Julie Tietel, 52, went to the emergency room at St. Francis Hospital in Federal Way last Wednesday with flu-like symptoms and severe abdominal pain, said Monica Brookens, 27, of Edgewood, the News Tribune reported.
Hospital staff performed a chest X-ray on Tietel and gave her painkillers before sending her home to rest.
Tietel returned to the emergency room Thursday because her condition hadn't improved.
She was admitted to the hospital's intensive care unit, shortly before her organs failed. A doctor told her family Tietel had necrotizing fasciitis, or flesh-eating bacteria, and had contracted it possibly from a shaving cut on her leg, Brookens said.
Tietel was rushed into surgery, but later died.
Hospital spokesman Gale Robinette couldn't discuss specifics about the case because of federal privacy laws. The King County Medical Examiner had not yet determined Tietel's cause of death Monday night.