Period blood has long been thought of as ‘stinky and useless’, but startups are exploring using the fluid to test for a wide range of health conditions – including difficult-to-diagnose endometriosis Somewhere in the US a woman on her period pulled out her dripping, saturated tampon. But instead of wrapping it in toilet paper and tossing it into a bin, she put the tampon in a special plastic sample container, screwed the lid on tight and mailed it to an address in Oakland, California. The