A method of preventing inadvertent interconnection between a first medical system and a second medical system utilizes a luer fitting connector/adapter that acts as a modified-to-standard size converter piece. The adapter may complete a fluid tight medical system. The adapter may have one end having at least one non-standard sized luer fitting dimension. The non-standard end of the adapter may sealingly interconnect with a luer fitting member having a corresponding non-standard sized dimension. As a result, the adapter and luer fitting member may be directly interconnected with one another while remaining incompatible with standard sized luer fittings. Using the adapter may facilitate preventing the inadvertent direct interconnection of standard sized luer fitting members intended for different purposes, such as the delivery of a feed paste or a medication to a desired location within a patient. The adapter may be directly or indirectly interconnected with a syringe nozzle to facilitate flushing the medical system or a portion thereof.