Inserting a diaphragm is similar to inserting a tampon: you fold the device, slide it into the vagina, and push it back and up until it sits behind the pubic bone and covers the cervix. The process takes about a minute once you’ve practiced a few times, and you can insert it up to two hours before sex. Here’s how to do it correctly.
Before You Start: Spermicide and Handwashing
Wash your hands thoroughly with soap and water. Then apply about a tablespoon of spermicide gel or cream to the inside of the dome (the side that will sit against your cervix) and around the rim. Spermicide is what makes the diaphragm significantly more effective. Without it, the device is just a physical barrier; with it, the failure rate drops from 12% with typical use to 6% with perfect use over the course of a year.
If you’re using a Caya diaphragm (the one-size-fits-most option now more common than traditional fitted models), it comes with grip dimples and a removal dome that make it easier to handle. The spermicide goes in the same place regardless of which type you have.
Finding a Comfortable Position
Pick whichever position lets you relax your pelvic muscles and reach comfortably. The most common options are squatting with your knees apart, standing with one foot propped on a chair or the edge of a bathtub, sitting on the toilet, or lying on your back with your knees bent. Most people settle on a favorite after trying insertion a couple of times. The key is relaxing your muscles, because tension makes the vaginal canal narrower and insertion harder.
Step-by-Step Insertion
Hold the diaphragm dome-side down (spermicide facing up) and squeeze opposite sides of the rim together so it folds into a narrow shape, roughly like a taco. With your other hand, spread the labia, then slide the folded diaphragm into the vaginal opening. Guide it backward and upward toward the small of your back, pushing it as far as it will comfortably go.
Once the back edge of the rim is past the cervix, tuck the front edge up behind the ridge of your pubic bone. You should be able to feel that bony ledge with your fingertip right behind the front wall of the vagina. The diaphragm essentially sits in a diagonal line from behind the pubic bone to the back of the vaginal canal, creating a cup over the cervix.
If you’re using a Caya diaphragm, make sure the small arrow molded into the silicone is pointing toward your body when you insert it. The oval, contoured shape is designed to match the anatomy, so orientation matters.
Checking That It’s in the Right Place
After insertion, run your finger over the dome of the diaphragm. You should be able to feel your cervix through the silicone. It feels like a firm, rounded bump, often compared to the tip of your nose. The entire cervix should be covered by the dome, and the front rim should be tucked snugly behind the pubic bone. If you can feel the cervix beside the rim rather than underneath the dome, the diaphragm is off-center and needs to be repositioned.
The device shouldn’t feel uncomfortable once it’s in place. If it pinches or you’re very aware of it, it may be the wrong size (for traditional fitted diaphragms) or it may not be pushed back far enough. You and your partner should not be able to feel it during sex.
Timing: When to Insert and When to Remove
You can insert the diaphragm up to two hours before intercourse. If more than two hours pass before sex, add more spermicide without removing the device. If you have sex more than once, add another application of spermicide each time, again leaving the diaphragm in place.
After the last time you have intercourse, the diaphragm must stay in for at least six hours. This gives the spermicide time to neutralize any sperm. Do not leave it in for more than 24 hours total, because extended wear increases the risk of toxic shock syndrome, a rare but serious bacterial infection.
How to Remove It
Get into the same comfortable position you used for insertion. Slide your index finger into the vagina and hook it over the front rim of the diaphragm, the edge tucked behind your pubic bone. Pull it downward and out gently. If the suction feels tight, push one finger between the rim and vaginal wall to break the seal before pulling.
After removal, wash the diaphragm with mild soap and warm water, let it air dry, and store it in its case. Check it periodically for holes or thin spots by holding it up to light. A damaged diaphragm should be replaced.
One-Size vs. Fitted Diaphragms
Traditional diaphragms come in multiple sizes and require a healthcare provider to measure your vaginal canal and cervix position to find the right fit. The Caya diaphragm, now the more widely available option, uses a single contoured design estimated to fit about 80% of women. It can be purchased without a fitting appointment, though reproductive health organizations still recommend having a provider check that it covers your cervix correctly, especially the first time.
Caya is unlikely to fit well if you’ve previously been fitted for a traditional diaphragm that was size 85 mm or larger, or 60 mm or smaller. If you fall outside the middle size range, a provider can help you find the right option.
How Effective Is a Diaphragm?
With perfect use (correct placement every time, with spermicide, left in for the full six hours), 6 out of 100 women will become pregnant in a year. With typical use, that number rises to 12 out of 100. The gap between those numbers reflects real-life factors: occasionally skipping spermicide, removing the diaphragm too soon, or not checking placement. Consistent technique narrows that gap considerably.
Common Side Effects and Risks
The most frequently reported issue is an increased rate of urinary tract infections. The rim of the diaphragm presses against the urethra, which can make it easier for bacteria to enter the urinary tract. Urinating after sex and staying hydrated can help reduce this risk.
Some people experience skin irritation from the spermicide or from latex (if using an older latex model rather than silicone). Switching to a silicone diaphragm or a different spermicide brand often resolves this. Toxic shock syndrome is a theoretical risk with any device left in the vagina for extended periods, but it is very rare with diaphragms as long as you follow the 24-hour maximum.