A surgical stapler that may have a head assembly, a stapling assembly, a shield, a base head, a handle assembly, and a shaft assembly. A head assembly may have an anvil and anvil shaft, as well as a stapling assembly. A stapling assembly may have a trocar that can be removeably detachable with the anvil, a cannula extension, and a plurality of staples. A shield may be configured to retract from a first extended position where the shield generally covers the stapling assembly or the head assembly, to a second retracted position where the shield generally exposes the stapling assembly or the head assembly. The shield may be integral with the stapler, or provided after-market as an add-on. A surgical stapler may additionally or alternatively include an air or gas pump assembly that can be used to insufflate the rectum and intestinal tract during insertion and advancement of the stapler.