a multi - lumen catheter for independent delivery and withdrawal of fluids having an improved leading end to minimize stasis and an improved coupling for connection to externally located infusion and withdrawal tubes . the improved leading end has an ellipsoidally shaped tip with a smooth , uninterrupted surface and , in close proximity to the tip , a port or ports evenly spaced along the length of each lumen in staggered relation between each lumen . the improved coupling is a generally l - shaped , implantable transition device bonded to a percutaneous access device . the overall conformation of the multi - lumen catheter may be either a &# 34 ; u - shape &# 34 ; or an upright &# 34 ; z - shape .&# 34 ; externally located infusion and withdrawal tubes are in fluid connection with an epidermal end of the transition device and a multi - lumen tube fits snugly over nipples at a subcutaneous end of the transition device .