Under 49 CFR Part 40, when a donor cannot provide at least 45 mL of urine, the collector documents a "shy bladder" situation. The donor is given up to 3 hours and 40 ounces of fluids to attempt another collection. If still unable, the employer must refer the donor for a medical evaluation within 5 business days. A licensed physician determines whether there is a legitimate physiological or pre-existing psychological condition that prevents the donor from providing. If no valid medical explanation exists, the MRO reports the test as a refusal to test. The same process applies to "shy lung" situations where an employee cannot provide an adequate breath sample for alcohol testing.