Hoover, a canine patient, was diagnosed with a urinary tract infection 2 weeks earlier and was placed on a course of amoxicillin. The veterinarian asked that he return for a recheck to ensure the infection has resolved. The collection method of choice in this patient would be

• A. Free catch
• B. Cystocentesis
• C. Catheterization
• D. Manual expression

Answer: (B)

For confirming that a urinary tract infection has truly resolved, you want a urine sample that is as free from contamination as possible. Cystocentesis accomplishes this by drawing urine directly from the bladder through the abdominal wall, bypassing the urethra and external genitalia. This yields a sterile sample ideal for culture and sensitivity testing, so you can accurately determine whether bacteria are still present after treatment.

Free catch samples are easy but commonly contaminated by bacteria from the skin, genital tract, or environment, which can lead to misleading results when you’re trying to decide if the infection is gone. Catheterization and manual expression can also introduce contaminants and carry additional risks, whereas cystocentesis provides the cleanest sample for assessing true infection status.

In this case, two weeks after starting antibiotics, the best method to verify resolution is to obtain a cystocentesis sample for culture and urinalysis to ensure the infection has cleared.