Circular stapler for hemorrhoidal surgery

A circular stapling instrument adapted for the removal of internal hemorrhoids, said instrument comprising:

• a handle;
• a shaft extending from said handle;
• a stapling head assembly extending from said shaft, said assembly having:
• a) a substantially hollow casing having an exterior casing surface,
• b) a substantially hollow staple driver received in said casing for movement therein between a prefired position and a fired position,
• c) an annular blade mounted within said staple driver at a distal end of said staple driver,
• d) an elongated interior drive shaft reciprocable within said staple driver and said annular blade;
• an anvil assembly having an anvil shaft attached to said elongated interior drive shaft, said anvil assembly movable in response to reciprocation of said interior drive shaft from an open position spaced from said casing to a closed position adjacent to said casing, and when said anvil assembly is in the open position, said staple driver and said interior drive shaft define a first inner chamber therebetween, and said annular blade and said interior drive shaft define a second inner chamber therebetween, said second inner chamber communicating with said first inner chamber;
• and
• wherein when said staple driver is in the prefired position, a substantially unobstructed passageway is provided, said passageway extending from said exterior casing surface of said casing into said first and second inner chambers for insertion and withdrawal of a surgical instrument into and from said first and second inner chambers, said passageway being substantially parallel to said interior drive shaft.