Biomechanics and suction force of menstrual cups: implications for IUD users

The concurrent use of menstrual cups and intrauterine devices (IUDs) is increasingly common due to the ecological, economic, and health benefits associated with menstrual cups. Understanding these biomechanical factors is essential to ensure patient safety and effective contraceptive use. A narrative review of existing literature was conducted to evaluate the biomechanical mechanisms involved in menstrual cup usage among IUD users. Published studies, case reports, and clinical observations were analysed with a focus on suction pressure, vaginal seal formation, force displacement, and user-related factors. Variations in anatomical characteristics, menstrual cup design, IUD type, and insertion–removal techniques were examined to assess their influence on IUD stability and expulsion risk. The review indicates that menstrual cups can generate negative pressure within the vaginal canal, which may exert upward forces on IUD strings and the device itself. Improper breaking of suction during cup removal and direct traction on IUD strings were identified as key contributors to IUD displacement and expulsion. The combined use of menstrual cups and IUDs presents potential biomechanical risks, particularly related to suction forces and improper removal techniques. While menstrual cups remain a safe and environmentally sustainable option for menstrual hygiene, increased awareness, proper user education, and careful consideration of cup design and IUD string management are essential. Further clinical and biomechanical studies are needed to establish standardized guidelines and minimize complications among IUD users who choose menstrual cups.