A catheter includes an elongate body defining a continuous enclosed liquid flow channel, at least a portion of the liquid flow channel including a modification having a first surface and a second surface and an included volume between the first surface and the second surface, at least a portion of the included volume defining an elongated air flow channel, at least a portion of the first surface and the second surface coated with a hydrophobic (e.g., superhydrophobic) material. The catheter can be a urinary catheter (e.g., a urine drainage tube connected to a urine collection bag). Methods of flowing liquid through a catheter and of catheterizing a patient are encompassed.
