Intrauterine devices (IUDs) are a highly effective, long-acting form of reversible contraception. These small, T-shaped devices must be positioned correctly at the top of the uterus, known as the fundus, to maintain high efficacy. If the device shifts, its contraceptive protection can be reduced, potentially causing discomfort or complications. Imaging is often required to confirm the precise location of the device.
Selecting the Imaging Method
The primary and most frequently used technique for checking IUD placement is Transvaginal Ultrasound (TVUS). This method involves inserting a specialized, thin ultrasound probe directly into the vagina. The close proximity of the probe to the uterus provides superior image resolution, making it the preferred method for visualizing the small IUD.
The IUD itself appears on the ultrasound screen as a highly echogenic, or bright, T-shaped structure within the darker outline of the uterine lining. The specific appearance can vary slightly; for instance, copper IUDs often show the entire T-shape brightly, while hormonal IUDs may only show the stem as an echogenic line with some acoustic shadowing. The arms, which anchor the device, should be fully deployed and extending laterally near the uterine fundus.
While TVUS is the standard, Transabdominal Ultrasound may be used, involving scanning over the lower abdomen for a broader pelvic view. This method offers less detailed resolution of the IUD’s position compared to TVUS. If the IUD is not seen within the uterus on ultrasound, a plain abdominal X-ray may be ordered. X-rays help locate devices that may have perforated the uterine wall and migrated, as all IUDs contain radiopaque material.
Three-Dimensional (3D) Ultrasound is increasingly utilized because it allows the clinician to view the uterus and IUD in the coronal plane. This unique view is helpful for clearly visualizing both arms of the T-shaped device. It can also detect subtle issues, such as one or both arms being embedded into the uterine muscle wall. The superior visualization provided by 3D imaging improves the accuracy of detecting malpositioned IUDs compared to standard 2D ultrasound.
When and Why Placement Checks Are Performed
An IUD placement check is often performed as a routine follow-up approximately four to six weeks after the initial insertion. This allows the healthcare provider to confirm that the device has settled correctly into the uterine fundus and to address any initial side effects. While not always mandatory for asymptomatic patients, a routine check offers reassurance.
The most common reason for a placement check is when the user or provider is unable to feel the IUD’s retrieval strings during a self-check or pelvic exam. The strings are meant to hang a short distance through the cervix into the vagina. If they cannot be located, it raises concern that the IUD may have shifted, requiring imaging to determine if the strings have retracted or if the entire device has moved.
Checks are also prompted by new or persistent symptoms suggesting a problem with the device’s location. These symptom-driven checks include new or worsening pelvic pain, severe cramping, or abnormal bleeding. Ultrasound is used in these cases to rule out partial expulsion, displacement, or embedment, which are common forms of IUD misplacement.
Understanding IUD Positioning and Follow-Up Care
A correctly positioned IUD is situated high within the uterine cavity, with the top of the T-frame resting near the fundus. The arms of the device should be fully extended laterally, often appearing to gently touch the sides of the uterine wall. This placement is necessary for the IUD to exert its full contraceptive effect.
Misplacement can manifest in several ways, which ultrasound identifies. Displacement occurs when the IUD has moved down toward the lower uterine segment or into the cervical canal, significantly increasing the risk of expulsion and reducing contraceptive efficacy. Embedment is diagnosed when a portion of the IUD, often an arm, has penetrated and fixed itself into the uterine muscle wall, but has not fully passed through it.
The most severe form of misplacement is perforation, where the IUD has passed completely through the uterine wall and into the surrounding pelvic or abdominal cavity. If the ultrasound confirms the IUD is in the correct fundal position, the patient can continue using the device. If the device is identified as displaced or embedded, the standard procedure is removal, often using specialized instruments or hysteroscopy for embedded devices. Following removal, the patient receives counseling on choosing a new contraceptive method, which may include immediate reinsertion.