a catheter apparatus is provided for reducing blood clotting in connection with hemodialysis treatment . the catheter apparatus can comprise a first conduit defining an arterial lumen and a second conduit defining a venous lumen . large staggered apertures can be provided in side walls of the conduits with at least one of the apertures having a cross - sectional area equal or greater than a cross - sectional area of one of the lumens . the catheter apparatus can further include first and second removable obturators adapted for axial insertion into the conduits and for occluding the apertures while so inserted . advantageously , the obturators can wipe the apertures during removal , causing blood clots incident on the apertures to be dislodged from the apertures . related methods for using the catheter apparatus in performing hemodialysis treatment are also provided .