The present invention relates to an arterial flashback confirmation chamber. Generally, the confirmation chamber is used with a vascular access device to allow an operator to see active arterial flashback confirmation for a period of time that is long enough to permit the operator to properly place the cannula of the vascular access device within a patient's artery. In some instances, the confirmation chamber comprises a flashback compartment, means for prolonging active arterial flashback confirmation, and a vent. Some examples of suitable prolonging means comprise a flashback compartment with a relatively large internal volume, circuitous tubing, an absorbent material, an orifice and/or tubing with a smaller inner diameter than the inner diameter of the cannula, and the like. Where the vascular access device comprises a catheter assembly, the catheter assembly and confirmation camber are optionally used with a guide wire and/or a blood sensor.