Yes, you can wear a menstrual cup through airport security, but you should be aware of how it interacts with body scanners. Menstrual cups are typically made of medical-grade silicone, which is a non-metallic material that is safe for both X-ray and Millimeter Wave scanners (the 3D "spinning" scanners). However, because the scanner detects "anomalies" on or inside the body, a full cup may occasionally trigger a yellow box on the security monitor in the groin area. If this happens, a female TSA agent will perform a targeted pat-down of the area to ensure the "anomaly" is not a prohibited item. Most travelers do not experience any issues, but for total peace of mind, some prefer to empty the cup just before entering the security line. It is perfectly safe to keep in your carry-on as well; it does not count as a liquid and does not need to be removed from your bag for screening.