Noninvasive female sterilization eyed
Noninvasive female sterilization eyed
American women who consider tubal sterilization as a permanent form of birth control but don’t want to undergo a surgical procedure may have such an option if an investigational device proves effective in clinical research.
Phase II studies of the Essure permanent birth control procedure (Essure pbc) are now under way at eight sites in the United States as well as five international sites, reports Charles Carignan, MD, vice president of clinical research and medical affairs at San Carlos, CA-based Conceptus, developer of the device.
Previously known as the Selective Tubal Occlusion Procedure (STOP), the Essure pbc involves the use of a proprietary microinsert device and catheter delivery system for minimally invasive transcervical tubal access. Conceptus plans to file for product approval from the Food and Drug Administration by the end of the second quarter of 2002. The Essure pbc is being marketed in Australia, Singapore, and Europe, and in November 2001 received market clearance for sales in Canada.
"The procedure was developed in order to have an alternative to the current surgical sterilization that typically requires general anesthesia and punctures into the abdomen, thus requiring several days to recover," says Carignan. "The goal was to have a procedure that could be performed in awake patients in an outpatient setting."
Tubal sterilization is the most common method of contraception used in the United States; 11 million women ages 15-44 rely on the method for birth control.1 Half of the 700,000 annual bilateral tubal sterilizations are performed postpartum and half as ambulatory interval (unrelated in time to a pregnancy) procedures.1
If the research shows that the Essure pbc is safe and effective, it will represent a "significant new option for women," says Amy Pollack, MD, MPH, president of EngenderHealth in New York City.
"I think the advantages of such a transcervical procedure — if it is permanent and as effective as an abdominal procedure — are that many more women will choose it and will be safe in their choice to use it, and that includes women who have any kind of medical contraindication to either anesthesia or an abdominal procedure itself, and also women for whom surgery is not a option [they would normally choose]," Pollack observes.
How does Essure work?
The Essure device consists of a stainless steel inner coil, a nickel titanium alloy outer coil, and polyethylene terephthalate (PET) fibers. The device length measures 4 cm. The inner coil attaches the device to a guidewire used for placement in the fallopian tubes. The outer coil anchors the microinsert in the fallopian tube, and the PET fibers are a mesh between the two coils.
The coil mechanism is inserted in a half-hour procedure called hysteroscopic sterilization that requires only local anesthetic. During the Essure pbc procedure, the device is inserted through the cervix into the fallopian tubes through a catheter that covers the guidewire, from which the device is then released. The device promotes tissue growth in the fallopian tubes that, over a three-month period, provides tubal occlusion.
Just-published data support the theorized mechanism of action of the Essure pbc device and demonstrate its ability to cause a tissue response that histologically shows a high rate of occlusion of the fallopian tube.2 The company plans further histology studies to support the data.
Will women use Essure?
Data published in a recent issue of the Australia and New Zealand Journal of Obstetrics and Gynecology look at the experiences of the first participants in one of two clinical studies under way.3 Of the 130 women who underwent device placement, 95% were between 31-39 in age. During the first three months, the women used an alternative form of contraception (oral contraceptives or barrier methods) to allow adequate time for a localized tissue ingrowth into the microinsert to occur. Three months after placement, all participants underwent a hysterosalpingogram to ensure stable device positioning and retention and to evaluate the extent of fallopian tube occlusion. If occlusion was achieved successfully, women were instructed to cease use of alternate contraception and to rely on the inserts for birth control.
Bilateral device placement was achieved in 111 of 130 (85%) women who underwent device placement attempts. According to the researchers, there have been no pregnancies reported in 1,894 woman-months of effectiveness. Adverse events preventing women from relying on the Essure pbc occured in fewer than 5% of women.
Women participating in the study found the device placement procedure to be highly acceptable. Of women wearing the device for up to two years, 97% rated it to be very good to excellent.
With the method now in the mid-stages of study, Pollack says she looks forward to more information and the experiences of more women in regard to the placement of the Essure pbc device and its long-term efficacy.
"From the reports that I have seen and what I have heard, the method itself shows significant promise in terms of being a favorable one," says Pollack. "We should all be excited about that possibility."
References
- Westhoff C, Davis A. Tubal sterilization: Focus on the U.S. experience. Fertil Steril 2000; 73:913-922.
- Valle RF, Carignan CS, Wright TC. Tissue response to the STOP microcoil transcervical permanent contraceptive device: Results from a prehysterectomy study. Fertil Steril 2001; 76:974-980.
- Kerin JF, Carignan CS, Cher D. The safety and effectiveness of a new hysteroscopic method for permanent birth control: Results of the first EssureTM pbc clinical study. Aust N Z J Obstet Gynaecol 2001; 41:364-370.
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