Upper, lower, atypical, recurrent – all have specific definitions;
Diagnosis is ideally by culture – minimum of 1.25 ml, pref 2.5ml of urine in a 7ml red top boric acid container. White top only acceptable if received at lab on same day or day before, within hospital. Collection method important, ideally clean catch.
But given delay in getting culture result, urinalysis more practical, if less sensitive/specific. Nitrites have high positive predictive value so treatment usually started pending culture. Microscopy (for white cells and bacteria) is routinely done in infants under 3 months but needs to be requested between 3 months and 3 years. Greater than 100 wcc or 1000 organisms considered “numerous”, above 40 wcc or 500 organisms “moderate”.