Angie Derry knew that her Essure implants were designed to remain inside her body forever. But two years after a doctor inserted the tiny coils into her fallopian tubes to prevent pregnancy, the Rockford mother wants them removed.

Derry, 35, isn't hoping to have more children. Instead, she wonders whether getting rid of the implants will somehow alleviate the mysterious ailments that she said began after seeking permanent birth control with Essure in 2011.

At the very least, Derry wants to rule out Essure as the cause of her joint, back and pelvic pain, chronic low-grade fever, cramping, numbness and tingling, hair thinning and extreme fatigue.

"It's the only thing that makes sense," said Derry, who has undergone a barrage of medical tests over the past two years but still has no diagnosis. "My doctors are grasping at straws."

Essure, on the market since 2002, has been hailed as the next generation of permanent contraception. Unlike a tubal ligation, which requires surgery, Essure can be inserted by catheter in a doctor's office, without anesthesia or incisions. Most patients return to normal activities in one or two days.

But complaints about Essure have recently surged. The U.S. Food and Drug Administration has received nearly 1,000 "adverse event" reports related to the device, with 500 arriving in 2013. The most common issues cited are pain, hemorrhaging, headaches, menstrual irregularities, weight fluctuation, device migration and suspected nickel allergy.

Thousands of women also have joined support groups on social media to discuss debilitating side effects and baffling medical problems they link to Essure. Some women have undergone a hysterectomy or other procedure to remove coils that were never meant to be taken out of the body.

Bayer Healthcare, which purchased Essure manufacturer Conceptus in June, said in a statement that Essure has a "well-documented benefit-risk profile" and has been placed in 750,000 women worldwide. "Patient safety is of utmost importance to Bayer," the statement said, adding that the company works with the FDA to update patients and physicians when new information about efficacy or safety becomes available.

In response to patients' complaints, the FDA over the last nine months re-examined the results of the manufacturer's safety studies along with reports of problems, including testimonials from the Internet. The agency found that Essure's labeling addresses some of the issues and that no conclusive evidence connects Essure to symptoms such as extreme fatigue, depression and weight change.

"Although there is evidence of complications, as there are with all medical devices, overall results from this study did not demonstrate any new safety problems or an increased incidence of problems already known," the agency said.

By year's end, however, Bayer will revise Essure's patient brochure to state that in rare cases coils can move from the fallopian tubes into the lower abdomen, according to the FDA. The brochure also will list chronic pain as a rare side effect.

Some women's health advocates are calling for more safety studies and say women deserve more information about Essure's potential long-term risks. They also disagree with the characterization of the adverse events as rare.

"They sell Essure like a cruise, hand you a pamphlet like you're going on vacation," said Angie Firmalino, 41, who founded a Facebook group called Essure Problems in 2011, two years after undergoing the procedure. She said she experienced heavy periods, joint pain, sharp pelvic pain and other symptoms before learning that the coils had moved into her uterus and become embedded there.

Dr. James Presthus, a clinical assistant professor of obstetrics and gynecology at the University of Minnesota who has been implanting Essure for more than a decade, said he considers the device to be safe.

"Most patients have the expected outcome and do well," he said. "But for patients who have pain — and the device is placed correctly — we don't have an explanation."

Presthus said he removed Essure implants from five patients last month, including several who traveled from out of state to his office at Minnesota Gynecology and Surgery. "Something was wrong, they didn't feel comfortable, and they wanted it removed," he said.

In one case the device was found to have migrated into the uterine cavity; in another, it perforated the back of the uterus, Presthus said.

Over the last month at least five other women have called his office to ask about getting rid of the device. "It's most commonly related to pain or some discomfort," said Presthus. "But for the number of devices placed, it's a low number."

Some patients may have symptoms not because of Essure but because they stopped using oral contraceptives, noted Dr. Alexander Lin, co-medical director of Northwestern Memorial Physicians Group Division of Obstetrics and Gynecology.

Hormonal forms of birth control can mask underlying conditions such as fibroids and endometriosis that could later flare up and cause problems like heavy, painful periods and chronic pelvic pain, Lin said. After patients stop oral contraceptives, they may experience "irregular and at times heavy and prolonged menstrual bleeding," he said.