A colonic lavage catheter includes a head attached at an end of a suction tube and having both rearward and lateral fluid discharge openings. A pair of tubes extend along the suction tube with their ends attached to the head to place the rearward and lateral fluid discharge openings in fluid communication with a source of pressurized fluid. The suction tube includes a plurality of suction orifices through the outer wall along its length proximate the catheter head. A cleaning process may be performed by inserting the catheter head into the colon and then discharging fluid through the rearward openings to advance the catheter. At points along the colon, pressurized fluid may be discharged through the lateral discharge openings to lavage the adjacent walls of the colon, with suction being applied to draw the dislodged material into the suction tube through the suction orifices.