A medical device includes a sheath having a proximal end and a distal end, the sheath having an opening at both the proximal end and the distal end, and a removable dilator having a distal end and a proximal end, the dilator having at least one blood detector disposed on a tapered portion of the distal end of the dilator, the dilator positionable within the sheath such that the tapered portion of the distal end of the dilator extends through the opening in the distal end of the sheath, the proximal end of the dilator extends through the opening in the proximal end of the sheath, and at least a portion of the at least one blood detector is adjacent to the distal end of the sheath.