A peripheral intravascular catheter assembly comprising a tubular introducer needle and an adapter connected to the proximal end of the light guide. An introducer needle comprises a connection hub and a needle member. The needle member has a lumen, a distal end and a proximal end. The assembly can include a cannula tubing surrounding at least a portion of the needle member, with at least one light source and with an electronic module, configured to power the light source. The light guide has a distal end and a proximal end and extends along the lumen of the needle member. The adapter may be connected to the electronic module to the connection hub of the introducer needle so that light emitted by the light source is capable of entering the light guide, but blood flowing through the lumen of the needle member is prevented from contacting the light source.