A diaphragm is a reusable, dome-shaped barrier contraception device, typically made of soft silicone or latex. It has a flexible rim that allows it to be compressed for insertion into the vagina. Its primary function is to prevent pregnancy by physically blocking sperm from entering the cervix, the opening to the uterus. This non-hormonal method requires insertion before intercourse and removal afterward.
Physical Mechanism of Action
The diaphragm’s contraceptive efficacy relies on a two-part system: a physical barrier and a chemical agent. The dome of the device is designed to be seated deep within the vagina, completely covering the cervix. This placement creates a physical obstruction that prevents sperm from traveling into the upper reproductive tract where fertilization occurs.
The physical barrier must be supplemented with a spermicidal jelly or cream applied to the diaphragm before insertion. This chemical component is spread across the dome and rim, ensuring that it rests directly against the cervix. The spermicide’s role is to immobilize or destroy any sperm that might manage to bypass the physical barrier of the rim.
Spermicide is mandatory for the diaphragm to function reliably. The device holds the spermicide near the cervical opening, maximizing its effect on any ejaculate deposited in the vagina. This dual mechanism ensures the diaphragm acts as an active chemical defense against conception, not simply a physical shield.
Obtaining and Customizing the Diaphragm
A diaphragm requires a prescription from a healthcare provider and is not available over the counter. The process involves a fitting to determine the correct size and type for the user. Providers use fitting rings to measure the distance between the posterior vaginal vault and the pubic bone, which dictates the necessary diameter.
Correct sizing is important for both comfort and contraceptive effectiveness. A diaphragm that is too small may dislodge easily, while one that is too large can cause discomfort or pressure. The proper fit ensures that the rim creates a complete seal and remains securely positioned over the cervix even during intercourse.
Diaphragms come in various designs (arching spring, coil spring, or flat spring) and are typically made of silicone. Refitting is necessary if a person gains or loses significant weight (more than 10 to 15 pounds), or after a full-term pregnancy or pelvic surgery. These events change the internal dimensions of the vagina, necessitating a new size to maintain a secure fit.
Proper Usage and Timing
For effectiveness, the diaphragm must be inserted before any sexual penetration. It can be placed up to two hours prior to intercourse, with spermicide applied to the dome and rim beforehand. The user must confirm correct positioning, ensuring the cervix is fully covered by feeling through the dome.
If more than two hours pass between insertion and intercourse, or if a second act occurs, an additional application of spermicide is required. This fresh spermicide must be inserted into the vagina without removing the diaphragm to maintain the chemical barrier. Using a separate applicator helps avoid disturbing the device’s position.
Following intercourse, the diaphragm must remain in place for a minimum of six hours. This waiting period allows the spermicide time to neutralize all sperm in the vaginal canal. The device should not be left in for longer than 24 hours, as extended wear increases the risk of infection. Removal is achieved by hooking a finger under the front rim and gently pulling it out.
Effectiveness and Safety Considerations
When used consistently and correctly with spermicide, the diaphragm has a perfect use failure rate of about 6% over one year. However, because user error is common, the typical use failure rate ranges from approximately 12% to 18% annually. The effectiveness is highly dependent on adhering to the specific instructions for timing, spermicide application, and proper fit.
Diaphragm users may experience an increased risk of Urinary Tract Infections (UTIs). The rim of the device can press against the urethra, potentially interfering with complete bladder emptying or facilitating the transfer of bacteria. If the diaphragm is left in place for longer than 24 hours, there is a very rare but serious risk of Toxic Shock Syndrome (TSS).
To maintain the device, it should be washed with mild soap and warm water, rinsed thoroughly, and air-dried after each use. It should be stored in its case away from heat and direct sunlight, and checked regularly for tears or holes. The device generally needs replacement every one to two years, even with careful maintenance.