A menstrual cup shifting, losing its seal, or being partially expelled during a bowel movement is a common concern. This displacement is a predictable physiological response stemming from the body’s internal architecture and the mechanics of defecation, not a sign of improper use. Understanding the physical forces and anatomical relationships at play provides the foundation for solving this issue. Solutions involve addressing both the equipment and the user’s technique.
The Anatomical Connection
The primary reason a menstrual cup moves during a bowel movement is the intimate proximity and shared muscular support of the pelvic organs. The vagina and the rectum sit side-by-side, separated only by the rectovaginal septum. This anatomical arrangement means that pressure changes in one area significantly affect the other.
Defecation requires the coordinated action of the abdominal and pelvic floor muscles, which form a supportive structure. The main muscle group involved is the levator ani, including the pubococcygeus muscle, which surrounds the openings for the urethra, vagina, and rectum. When straining to pass stool, intra-abdominal pressure increases, pushing downward on all pelvic contents, including the vaginal canal where the cup is seated.
The act of pushing causes the pelvic floor muscles, particularly the pubococcygeus, to contract and then relax to allow stool to pass. This muscular movement directly impacts the vaginal walls gripping the cup. The downward pressure and the momentary relaxation of the muscles can break the cup’s suction seal or push it lower in the canal. If the cup is sitting particularly low, the downward force can even cause it to be expelled completely.
Adjusting Cup Choice and Placement
Firmness
One effective way to counter downward pressure is by optimizing the cup itself. The firmness of the cup’s silicone plays a significant role in its ability to resist being squeezed or displaced. A softer cup is more susceptible to collapsing under the strain of increased intra-abdominal pressure, causing the seal to break.
Switching to a firmer cup helps the rim maintain a robust seal against the vaginal walls, making it less likely to be compressed or pushed down during straining. However, a cup that is too firm may press uncomfortably on the bladder or rectum, potentially causing discomfort. A medium-to-firm option often provides the best balance of comfort and stability.
Size and Seal
The cup’s size and length relative to anatomy are also factors. A cup that is too long for a low cervix may sit too close to the vaginal opening, making it an easier target for expulsion when pressure is applied. Conversely, a cup that is too narrow might not create a wide enough seal to withstand muscular squeezing. Ensuring the cup is fully open and sealed after insertion is paramount, as a partial seal will fail instantly under pressure.
Placement
Proper placement involves positioning the cup higher in the vaginal canal, away from the pubococcygeus muscle contractions near the opening. For those with a high cervix, inserting the cup so the cervix rests inside it can provide an anchor point, stabilizing the cup against downward force. This positioning must still allow for comfortable removal, which is why assessing your cervix height is a necessary first step.
Managing Pelvic Floor Pressure
Modifying the technique used during a bowel movement can significantly reduce cup displacement. The primary goal is to avoid aggressive straining or pushing, which is the main driver of problematic intra-abdominal pressure. Allowing the body to do the work with minimal effort is generally healthier for the pelvic floor.
Improving posture on the toilet can naturally reduce the need to strain. Using a small stool or squatting device elevates the knees above the hips, mimicking a natural squatting position. This posture helps straighten the anorectal angle, allowing for a smoother, less effortful passage of stool and minimizing the downward force exerted on the cup.
When the urge to defecate occurs, consciously try to relax the pelvic floor muscles around the vagina, directing the push toward the rectum only. This focuses the muscular effort where it is needed and reduces the involuntary contraction that pushes the cup. If the cup consistently moves, some users find it easiest to simply remove, empty, and reinsert the cup after a bowel movement.