One aspect of the invention provides a trocar, comprising: a central cylinder defining a central channel and having a distal end configured for insertion within a body cavity of a subject; one or more outlets located within the central cylinder, wherein the one or more outlets are configured to dispense a liquid when an endoscope is withdrawn from a distally extended position within the central channel of the trocar to a position proximate to the one or more outlets, the one or more outlets having a shape or size sufficient to generate sufficient flow to reach a center of the central cylinder and clean a lens of the endoscope; a sensor configured to detect when a distal end of the endoscope has been withdrawn to the position proximate to the one or more outlets; and a controller in communication with the sensor, the controller configured to control the flow to the one or more outlets to expel the liquid from the one or more outlets when the distal end of the endoscope is proximate to the one or more outlets.