Abstract: A catheter with several independent lumens extending longitudinally through the catheter for accepting probes and for introducing fluid through the catheter and into a body cavity is disclosed. The catheter outer body has a cross-sectional maximum outer dimension. The first lumen is circular in cross-section, and has a cross-sectional dimension of approximately half the maximum outer dimension of the catheter body. The first lumen is capable of accepting various probes, as well as allowing simultaneous fluid flow through the lumen. The second lumen is crescent-shaped in cross-section and occupies at least a quarter of an arc around the cross-section of the catheter body. The large cross-section of the second lumen allows for a high fluid flow rate through the lumen. The third lumen allows for inflation of an inflation balloon (when present), and the fourth lumen allows for the passing of a portion of an instrument along the length of the lumen.