A tissue resecting instrument includes a drive assembly coupled to an inner cutting shaft and configured to drive translation and/or rotation of the inner cutting shaft, a trigger coupled to the drive assembly and configured for manual actuation to drive the drive assembly, a vacuum generator configured to generate vacuum to suction cut tissue through the inner cutting shaft and into the vacuum generator, and a tissue collection cartridge configured to engage the housing. The tissue collection cartridge defines a port configured to communicate with the vacuum generator such that the vacuum generator urges cut tissue from the vacuum generator through the port into the tissue collection cartridge. An auxiliary vacuum source is configured to selectively provide additional vacuum to increase suctioning of cut tissue through the inner cutting shaft and into the vacuum generator.