A surgical instrument (100) includes first and second shaft members (110, 120) defining proximal and distal end portions (112a, 122a, 112b, 122b) and including handles (114, 124) at the proximal end portions (112a, 122a) thereof. A pivot member (130) couples the distal end portions (112b, 122b) with a gap (G) defined therebetween proximally of the pivot member (130). First and second jaw members (210, 220) extend distally from the shaft members (110,120), distally of the pivot member (130). A lockout bar (160, 560, 660, 760) is movable between an unlocked position, withdrawn from the gap (G), and a locked position, disposed within the gap (G). The handles (114, 124) are pivotable between spaced-apart and approximated positions to pivot the jaw members (210, 220) between open and closed positions. The handles (114, 124) are yawable between the approximated position and a yawed position to yaw the jaw members (210, 220) between the closed position and a cutting position. The gap (G) provides clearance to permit yawing such that, when the lockout bar (160, 560, 660, 760) is disposed in the locked position, yawing of the handles (114, 124) is inhibited.