I'm not sure about that - it was common sense "gun shot wound" and a quick Google search found plenty of medical texts duscussing "birdshot" as GSW:
"Birdshot at a Moderate Distance
a 12-guage shotgun loaded with no. 6 Birdshot has a muzzle velocity of 1,300 ft/sec.
When fired from a distance of 12 feet, the shot will penetrate a 4-in-thick telephone book, producing a hole with a 2.4-in. diameter and releasing more than 2,000 ft-lb of energy
An M-16 Rifle has a Muzzle Energy of 1,250 ft-lb
The Shotgun delivers much greater energy to a target at close range than does the M-16"
http://www.ispub.com/ostia/index.php?xmlPrinter=true&xmlFilePath=journals/ijrdm/vol3n2/gsw.xml
I heard that the injured guy has actual physical welts from the shot.