LNG-IUD may have systemic effects

A small study presented at RSNA 2021 has suggested that the use of levonorgestrel-releasing intrauterine contraceptive devices (LNG-IUDs) may affect background parenchymal enhancement (BPE).

“Use of an IUD leads to hormonal stimulation of the breast that is detectable by [magnetic resonance imaging (MRI)],” said study author Dr Luisa Huck from the Department of Diagnostic and Interventional Radiology at RWTH Aachen University, Aachen, Germany.

“The results suggest that IUDs do not have a purely local effect on the uterus – but affect the entire body,” she noted.

Using the Aachen University Hospital database, Huck and co-authors identified 48 premenopausal women (mean age 45 years) with no personal history of breast cancer or hormone or antihormone intake. To be included, the women needed to have undergone ≥2 screening dynamic contrast-enhanced MRI (DCE-MRI) tests between January 2014 and June 2020, once with and without an IUD, carried out after a ≥4-week period following IUD placement or removal.

Half the women underwent the first breast MRI before IUD placement and the second MRI following placement, while the other half underwent the first MRI with an IUD in place and the second MRI after IUD removal.

This was done to prevent confounding due to age-related effects on BPE, noted the authors. The median time between the two assessments was 27 months.

There was a significant association between the presence or absence of IUD and the degree of BPE, as per change in American College of Radiology (ACR) category (p<0.001). [RSNA 2021, session BR01-B5]

In 48 percent of the women, ACR category was higher in those with vs without an IUD, while in 2 percent, ACR category was lower with vs without an IUD.

In the remaining 50 percent of women, presence or absence of IUD did not affect ACR category.

“It has been claimed that IUDs have a purely local effect on the uterus,” said Huck. “Our study results suggest that this is not true.”

“BPE in DCE-MRI has been established as a sensitive marker of hormonal stimulation of the breast,” noted Huck and co-authors.

“By comparing the level of contrast enhancement in the same women with and without the IUD in place, a change in systemic hormone levels due to the IUD could be traced,” Huck said. “The increased enhancement also has implications for the diagnostic accuracy of breast MRI in women using hormonal IUDs.”

Regardless of the findings, Huck provided assurance on the safety of IUDs and suggested that women pay attention should symptoms crop up.

“IUDs appear to be a very safe means of contraception and are generally well tolerated. However, if women with an IUD in place experience unexplainable side effects, they should talk to their doctor and consider using other types of contraception.