Abstract: A catheter to be passed through the nasopharynx and into the trachea without contamination of the catheter lumen for obtaining uncontaminated sputum specimens. The catheter lumen is sealed to prevent entry of contaminants by the provision of a length of flexible, expandable tubing placed over and attached to the distal end of the catheter. The flexible tubing is rolled-up over a portion of its length and inverted into the unrolled portion, with the unrolled portion forming a cuff encircling the rolled-up portion to hold the rolled portion. A syringe pump connected to the opposite end of the catheter introduces fluid under pressure into the lumen of the catheter to expand the cuff and urge the rolled-up portion of the tubing from the cuff, and to unroll the tubing, whereby the lumen of the catheter is unsealed. An inner catheter is inserted into the lumen of the outer catheter and advanced therethrough and out the end beyond the tubing for performing aspiration.