An adapter (142) for connecting a syringe to a catheter, having a tapered recess (143) to receive an outlet from a syringe at one end and a male connector having recessed channels (144) and raised ribs (145) at the other end. A one-way valve fitting (146) having a shape complimentary to the channels and ribs of an adapter is also provided, preferably fitted to the instillation port of a catheter, and especially a urinary catheter.
