UTI diagnosis

See NICE 224 (2022).

Classic symptoms – dysuria, frequency, new wetting, dark or cloudy or smelly urine.  Frank haematuria, loin pain.  Fever, shivering (rigors), history of UTI. 

Clean catch ideally, pad (commercial, not cotton wool balls or gauze) if clean catch unsuccessful. Else catheter.  Suprapubic aspiration is an option but needs ultrasound to confirm bladder full.

See Sofia method of urine collection.



Under 3 months – send for culture and microscopy. Urgent?

Microscopy interpretation is simply on basis of pyuria pos/neg, bacteria pos/neg.

Over 3/12, dipstick is standard. A positive dipstick urinalysis for BOTH leucocyte esterase (LE) and nitrite is specific, negative both is a good negative predictor. If dipstick positive for just one, not reliable either way. Metanalysis, Huicho Luis, PIDJ 2002;21:1-11. Previous metanalysis by Gorelick and Shaw (Peds 1999) concluded nitrite/LE tests superior to microscopy!

If nitrites and leucocytes positive, assume infection. Culture only if high risk for serious infection or recurrent UTI.

Nitrites only positive, treat but send culture.

Leucocytes only positive, send culture, treat if classic UTI symptoms or under 3yrs, else await result before treating.

Culture if high risk of serious illness, upper tract signs, poor response to treatment, recurrent UTI.

Most studies show that clean catch is equivalent to suprapubic aspiration (SPA); limited data on pad, nappy or bag specimens.

Uricol (Euron, Newcastle) urine pads. Check at 10 min intervals (discard after 30mins). Cost 18p each. Agrees with clean catch for gluc/ket/blood/nitrite (within 1 block ) but in study only 2 cases with leucocytes so ?reliable.

Health Technology Assessment (Winchester, England). 10(36):iii-iv, xi-xiii, 1-154, 2006 Oct.