An intrauterine device (IUD) is a small, T-shaped form of long-acting reversible contraception placed inside the uterus by a healthcare provider. The device works by releasing hormones or copper to prevent pregnancy. While IUDs are highly effective, a known complication is expulsion, which occurs when the device partially or completely slides out of the uterine cavity. This event is uncommon but results in a loss of contraceptive effectiveness and requires medical attention.
Identifying Individual Risk Factors
Certain pre-existing conditions and personal characteristics increase the likelihood of IUD expulsion. The strongest risk factor is a history of heavy menstrual bleeding, also known as menorrhagia. Individuals with chronic heavy bleeding face a substantially higher risk, suggesting that the physiological environment of a uterus prone to heavy flow plays a role in dislodging the device.
Other factors contributing to the risk profile relate to uterine size and activity. Individuals younger than 25 years old at insertion have higher expulsion rates. Similarly, those who have given birth four or more times (high parity) also face an elevated risk. A history of a previous IUD expulsion is a major predictor, significantly increasing the chance of recurrence with a replacement device.
Uterine structural anomalies, such as fibroids or a bicornuate uterus, can distort the cavity, making a secure fit challenging. Additionally, a higher body mass index (BMI), particularly in the overweight or obese ranges, has been associated with increased expulsion incidence. These factors influence the uterus’s ability to retain the device.
Immediate Causes Related to Uterine Activity and Insertion Timing
The direct forces causing IUD expulsion are primarily related to muscular activity within the uterus. Uterine contractions, especially the strong, rhythmic spasms during menstruation, can physically push the device downward toward the cervix. These contractions are the most common mechanical trigger for expulsion, which is why many expulsions are noticed during a menstrual period.
The timing of IUD insertion relative to a recent pregnancy significantly affects expulsion risk. When an IUD is placed immediately after childbirth or a second-trimester abortion, the uterus is enlarged and rapidly shrinking back to its non-pregnant size (involution). Expulsion rates for immediate postpartum insertion (within ten minutes of placental delivery) can be 10% to 13%, compared to under 2% for insertions done four or more weeks later.
The risk is heightened further if insertion occurs after a vaginal delivery rather than a cesarean section. If the IUD is not placed correctly at the highest point of the uterine cavity (the fundus), it is inherently unstable and prone to displacement. An IUD seated too low from the start is subject to greater expulsion forces and is considered improperly placed.
The type of IUD may also play a role; some studies suggest the hormonal IUD has a higher expulsion risk than the copper IUD following a postpartum vaginal delivery. Another mechanical issue is a size mismatch, where a standard IUD may be too large for a smaller uterine cavity, such as those found in some nulliparous individuals. This discrepancy can lead to irritation and increased contractile forces attempting to expel the device.
Signs of Expulsion and Necessary Action Steps
Signs of IUD expulsion vary, and the event is sometimes not immediately noticed. A common indicator is a change in the length of the IUD’s retrieval strings, which hang into the upper vagina. The strings may feel significantly longer, indicating partial descent, or they may be completely absent, suggesting full expulsion or migration higher into the uterus.
Physical symptoms often include severe or unusual cramping and pelvic pain atypical of a menstrual period. An individual may also experience abnormal bleeding, such as unexpected spotting or a sudden return to heavy menstrual flow, especially if they have a hormonal IUD that previously reduced bleeding. In some cases, the hard plastic tip of the IUD may be felt protruding from the cervix.
If displacement or expulsion is noticed, the individual must immediately use a reliable backup method of contraception, such as condoms. The IUD is no longer effective once it has moved from its correct position. It is important not to attempt to push the device back into place or remove it, as this can cause injury.
Contacting a healthcare provider right away is the required next step for a definitive diagnosis. The provider will perform a physical exam and often an ultrasound to confirm the IUD’s location. If expulsion is confirmed, the provider will discuss options for replacement or alternative contraceptive methods. A new IUD may be inserted, though the risk of a repeat expulsion remains.