A surgical apparatus used in an ostomy procedure includes an introducer configured for atraumatic insertion in a tissue opening and a dilator. The dilator includes an elongate body and an extension movably coupled to the elongate body. A distal portion of the elongate body is disposed within and axially movable relative to the introducer between first and second positions. The extension is configured to move from a retracted state to an expanded state in response to movement of the dilator relative to the introducer from the first position to the second position. In the retracted state, the extension is disposed within the introducer, and in the expanded state the extension projects laterally outward from the distal portion of the elongate body.