A specimen trap has first and second fluid chambers, an inlet tube for introducing fluid from the body into the first chamber, the walls of the trap defining a port substantially larger than the flow cross-section of the inlet tube for flow of fluid from the first chamber to the second chamber, and an outlet tube for removing fluid from the second chamber. The outlet tube projects into the second chamber and terminates therewithin at a position spaced from the walls of the chamber. When the cham...