A diaphragm is a shallow, dome-shaped barrier device made from flexible silicone or latex. This reusable contraceptive is designed to be placed deep inside the vagina before sexual activity to prevent pregnancy. It functions by physically covering the cervix, which is the entrance to the uterus. The diaphragm is categorized as a reversible, user-controlled method of contraception.
Mechanism of Action and Required Spermicide
Its primary function is as a physical barrier, forming a seal over the cervix to block the passage of sperm into the uterus. The flexible rim of the device is designed to fit snugly against the vaginal walls, ensuring the cervix remains completely covered.
For the diaphragm to be effective, it must always be used in conjunction with a spermicidal gel or cream. This chemical agent is applied to the inside of the dome and around the rim before insertion. Spermicide acts by immobilizing or killing the sperm.
The diaphragm holds the spermicide directly against the cervical opening. This placement ensures that any sperm that might bypass the physical barrier are immediately exposed to the chemical agent. Without the use of spermicide, the diaphragm’s effectiveness in preventing pregnancy is significantly reduced.
Obtaining the Right Fit and Proper Placement
Diaphragms are not a one-size-fits-all product and require a prescription and professional fitting from a healthcare provider. A doctor or nurse measures the distance between the posterior wall of the vagina and the pubic bone to determine the correct diameter of the device. Getting the right fit is important because a diaphragm that is too small may dislodge, while one that is too large can cause discomfort or fail to seal.
During the fitting process, the healthcare provider confirms that the anterior rim sits securely behind the pubic bone and that the cervix is fully covered by the dome. The user is then trained to insert the diaphragm by folding it in half, sliding it into the vagina, and pushing it until it covers the cervix. Correct placement is confirmed by checking that the dome is over the cervix, which feels firm and round, similar to the tip of a nose.
The diaphragm can be inserted up to two hours before intercourse, but if a longer period elapses, additional spermicide should be applied into the vagina without removing the device. The diaphragm must remain in place for a minimum of six hours after the final act of intercourse to allow the spermicide to kill all residual sperm. It should never be left in the body for longer than 24 hours due to safety concerns.
Success Rates and Health Implications
The effectiveness of the diaphragm is measured by its failure rate, which varies significantly between perfect use and typical use. With perfect use, the diaphragm prevents pregnancy in approximately 92 to 94 percent of users over one year. This translates to an estimated failure rate of six pregnancies per 100 users annually.
However, under conditions of typical use, which account for real-world errors like improper fitting or inconsistent spermicide application, the effectiveness rate drops to approximately 82 to 88 percent. This means that 12 to 18 people out of every 100 using the diaphragm will experience an unintended pregnancy within a year. The diaphragm provides no protection against sexually transmitted infections (STIs), and a condom is recommended to reduce this risk.
A rare but serious health implication is the risk of Toxic Shock Syndrome (TSS), associated with leaving the diaphragm in place for more than 24 hours. The increased risk of Urinary Tract Infections (UTIs) is another recognized side effect, as the rim of the diaphragm can press against the urethra, potentially interfering with bladder emptying. Some individuals may also experience irritation or allergic reactions to the latex material of the diaphragm or the chemicals in the spermicide.
Why Choose a Non-Hormonal Barrier Method
The diaphragm is an appealing option for individuals who want to avoid systemic hormonal contraceptives. Since it contains no hormones, it does not alter the natural menstrual cycle or cause side effects such as mood changes or weight fluctuations. This makes it a suitable choice for those who are sensitive to hormones or who are breastfeeding.
Because the diaphragm is reusable, it can be a cost-effective choice over time compared to methods that require frequent re-purchasing. The user maintains complete control over the device, inserting it only when contraception is needed. This immediate reversibility allows for a quick return to fertility as soon as the device is discontinued.