The intrauterine device (IUD) is one of the most effective forms of long-acting reversible contraception (LARC). Although generally safe, a rare complication called uterine perforation can occur when the IUD punctures the wall of the uterus. Large-scale medical studies confirm this is an uncommon event. Understanding the risk factors helps ensure proper counseling and timely management.
Defining Uterine Perforation
IUD perforation describes a breach in the muscular uterine wall (myometrium) caused by the device. This damage is classified based on the extent of the puncture. A partial perforation, or embedment, occurs when the IUD penetrates the muscle layer but remains partially within the uterine wall. A complete perforation happens when the IUD passes entirely through the uterine wall and moves into the abdominal or pelvic cavity. Most perforations are primary events, meaning the puncture occurred during insertion. Secondary or delayed perforation, where the device gradually erodes through the wall, is extremely rare.
The True Incidence Rate of Perforation
IUD perforation is a rare event, with the overall rate typically cited between 1 and 2 per 1,000 insertions. The European Active Surveillance Study on IUDs (EURAS-IUD) reported an incidence of 1.1 to 1.4 perforations per 1,000 insertions, with similar rates for hormonal and copper IUDs.
The U.S. APEX-IUD study, which followed over 326,000 women, determined the 5-year cumulative incidence of perforation in the non-postpartum group was 0.29%. Perforations are most often diagnosed within the first year after insertion, reflecting that the puncture usually occurs at the time of placement.
Key Factors Influencing Risk
Although the overall risk is low, certain circumstances during insertion can elevate the likelihood of perforation. The most significant factor is the timing of insertion relative to a recent delivery. Insertion between four days and six weeks postpartum carries the highest risk, increasing the perforation rate by nearly seven times compared to non-postpartum insertion. This heightened risk occurs because the uterus is softer and more pliable following childbirth, making the muscular wall easier to puncture.
Breastfeeding at the time of insertion is also associated with increased risk. This may be related to the hypoestrogenic state and the effects of oxytocin on uterine contractility. The risk associated with breastfeeding is independent of postpartum timing, but combining both factors raises the risk further.
Provider Experience
The experience level of the healthcare provider performing the insertion is another contributing factor. Providers who perform fewer IUD insertions annually may have a slightly higher perforation rate than those who are more experienced. Provider skill plays a role in the precise technique used to navigate the device. Less common factors include anatomical variations, such as uterine anomalies or a fixed retroverted uterus, which can complicate the procedure.
Recognizing and Addressing Perforation
Signs of IUD perforation are often vague or absent, as many cases are asymptomatic. However, certain symptoms should prompt immediate medical evaluation. The most common indication is the inability to feel the IUD strings, which normally hang through the cervix. Patients may also experience persistent or severe pelvic pain, worse than normal cramping, or abnormal bleeding that continues well beyond the initial insertion period.
Diagnosis
If perforation is suspected, a healthcare provider first performs a physical examination to check for the strings. The next diagnostic step is usually a transvaginal ultrasound, which confirms the IUD’s location or reveals partial embedment. If the ultrasound fails to locate the device, an X-ray or CT scan of the abdomen and pelvis is used to determine if the IUD has migrated entirely outside the uterus.
Removal
Once confirmed, the IUD is generally recommended for removal to prevent complications like adhesion formation or damage to adjacent organs, such as the bowel. Removal of a completely perforated IUD typically requires laparoscopic surgery, a minimally invasive procedure. If the device is deeply embedded in the myometrium, it may sometimes be removed hysteroscopically, using a camera inserted through the cervix.