Not a Common Event
The sprint medley relay is an officially sanctioned event by the USA Track and Field Association, often held at the collegiate or high school levels to give athletes experience in running relays. The event is not offered at the Olympics, which reserves relays to the 4x100 and 4x400. The sprint medley relay isn't held at the NCAA or United States Track and Field championships, either. You may find it at special invitational events, such as the USA versus the World event held in April 2014.