“Like little elves in my belly, just punching, kicking, beating up my organs.” This is how Shea O’Donnell, a psychology graduate student at San Diego State University, used to describe pain from a disease called endometriosis to their mom when they were 12 years old. Years later, they still contend with digestive issues, back pain, and abdominal and vaginal cramping, almost like a “very painful flu.”

It’s estimated that about one in 10 people born with uteruses suffer from endometriosis, which occurs when tissue similar to the lining of the uterus grows in other parts of the body, often forming painful lesions.

People who have it deal with constant and irregular “flare-ups,” when symptoms become unbearable. Sufferers typically see four to five doctors over a period of about seven years before they get an accurate diagnosis, which can only be achieved through invasive surgery.

Read the full story in Scientific American.

Meghan McDonough is a filmmaker and journalist based in Brooklyn, New York.

Co-published with Scientific American.