A heat transfer pad includes a bladder and a pad port. The bladder has an outside perimeter, an inner face and an outer face enclosing a bladder interior. The pad port has a tubing segment with a proximal end which extends through the outside perimeter of the bladder into the bladder interior. A port seal is formed by bonding the inner and outer faces of the bladder to the proximal end of the tubing segment at a port bond point distal to the outside perimeter of the bladder in the bladder interior. The proximal end of the tubing segment is maintained unbonded to the inner and outer faces of the bladder between the port seal and the outside perimeter of the bladder, thereby defining a strain relief section of the bladder which resists occlusion of the pad port.