How can I differentiate between a urinary tract infection and other conditions with similar symptoms in adult patients?

To differentiate a urinary tract infection (UTI) from other conditions with similar symptoms in adult patients, focus on the presence of specific urinary symptoms such as dysuria (painful urination), increased frequency, new onset of urgency, and visible changes in urine like cloudiness, foul smell, or haematuria. These symptoms increase the likelihood of a UTI ¹. Systemic signs such as fever, loin or suprapubic tenderness also support a UTI diagnosis ¹.

Conversely, the absence of dysuria, presence of symptoms like nappy rash (in children), respiratory symptoms, or fever with a known alternative cause decrease the likelihood of UTI and suggest other diagnoses should be considered ¹. In adults, similar principles apply: if urinary symptoms are absent or if symptoms point to other systems (e.g., respiratory or gynecological), alternative diagnoses should be explored.

Urine dipstick testing for leukocyte esterase and nitrites is a useful initial diagnostic tool; a positive result supports UTI, while both negative results make UTI unlikely, guiding against antibiotic treatment ¹. However, clinical judgment remains essential, as false negatives can occur, and symptoms should guide testing decisions ¹.

In adult women, clinical prediction rules from literature (Bent et al., 2002) emphasize that the combination of dysuria, frequency, and absence of vaginal discharge or irritation strongly predicts uncomplicated UTI, helping to differentiate from other causes such as vaginitis or sexually transmitted infections (Bent et al., 2002).

When systemic symptoms like high fever or flank pain are present, consider upper UTI (pyelonephritis), which requires more urgent management ¹. If symptoms are localized to the lower urinary tract without systemic signs, lower UTI (cystitis) is more likely ¹.

In summary, differentiation relies on a thorough symptom assessment focusing on urinary and systemic signs, supported by urine dipstick testing, and consideration of alternative diagnoses when symptoms do not align with typical UTI presentations. Clinical prediction rules from adult studies can further refine diagnostic accuracy in primary care ¹ (Bent et al., 2002).