(Sports Network) - A sprinter has taken herself off the United States Olympic track and field team after a positive doping test.

Debbie Dunn won't race in London after a test at U.S. trials showed the likely presence of an anabolic steroid, the Chicago Tribune reported Friday.

Dunn placed fourth in the 400-meter dash at trials, missing an automatic spot on the roster, but was added to the pool of runners for the 1,600-meter relay.

She said in a statement that she was withdrawing her name to avoid being a distraction.

07/13 17:29:12 ET