An apparatus to control blood flow through an intravenous catheter in accordance with the present invention may include a substantially resilient helical outer shell and an inner valve portion formed therein. The inner valve portion may be configured to open upon compressing the substantially resilient helical outer shell. In some embodiments, the inner valve portion may include mating portions that substantially align to provide fluid leakage therebetween. Compressing the substantially resilient helical outer shell by, for example, inserting a Luer device into a catheter adapter containing the substantially resilient outer shell, may cause the mating portions to misalign, thereby creating a fluid path.