I am 34 year old female, married with 4 kids. I just got over having a UTI. I was one a 3 day dose of Cipro, still had a trace of red and white blood cells, so 3 more days of Septra. Since I still had a small trace of red blood cells the second time I went in the doctor wants to do an ultrasound. (3 years ago I had a kidney stone). I am a worrier, he does not seemed overly concerend, just cautious. Also, by urine sample was sent out for testing and came back negative. Should I be worried that he wants to do an ultrasound, or does this seem routine. Forgot to mention, back in the fall of 2009, had my yearly physical, urine test was negative for infection, but had a small trace of red blood cells. Just had a CBC done in May and all is good with that. Thank you in advance for your time and consideration.