Women implanted with the controversial Essure sterilization device reported experiencing heavier periods and more pelvic or abdominal pain than patients who’d had their tubes tied, according to new data from the device-maker Bayer.

Approximately 16% of Essure patients experienced abnormal bleeding and 9.1% reported chronic pelvic or lower abdominal pain, compared to 10.2% and 4.5%, respectively, in the group that had tubal ligation. Nearly one in five patients in the Essure group required gynecologic surgery later on, far surpassing the 3% in the tubal ligation group who needed follow-up surgery. 

The analysis was part of post-market research required by the U.S. Food and Drug Administration. The study included 340 women who’d been implanted with Essure and 788 women who had traditional laparoscopic tubal sterilization. An estimated 750,000 women worldwide have been implanted with Essure, which Bayer removed from the market in 2018 amid safety concerns and lawsuits.

“Although Essure is no longer available for implantation in the U.S., the FDA remains committed to evaluating long-term safety information in women who have received the device, including data from an FDA-required postmarket surveillance study,” said Dr. Terri L. Cornelison, director of the FDA’s Health of Women Program in the Center for Devices and Radiological Health, in a statement.

The FDA required Bayer to conduct a postmarket surveillance study on Essure beginning in 2016 after adverse-event reports of pain, heavy periods, menstrual irregularities, depression and anxiety related to the device. 

In a statement to MedPage Today, Bayer said it continues to stand behind Essure. “While all birth control products and procedures have risks, the totality of scientific evidence on Essure demonstrates that its safety profile is consistent with the risks disclosed since its 2002 approval and is comparable to other female permanent birth control options.”

Diana Zuckerman, president of the National Center for Health Research, has criticized the original clinical data supporting the FDA’s approval of Essure, calling it inadequate. 

Over Essure’s 17-year term on the market, the FDA received 47,856 adverse event reports about the device. As of late July, 32,000 U.S. women had filed lawsuits against Bayer related to Essure.