An introducer sheath includes a tubular body portion having a proximal region and a distal region, and defines an internal lumen configured and dimensioned to slidably receive a catheter. A penetrating portion at a distal end of the tubular body has a first tapered configuration to enlarge an opening in a body tissue during distal advancement of the introducer sheath through the body tissue and a second expanded configuration to enable the passage of a distal end portion of a catheter through the penetrating portion.