Risk factors for IUD expulsion

Heavy menstrual bleeding is the No. 1 risk factor for intrauterine device (IUD) expulsion, according to an analysis of a US cohort study of 3 integrated health care systems published in the journal Obstetrics & Gynecology.

Women who were overweight, younger age, or parity of at least 4 were also at high risk of expulsion.

The analyses of the Association of Perforation and Expulsion of IntraUterine Devices (APEX-IUD) study assessed health records from Kaiser Permanente Northern California, Southern California, and Washington, plus from the health care information exchange Regenstrief Institute in Indianapolis, Indiana.

Of 228,834 individuals aged 50 years or younger with IUD insertion from 2001 to 2018 and no delivery in the previous 52 weeks, 80.7% had a levonorgestrel-releasing intrauterine system (LNG-IUD), 18.0% a copper IDU, and 1.3% unknown.

Any prior heavy menstrual bleeding diagnosis was more common among LNG-IUD users than copper IUD users: 21.2% vs 4.8%, respectively. Both complete expulsions and partial expulsions were included. The maximum follow-up time was 10 years, with an average follow-up of 2.0 years.

Overall, there were 6,762 expulsions, for a crude incidence rate of 14.9 per 1000 person-years (95% confidence interval [CI]: 14.6 to 15.3).

Diagnosis of heavy menstrual bleeding, especially a diagnosis in both recent and past periods, was the strongest indicator for IUD expulsion.

Categories with the highest risk of IUD expulsion within each risk factor included individuals diagnosed as overweight, obese, or morbidly obese; younger age groups, particularly those aged 24 years or younger; and those with a parity of 4 or more.

The lowest incidence and risk of IUD expulsion were among Non-Hispanic White women, whereas Asian or Pacific Islanders had the highest risk, after adjusting for age, race and ethnicity, parity, body mass index (BMI), heavy menstrual bleeding, dysmenorrhea, and potential confounders.

However, dysmenorrhea was not independently linked to expulsion risk when adjusted for heavy menstrual bleeding.

“Most risk factors for expulsion identified in this study appear consistent with known physiologic factors that affect uterine anatomy and physiology,” wrote the authors.

A potential mechanism for higher expulsion risk is the connection between increased inflammation and greater adiposity.

It may also be more challenging to place an IUD at the fundus, due to body habitus in obese women, thus perhaps leading to a higher risk of expulsion.

The analysis supports the finding of previous studies that show the risk of expulsion is a stronger predictor among younger people using a cooper IUD than a LNG-IUD.

The authors speculated that younger nulliparous individuals have a higher risk of IUD expulsion because of a smaller uterine cavity and more difficult IUD placement due to nulliparity.

Race and ethnicity outcomes should be interpreted with caution, according to the authors, because these factors are social constructs not rooted in biological differences. Racial and ethnic differences in diagnosed risk factors for expulsion, along with cultural constructs, may explain the greater expulsion risk differences by race and ethnicity in the LNG-IUD group.

The increased risk of IUD expulsion in women of color should be further investigated, the authors noted.

Risk factors may also differ between partial and complete expulsions. In addition, some malpositioned IUDs may have been removed due to individual choice and not because of IUD positioning.

“Intrauterine devices are an effective long-term contraceptive; expulsion is uncommon, but patients should be counseled accordingly,” wrote the authors.

Reference:

1. Anthony MS, Zhou X, Schoendorf J, et al. Demographic, reproductive, and medical risk factors for intrauterine device expulsion. Obstet Gynecol: Published online November 3, 2022. doi:10.1097/AOG.0000000000005000