A medical catheter includes an elongate catheter member defining a longitudinal axis, and a transverse axis transverse to the longitudinal axis, and having a proximal end and a distal end. The elongate catheter member includes an outer member and at least one longitudinal lumen within the outer member for passage of fluids. The outer member has an elongate opening therethrough in communication with the at least one longitudinal lumen and being spaced from the distal end and bound by wall portions of the outer member. The elongate opening permits fluids to pass between the at least one longitudinal lumen and locations external to the elongate catheter member, and defines a transverse dimension increasing from proximal to distal.