A reversible vasectomy device includes a first and a second connector piece for attachment to the severed ends of the vas deferens. Each connector piece has an outer vas deferens attaching end, an opposite inner end, and a passage from the outer to the inner end. A midpiece has end portions that are connectable to the inner ends of the connector pieces, a passage in one end portion and a vent from the passage to an exterior surface. When the connector pieces are connected to the end portions, the passage in one of the connector pieces is in fluid communication with the vent, but is not in fluid communication with the passage in the other connector piece.