A surgical instrument includes a handle assembly, a surgical loading unit, and an adapter assembly coupled therebetween. The adapter assembly includes a housing, an elongated body, a switch assembly, and a switch actuator. The elongated body extends distally from the housing and is configured to be coupled to the surgical loading unit. The switch assembly is disposed within the housing and configured to communicate that the surgical loading unit is coupled to the elongated body. The switch assembly includes a substrate, a switch mounted on the substrate, and at least one wire coupled to the substrate. The switch actuator is movably disposed within the housing and configured to actuate the switch upon engagement of the surgical loading unit with the elongated body.