What is the sterile method for urine collection?

• A. Cystocentesis
• B. Free-catch
• C. Catheterization
• D. Bag sample

Answer: (A)

To obtain a truly sterile urine sample, collect directly from the bladder while avoiding contact with the urethral and external genitalia. This is done with cystocentesis, using a sterile needle inserted through the abdominal wall into the bladder under aseptic technique. Because the urine is drawn straight from the bladder and bypasses the lower urinary tract and external tissues, it remains free of contaminants that come from the skin, genital tract, or environment—making it the best choice for culture and sensitivity testing.

Free-catch urine is voided and can pick up bacteria and debris from the skin and genital area, so it isn’t sterile. Catheterization can be performed aseptically, but it still traverses the urethra and can introduce organisms from the distal tract, making the sample less reliably sterile than cystocentesis. Bag samples are highly prone to contamination from skin and fur and are the least reliable for culture.