A surgical stapling device is disclosed for performing circular anastomoses. The surgical stapling device includes a handle portion, an elongated body portion and a head portion including an anvil assembly and a shell assembly. The head portion includes an anvil assembly including a tiltable anvil which will tilt automatically after the device has been fired and unapproximated. The tiltable anvil provides a reduced anvil profile to reduce trauma during removal of the device after the anastomoses procedure has been performed. The stapling device includes an approximation mechanism including a rotatable knob, a screw having a helical channel and an anvil retainer. The helical channel includes a dwell portion for providing a tactile indication to a surgeon that the anvil retainer has been advanced to a position wherein the anvil assembly can be removed from the anvil retainer. A removable trocar for attachment to the anvil assembly is also disclosed which includes a rib positioned proximally of a mounting projection. The rib is positioned to align the mounting projection with associated engagement structure of the anvil assembly.