They are investigating “the circumstances around the injury”, which took place at the lower end of Le Truchot in St Peter Port, in the early hours of 1 December.
The man is said to have been standing along the front of a blue doorway at the rear exit of the nightclub.
Anyone with information is asked to contact PC 138 Peter Falla on 725111, or Crimestoppers anonymously on 0800 555 111.
Pictured top: The man was stood along the lower end of Le Truchot.