A new investigation has found that thousands of women have reported serious health problems stemming from a permanent birth control device that has been on the market for 15 years and is still available.

Essure is supposed to work by irritating a woman's fallopian tubes, which creates scar tissue that blocks eggs from traveling from her ovaries to the uterus. But as Washington Post magazine contributor Jennifer Block reports, despite the fact that medical devices like it are supposed to undergo the most rigorous testing possible under federal regulations, many women experienced symptoms similar to severe autoimmune disease—and many still became pregnant.

After outcry from anti-Essure activists, the U.S. Food and Drug Administration held a hearing on the device in 2015, which led to it putting a "black box warning" about its possible side effects—one of the strongest actions the agency takes in warning the public about potential dangers of medication or devices.

Block joins WNYC host Kerry Nolan to discuss the problems with Essure and how such a problematic device made it to market in the first place.

You can read Block's story here and hear her on the podcast Reveal. The story was produced in partnership with The Investigative Fund at the Nation Institute