New data emerges on one-size diaphragm

Effectiveness rate rivals traditional devices

The contraceptive options for women who cannot use hormonal methods might soon expand if regulatory approval is given to a new single-size diaphragm. Results of a two-year multi-site study of 450 U.S. couples indicate the effectiveness rates of the SILCS single size, contoured diaphragm, now in development, are similar to traditional diaphragms. Results of the pivotal trial were presented at the 2011 Reproductive Health Conference in Las Vegas.1

The device's single-size design, developed by PATH, a Seattle-based international health advocacy organization, eliminates the need for a clinical fitting. The SILCS diaphragm, made of silicone, was developed to improve reproductive health in low-resource settings. In those low-resource settings, women have a limited range of contraceptive methods, and diaphragms are not available. It also might provide another option for women in developed countries, particularly for those who cannot or do not want to use hormonal methods or an intrauterine device.

"High rates of unintended pregnancy and discontinuation of current contraceptive methods suggest that existing contraceptive methods do not adequately meet the reproductive health needs of all women," said Michael Free, PhD, PATH's vice president and senior advisor for technologies in a press release accompanying the study results. "This newly designed, discreet, and reusable cervical barrier could expand women's options for nonhormonal protection, thereby improving women's reproductive health especially in low resource settings."

Not your mother's device

The device is "not your mother's diaphragm." Those words come from Jill Schwartz, MD, medical director at Arlington, VA-based CONRAD, an international reproductive health research organization and study principal investigator.

Development of the SILCS diaphragm arose as a response to women calling for a broader choice of contraceptive methods that are under their control, can be easily stopped and started, and nonhormonal, thus eliminating side effects. Health advocates also are interested in its potential as a dual protection method, providing protection against pregnancy and such sexually transmitted infections as HIV.

The pivotal trial was designed as a multi-center trial, looking at 450 U.S. couples using the SILCS device with gel for six months. Study visits were held at baseline, after one cycle, three cycles, and six cycles (190 days). The study was modeled in a similar design to an earlier investigation that looked at use of a fitted diaphragm.2

Couples were randomized into two study arms; 300 couples used the SILCS device with BufferGel, a microbicidal spermicide under development, while 150 couples used the device with Gynol II (Revive Personal Products, Madison, NJ), a nonoxynol-9 spermicide. The study objectives included a six month typical use pregnancy probability; a safety analysis of the SILCS device, including colposcopy and microflora subset; and an analysis of the feasibility of its over-the-counter use and fit.

In comparing the SILCS against the Ortho All-Flex diaphragm (Ortho-McNeil-Janssen Pharmaceuticals, Titusville, NJ) six-month typical use pregnancy rates (with 95% confidence interval), couples using the SILCS with Buffer Gel recorded a rate of 9.6 (5.5-13.6), compared to the All-Flex/Buffer Gel rate of 10.1 (7.1-13.1). For those who used the SILCS device with Gynol II spermicide, a rate of 12.5 (5.4-19.5) was recorded. This number compares to 12.3 (7.7-16.9) for the All-Flex diaphragm with similar spermicide.1

Ease of use eyed

How easy is it for healthcare providers to instruct women on proper use of the SILCS diaphragm? So far, women have only used the SILCS diaphragm in clinical trials in which they were given instructions that are similar to a standard sized diaphragm, says Schwartz. The next step will be to see how clinicians and women interact with the SILCS diaphragm once it becomes commercially available, she notes.

"The biggest difference with this device is that since it is a single-size, a pelvic exam to assess size is not required," Schwartz notes. 

In the pivotal study, women were introduced to the device using printed instructions only, Schwartz notes. Most women were able to correctly insert, remove, and check correct position of the device by simply using the instructions. For women who had difficulty positioning the device or were not confident, counseling by the clinician helped most women achieve successful fit, she states.

"The clinician and the woman can assess the correct SILCS position according to four simple criteria: cervix covered, device behind pubic bone, device does not protrude from the vagina, and device comfort," says Schwartz. "These simple fit criteria should help women to feel confident using this method."

Participants in the study reported high ratings for ease of use and comfort for both females and their partners, which should be noted as an important feature, says Schwartz. "The only methods that work are the kind that women will actually use," she observes.

What's the next step?

The SILCS device is not yet approved by regulatory authorities, so it is not yet commercially available, says Schwartz. Developers are moving toward seeking such approval, though.

PATH licensed the SILCS Diaphragm design to Kessel Marketing & Vertriebs GmbH (Kessel) of Frankfurt, Germany, in late 2010, states Schwartz. Kessel is working toward CE Mark certification, which will allow the product to be introduced through the company's existing distribution network in European Union countries, she states.

Kessel, CONRAD, and PATH will work on the submission to the U.S. Food and Drug Administration after European regulatory approval is granted, Schwartz says.


  1. Schwartz J. SILCS pivotal data: implications for MPTs. Presented at the 2011 Reproductive Health conference. Las Vegas; September, 2011.
  2. Barnhart KT, Rosenberg MJ, MacKay HT, et al. Contraceptive efficacy of a novel spermicidal microbicide used with a diaphragm: a randomized controlled trial. Obstet Gynecol 2007; 110:577-586.