Menstrual cups prevent leaks by creating a gentle vacuum seal against the walls of the vaginal canal. This seal forms when the cup is inserted, fully opened, and rests against the vaginal musculature to collect menstrual fluid. If the cup is not fully opened or the seal is compromised, leakage often results. Successfully maintaining the seal depends on correct insertion technique, the physical dimensions of the cup, and accommodating individual anatomy.
Technique Issues Preventing Suction
The most common reason for a failed seal is an error during insertion that prevents the cup from fully expanding inside the body. Rushing insertion can leave the cup partially compressed or folded against the vaginal wall. The cup must spring open completely to create the necessary 360-degree seal around the rim.
The folding method used significantly impacts the cup’s ability to open when released. Folds like the “C-fold” or “7-fold” keep the cup compact, but a cup that is too soft may lack the tension to fully unfold. A fold like the “punch-down” fold, which creates a smaller, firmer insertion point, may allow the rim to spring open more easily once inside.
Improper insertion angle is another frequent technical issue. Since the vaginal canal slopes backward toward the tailbone, the cup should be aimed in this direction, not straight upward. Inserting the cup at the wrong angle can cause it to catch on the vaginal wall or sit too close to the pubic bone, leaving the rim indented or collapsed. Running a clean finger around the rim immediately after insertion checks for dents or folds and ensures the cup has fully expanded.
Ensuring Proper Cup Fit
If insertion technique is correct but the seal fails, the physical specifications of the cup are often the culprit. The diameter of the cup’s rim must be appropriate for the individual’s vaginal width to maintain a consistent seal. A cup that is too narrow may not exert enough pressure, while one that is too wide can be difficult to open or cause discomfort.
The length of the cup is also a factor, as it should ideally rest just beneath the cervix. A cup that is too long may press uncomfortably against the cervix or sit too high in the vaginal fornix, where the wider canal prevents a tight seal. Conversely, a cup that is too short may sit too low, leading to leakage or an unstable position.
Cup firmness, or the rigidity of the material, plays a significant role in seal integrity. A cup that is too soft may be easily crushed or indented by the surrounding vaginal and pelvic floor muscles, preventing it from springing open or collapsing the seal during activity. Firmer cups provide more outward force, making them easier to open and more resilient against muscle pressure.
Anatomical Considerations for Placement
Individual anatomy presents variations that affect cup placement and the resulting seal. The position of the cervix, which changes throughout the menstrual cycle, is a primary consideration. If the cup bypasses a low-sitting cervix, menstrual flow may run down the outside, causing a leak even if a seal is formed.
For those with a high cervix, a shorter cup may migrate upward, making removal difficult and causing the rim to sit in a less secure part of the canal. The strength of the pelvic floor muscles is another anatomical variable. Highly toned muscles can squeeze and indent a softer cup, breaking the seal and often necessitating a switch to a firmer model.
If the pelvic floor muscles are weaker, the cup may slide down the canal, losing suction as it descends. In these cases, the cup may need to be positioned higher within the vagina so surrounding muscles can provide sufficient support for the seal. Proper placement ensures the cup is seated in a stable position where the vaginal walls support the rim’s pressure.
Immediate Troubleshooting for a Broken Seal
If the cup is inserted but a seal has not formed, several immediate steps can encourage it to open fully and secure the seal without requiring full removal and reinsertion:
- Gently rotate the cup one full 360-degree turn by grasping the base, not the stem. This helps the rim catch the vaginal wall, encouraging it to fully expand and un-dent any collapsed areas.
- Gently tug down on the stem after insertion. This action helps create a vacuum effect, pulling the cup into a tighter seal against the walls.
- If the cup feels partially closed, bear down slightly with the pelvic muscles, as if initiating a bowel movement. Releasing the muscles then allows the vaginal walls to conform around the cup’s rim, helping it seat and seal correctly.
- If an indentation is found, press inward on the vaginal wall just next to the dent. This can provide the space needed for the cup to fully pop open.