A New Way to Spot Menstrual Blood and Vaginal Fluid in Crime Scenes

In crime scenes, menstrual blood and vaginal fluid often show up alongside semen. This makes it tough for investigators to pinpoint exactly what's what. But now, there's a new tool in town: a 4-plex MSRE-PCR system. This system uses four markers to detect these fluids. It's like a detective that can tell the difference between menstrual blood, vaginal fluid, and other body fluids. The markers are cleverly named: a positive control, a digestive control, a menstrual blood-specific marker, and a vaginal fluid-specific marker. This system was put to the test with various samples. Menstrual blood and vaginal fluid samples were correctly identified. Even when mixed with other body fluids like saliva, semen, and blood, the system didn't get confused. It correctly showed no menstrual blood or vaginal fluid markers. This is important because sometimes, these markers can pop up in non-target body fluids like urine, nasal fluid, and skin. But the system handled it like a pro. Now, here's where it gets interesting. The system's sensitivity changes based on the day of the menstrual cycle. On the first day, it needs just 1 ng of DNA to correctly identify menstrual blood. But by the fifth day, it needs 1. 5 ng. This is because the methylation levels at the markers change throughout the cycle. For vaginal fluid, the system needs at least 0. 5 ng of DNA for a confident identification. The system was also tested on different materials found in crime scenes. Menstrual blood samples on seven types of materials were all correctly identified. Even simulated mixed samples of menstrual blood and vaginal fluid were tested and the results were spot on. But here's a question to ponder: how reliable is this system in real-world scenarios? While the tests show promising results, more research is needed to see how it holds up in actual crime investigations. After all, crime scenes are messy and unpredictable. This system might need some tweaks to handle the chaos.