A stopcock, comprising a housing element defining a central bore and at least first, second and third ports; and a handle element which is selectably positionable relative to the housing element; at least one of the housing element and the handle element defining: a first fluid flow passageway communicating between two of the at least first, second and third ports; a second fluid flow passageway communicating between at least two of the at least first, second and third ports, and a fluid flow guide associated with the second fluid flow passageway, the fluid flow guide extending radially towards an inner facing wall of the central bore.