A catheter (100) has an elongated tubular body (102) and a septum (108). The elongated tubular body defines a longitudinal axis and includes a first wall (104) defining a first lumen (104a) and a second wall (106) defining a second lumen (106a). The first lumen and the second lumen communicate with first (104b) and second distal openings (106b), respectively. The septum separates the first and second lumens. One or both of the first and second walls includes a side opening (110a, 110b). The side opening is fluid communication with one of the first and second lumens. The side opening has an external aperture (112) and an internal aperture (114). The internal aperture is smaller in dimension than the external aperture.