An instrument for facilitating insertion of a catheter through a subcutaneous tunnel includes a tunneling stylet defining a longitudinal axis and having leading and trailing ends, a bifurcated segment adjacent the leading end of the tunneling stylet and a releasable cover releasably mountable to the leading end of the tunneling stylet to substantially enclose the bifurcated segment. The bifurcated segment includes first and second elements adapted for reception within respective lumens of a catheter.