An adaptor comprises a plate having upper and lower surfaces, and oppositely disposed side edges therebetween. A luer mating structure is associated with the plate upper surface. A blunt cannula is associated with the lower surface. The blunt cannula has a proximal portion extending from the plate lower surface and a distal portion extending from the proximal portion to a tip end. A pair of generally flat guide walls extends from the plate side edges to either side of the blunt cannula.