In 2008, O'Brien played Marie, a nurse, in the award-winning television drama, Whistleblower, based on actual events at Our Lady of Lourdes Hospital in Drogheda, County Louth in the 1990s, where Michael Neary, an Irish consultant obstetrician/gynecologist, was struck off the Register of Medical Practitioners for professional misconduct relating to the performance of caesarian hysterectomies.