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Women who underwent an ostensibly noninvasive sterilization technique involving the implantable Essure insert had 10 times the risk of repeat operations compared with those undergoing tubal ligation, on Tuesday.

But rates of unintended pregnancies were no higher among women treated with Essure than those having the conventional surgical sterilization, the report said.

Researchers at Weill Cornell Medicine in New York City compared the safety and efficacy of two procedures in a population-based study: noninvasive sterilization using the Essure device versus laparoscopic bilateral tubal ligation, using data from the New York State Department of Health's Statewide Planning and Research Cooperative Systems (SPARCS).

With as senior author, they identified 8,048 women who had hysteroscopic sterilizations with Essure and 44,278 who had laparoscopic sterilizations from 2005 to 2013.

Essure is a small nickel-titanium coil with a stainless steel coil inside it, which is inserted through the cervix and implanted in the fallopian tube. There, it triggers tissue growth that eventually blocks the tube to prevent sperm from meeting an egg. In 2013, it accounted for about one-quarter of all female sterilization procedures in the U.S.

Sedrakyan and colleagues found the implant method required 21 more reoperations per 1,000 patients than surgical sterilizations. And one in every 50 patients who received the devices, advertised as "noninvasive," later had an additional surgery. The elevated risk of reoperation occurred in all age groups and in patients with a history of pelvic inflammatory disease, noted the study.

"Mostly, of course, [the reoperation] is a second laparoscopic approach to fix the failure of the implant or complications resulting from the implant," Sedrakyan told 乌鸦传媒. "Reoperation" could also included removing the fallopian tubes or uterus.

But contrary to patient reports -- highlighted in public testimony at a recent FDA advisory panel meeting -- there did not appear to be an increased risk of unintended pregnancy among Essure recipients (odds ratio 0.84, 95% CI 0.63-1.12).

The advisory committee meeting was held after the agency received a wave of adverse events reports related to the device, including unusually high numbers of reports from patients. Women complained of severe abdominal pain, bleeding irregularities, migraines, painful sex, autoimmune disorders, extreme fatigue, psoriasis, perforation of the uterus, and even narcolepsy and cataplexy.

a professor of biostatistics and medical informatics at the University of Wisconsin-Madison, and a member of the FDA advisory panel, said that the same inflammatory reaction that triggers tissue growth within the fallopian tubes -- a response to the device's polyethylene terephthalate coating, (the same material who's use in bottled beverages has been debated) -- may also be driving these side effects.

He told 乌鸦传媒 in an email, "This inflammatory response is intentional -- however, how can we be assured that it is limited? And do we have enough information to intentionally invoke an inflammatory response in the abdomens of healthy women when we have reasonably safe alternatives?"

The panel strongly recommended the agency revise the label, establish stronger guidance, and develop a national patient registry to track the rate of pregnancies and adverse events.

Sedrakyan endorsed the idea of such a registry. "We have to finally recognize that there's a societal need to have this kind of national data," he said.

He added that, although the current study covers only one state, it is still broad enough to be generalizable.

One limitation was the difficulty in targeting the reason for each reoperation. The surgeries that follow initial implantation are more complex then the first procedure and, Sedrakyan said, "you can imagine [they] might not be as well-coded."

Chappell, who expressed concern at the September meeting that the Essure device had been approved without a randomized clinical trial, appeared impressed with Sedrakyan's research.

"The reoperation study wasn't randomized, but the effect (10-fold) was huge. Thus, even in the absence of randomization, this is quite worrisome . Similar effect sizes were seen in smoking vs. lung cancer in studies which, by necessity, couldn't be randomized, and they were believable."

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