Surgical staplers and methods of their use are provided. In one embodiment, a surgical stapler includes a tubular shaft having a proximal end and a distal end, a handle extending from the proximal end of the tubular shaft, a head assembly extending from the distal end of the tubular shaft, and an insertion guide configured to extend through the head assembly. The insertion guide includes an expandable member configured to move between a collapsed configuration and an expanded configuration.
