RED FLAG FRIDAY: A NORMAL Urine Culture

Let's say that you treat a patient for a urinary tract infection and the initial UA which showed the following:

1+ protein, 1+ blood, 3+ LE, and POS nitrite

Then, several days later, the urine culture comes back normal:

NO GROWTH FOUND.

That result should not provoke rejoicing! It should cause some stress and worrying! Why? Because if the patient did not have a urinary tract infection, then what caused the 1+ blood in the initial UA? Could it be bladder cancer? Could it be renal cell carcinoma?

Whenever, I get a normal urine culture, the first thing that I do is to check the initial UA. If there is blood on the initial UA, I have the patient see me again to repeat another UA with a urine microscopy. If there are more than 3 RBC per high powered field, then I do a urology referral to work-up hematurea.