrasound, an IUD appears as a bright white, T-shaped structure sitting inside the dark cavity of the uterus. The exact appearance depends on the type of IUD you have, the ultrasound technique used, and whether the device is sitting where it should be. If you’ve recently had an ultrasound to check your IUD’s position, or you’re wondering what your provider is looking for, here’s what shows up on the screen and what it means.
How a Copper IUD Appears
A copper IUD (ParaGard) is the easiest type to spot on ultrasound. The device itself is a polyethylene T-frame, but roughly 380 square millimeters of copper wire is coiled around its stem and both crossbars. That copper is highly reflective to sound waves, making the entire T-shape show up as a bright, well-defined structure against the darker uterine tissue. Radiologists rate its visibility on standard 2D ultrasound at about 5.3 out of a possible score, compared to just 3.1 for hormonal IUDs.
You’ll also notice a visual artifact trailing behind the device on the image. Copper coils produce what’s called a “ring-down artifact,” a streak of brightness extending below the IUD that helps confirm its material. The anterior and posterior surfaces of the device create two parallel bright lines known as entrance-exit reflections, essentially the sound waves bouncing off the front and back walls of the device.
How a Hormonal IUD Appears
Hormonal IUDs like Mirena, Kyleena, and Liletta are made of a polyethylene frame with a hormone reservoir along the stem. The arms contain barium sulfate, which makes the device visible on X-ray but does very little to improve its appearance on ultrasound. As a result, hormonal IUDs are significantly harder to see on a standard 2D scan.
Rather than a clear T-shape, you’ll typically see only portions of the device: a bright dot or short line at the top of the stem where the arms meet, and another bright spot at the bottom tip. The arms themselves and much of the shaft may blend into the surrounding tissue. Providers sometimes describe the hormonal IUD as appearing like a broken or incomplete line rather than a distinct T. This lower visibility is one reason your provider may recommend a specific type of ultrasound to get a better look.
2D Versus 3D Ultrasound
A standard 2D ultrasound shows the uterus in two planes: a lengthwise (sagittal) view and a cross-section (transverse) view. These are useful for confirming the IUD is inside the uterus and roughly in the right position, but they have a significant limitation. Neither view shows the uterus from the front, which is the angle that best reveals whether both arms of the T are fully spread and centered in the cavity.
3D ultrasound solves this by capturing a volume of tissue and reconstructing a coronal view, essentially a front-facing image of the uterine cavity. In this view, a correctly placed IUD appears centered in the cavity with both arms extending symmetrically toward the corners of the uterus. The vertical stem sits along the midline, with its lower tip just above the narrowing where the uterus meets the cervix. Both copper and hormonal IUDs become dramatically easier to evaluate with 3D imaging. Hormonal IUD visibility jumps from a score of 3.1 on 2D to 6.2 on 3D, nearly matching copper’s 3D score of 6.6.
If your provider suspects the IUD has shifted or if you’re having symptoms like pain or unusual bleeding, 3D ultrasound is the more reliable tool for diagnosing the problem.
What Correct Placement Looks Like
On ultrasound, a well-positioned IUD sits high in the uterine cavity, close to the fundus (the rounded top of the uterus). The vertical stem runs along the center of the cavity, and both arms open symmetrically toward the uterine walls without poking into the surrounding muscle. No part of the device should extend beyond the bright line of the endometrial lining.
Providers measure the distance between the top of the IUD and the fundal endometrium (the inner lining at the top of the uterus). Research has found that an IUD sitting more than 10 millimeters from the fundal lining is associated with a higher risk of expulsion. A low-lying IUD, one that has slipped down toward the cervix, is visible on ultrasound as a device sitting in the lower segment of the uterus rather than nestled near the top.
Signs of a Mispositioned or Embedded IUD
Sometimes an IUD doesn’t stay where it was placed. On ultrasound, malposition can take several forms, and 3D imaging is particularly good at catching them.
- Embedded IUD: Part of the device, usually one or both arms, extends past the endometrial lining and into the muscular wall of the uterus (myometrium). On the coronal 3D view, you can see the arm protruding beyond the bright endometrial echo into the darker muscle tissue.
- Displaced or rotated IUD: The device may tilt to one side, rotate, or drop into the cervical canal. Instead of a symmetric T centered in the cavity, the image shows the device at an angle or lower than expected.
- Perforated IUD: In rare cases, the device partially or fully pushes through the uterine wall. If ultrasound doesn’t show the IUD inside the uterus at all, an abdominal X-ray is the next step to check whether it has migrated outside the uterus entirely.
These findings matter because an embedded or displaced IUD can cause pelvic pain, abnormal bleeding, or reduced contraceptive effectiveness. The coronal 3D view is especially useful here because it shows the relationship of each arm to the endometrial cavity in a single image, making it easy to see exactly where the device has gone wrong.
When IUD Strings Are Missing
If you or your provider can’t feel the IUD strings during a check, ultrasound is the standard next step. Missing strings can happen for several reasons: the strings curled up into the uterus, the IUD shifted position, the device was expelled without you noticing, or in rare cases, the IUD perforated the uterine wall.
On ultrasound, if the bright signature of the IUD appears in the expected location within the uterine cavity, the strings have likely just retracted and the device is still functional. If the IUD isn’t visible in the uterus at all, an abdominal and pelvic X-ray is taken to determine whether it migrated outside the uterus. In some cases where the IUD needs to be removed and strings aren’t accessible, providers use real-time ultrasound guidance to locate and retrieve the device in the office.
IUD With an Intrauterine Pregnancy
Though uncommon, pregnancy can occur with an IUD in place. On ultrasound, both the IUD and the gestational sac are visible simultaneously. The IUD typically appears in its usual bright T-shape in the upper portion of the uterine cavity, while the gestational sac (containing the early pregnancy structures like a yolk sac) appears adjacent to it. The two structures sit side by side rather than overlapping, which helps providers assess the situation and plan next steps.