Load sensor for circular surgical stapler

A surgical circular stapler has a handle assembly, a shaft assembly, a stapling head assembly, and an anvil. Firing the stapler causes the stapling head assembly to drive a plurality of staples in a circular array to secure two lumens of tissue together. The stapling head assembly may further drive a blade to sever any excess tissue interior of the circular array of staples. The stapler further includes one or more sensors that detect the degree to which the anvil is uniformly loaded when compressing tissue prior to firing the stapler. The one or more sensors can provide signals to a processor with various logic rules that can be used to signal to the user whether uniform loading is achieved. In some instances, the signal may be used in an automated fashion to determine if a uniform loading precondition is satisfied such that firing the stapler is enabled.