An adapter for a syringe includes a base portion having an insertion hole and a flange portion extending laterally outwardly from the base portion. A longitudinal axis of the flange portion extends from a first distal end to an opposing second distal end. A first distance measured from a geometric center of the insertion hole to the first distal end of the flange portion is less than a second distance measured from the geometric center of the insertion hole to the second distal end. The first distance defines a first section of the flange portion and the second distance defines a second section of the flange portion. The first section has a cross-sectional shape that is one of at least slightly concave and at least slightly convex and the second section has a cross-sectional shape that is the other of at least slightly convex and at least slightly concave.
