A leaking menstrual disc almost always comes down to one of three things: the disc isn’t positioned correctly behind your cervix, the front rim isn’t tucked securely behind your pubic bone, or the disc diameter doesn’t match your anatomy. The good news is that most leaks are fixable once you identify which problem you’re dealing with.
The Disc Isn’t Sitting Behind Your Cervix
The most common reason a disc leaks heavily, as if it’s not catching anything at all, is that it’s sitting in front of the cervix rather than below and behind it. Your cervix is where menstrual blood flows from. If the disc is pressed flat against the front of the cervix instead of cupping underneath it, blood simply flows right past the disc and out.
This happens because of insertion angle. If you push the disc straight up during insertion, it tends to land in front of the cervix. Instead, angle the disc down and back toward your tailbone as you slide it in. That rear-facing angle guides the back rim into the vaginal fornix, the deeper space just beneath the cervix where the disc is designed to sit. Once the back of the disc is as far back as it can go, use your thumb or index finger to push the front rim up and tuck it behind your pubic bone. You should feel a small notch or ledge there where the rim locks into place.
The Front Rim Keeps Coming Untucked
If the disc feels fine at first but then shifts, causing discomfort and leaking during normal activity, the front rim is slipping out from behind your pubic bone. This is extremely common with new disc users who are understandably cautious about how far up the disc needs to go. The answer: farther than you think.
After inserting the disc and pushing it back, place your index finger on the front rim and firmly press it up and behind the pubic bone. You’re looking for that rim to hook securely behind the bone, not just rest loosely against it. If you can still easily feel the rim sitting low in your vaginal canal, it’s not tucked high enough. A properly placed disc should feel like it disappears. You shouldn’t notice it during regular movement.
If you’re confident the tuck is right and the disc still slips during everyday activities like walking or sitting, the issue is likely sizing rather than technique.
Your Disc Diameter Is Wrong
Menstrual discs come in a range of diameters, typically from about 56 mm on the small end up to 70 mm on the large end. A disc that’s the wrong width for your body can leak even with perfect placement.
A disc that’s too large acts like a tightly wound spring. It tucks into place but there isn’t quite enough room for it, so any sudden movement, a hard sneeze, a cough, or a squat at the gym, pops it loose. If your disc seems to stay put during calm moments but dislodges the second you exert yourself, or if it feels like there isn’t enough room for it during insertion and it keeps springing out, try sizing down.
A disc that’s too small presents the opposite problem. It slides in easily and seems to tuck fine, but it has too much room to move around. It can slip past the pubic bone during normal activity because it doesn’t fit snugly enough against the vaginal walls. If your disc continually dislodges from behind the pubic bone without much provocation, you likely need a larger diameter.
For reference, some popular discs and their diameters: the Saalt Disc comes in 56 mm (small) and 66 mm (regular), the Hello Disc is a single 68 mm size, the Flex Disc is 69 mm, and brands like Cup&Co offer 65 mm and 70 mm options. If you’re between sizes or unsure, a brand that offers two sizes gives you more room to experiment.
Auto-Dumping vs. Actual Leaking
Before assuming something is wrong, it helps to know that menstrual discs are designed to release blood in certain situations, a feature called auto-dumping. When you sit on the toilet and bear down (to pee or have a bowel movement), your pelvic floor muscles contract slightly. That contraction shifts the disc just enough to let collected blood flow out. Once you relax, the disc settles back into position on its own.
Auto-dumping is normal and only happens on the toilet, triggered by that specific bearing-down motion. If you notice blood releasing only when you use the bathroom, your disc is working as intended. But if blood is releasing while you’re walking, laughing, coughing, or exercising, that’s a leak caused by poor positioning or incorrect sizing, not auto-dumping.
A Tilted Uterus Can Complicate Placement
About 20% of people have a retroverted (tilted) uterus, where the uterus angles backward instead of forward. This can make disc placement trickier because the cervix may sit further back against the vaginal wall, leaving less room for the disc to tuck underneath it.
Having a retroverted uterus doesn’t automatically rule out disc use, but it may require a different insertion approach. One technique that helps is “scooping”: point the disc slightly downward during insertion to guide it below the cervix before tucking the front rim. If that doesn’t work, some users have success with the “upside down” method, inserting the disc with the collection basin facing up, then using a finger to flip the front rim down and forward so the disc rotates into the correct position beneath the cervix. This can help the disc clear a cervix that sits in an unusual spot.
If you’re unsure about your uterus position, your gynecologist can tell you during a routine exam. You can ask whether a diaphragm would fit behind your cervix, since diaphragms sit in a similar position to menstrual discs.
Postpartum and Pelvic Floor Changes
If a disc that previously worked great has started leaking, consider whether your body has changed. After childbirth, the vagina and cervix are typically wider than before pregnancy, which can mean a disc that once fit perfectly is now too small in diameter. Sizing up often solves this.
Pelvic floor muscle tone also plays a role. While the disc doesn’t rely on muscle grip the way a menstrual cup does (it rests in the fornix and hooks behind the pubic bone), weak pelvic floor muscles can contribute to pressure changes that shift the disc during activity. If you’re also experiencing symptoms like urinary leakage or pelvic pressure, strengthening your pelvic floor may help with disc stability too.
A Quick Troubleshooting Checklist
- Heavy, constant leaking as if the disc catches nothing: The disc is likely sitting in front of your cervix. Reinsert angled toward your tailbone so it slides behind the cervix.
- Disc slips down during calm, everyday activity: The front rim isn’t tucked high enough, or the disc is too small in diameter.
- Disc pops out during exercise, sneezing, or coughing: The disc is likely too large and doesn’t have enough room to stay stable. Try a smaller diameter.
- Small amounts of blood only when using the toilet: This is auto-dumping, not a leak. The disc is working normally.
- Disc worked before but leaks now after pregnancy: Your anatomy has changed. Try a larger disc size.
Most people who struggle with leaking find their fix within the first two or three cycles of experimenting with technique and sizing. The learning curve is real, but once the disc clicks into the right spot, it tends to stay put.