Diagnosis

The current approach for diagnosing patients with suspected UTI is clinical diagnosis based on presenting complaint and medical history.

• Take a detailed history to inform a differential diagnosis and exclude other causes, for example a sexually-transmitted disease that may present with urinary symptoms alone.
• In women of childbearing age consider if the patient could be pregnant as this will influence management.

Recurrent UTI

Recurrent UTI is defined as repeated UTI within a given frequency.  Evidence - See section 1.1.5 in full guideline.

There therefore is no difference in the diagnostic criteria used when managing recurrent UTI.

Consider other causes for recurrent symptoms such as interstitial cystitis, bladder pain syndrome, renal stone or underlying malignancy (particularly in the context of haematuria).

Recommendation
Do not diagnose a UTI in the presence of a combination of new onset vaginal discharge or irritation and urinary symptoms (dysuria, frequency, urgency, visible haematuria or nocturia).

Good practice point
In making a differential diagnosis it is important to investigate for urethritis and other causes of symptoms to rule out conditions that present in similar ways to uncomplicated UTI.

Recommendation
Do not confirm the diagnosis of a UTI in the presence of a single urinary symptom (dysuria, frequency, urgency, visible haematuria or nocturia).

Good practice point
Advise the patient that a UTI cannot be confirmed based on a single urinary symptom and to return if the symptom fails to improve or worsens.

Recommendation
Diagnose a UTI in the presence of two or more urinary symptoms (dysuria, frequency, urgency, visible haematuria or nocturia) and a positive dipstick test result for nitrite.

Good practice point
Before carrying out a dipstick test urine should be retained in the bladder for at least four hours to allow conversion of urinary nitrates to nitrite by pathogens. Shorter incubation times may lead to false negative results.

Good practice point
On diagnosis of UTI in the presence of two or more urinary symptoms and a positive dipstick test result for nitrite, a urine specimen should only be sent for culture if the patient has a history of resistant urinary isolates, has taken any antibiotics in the past six months or fails to respond to empirical antibiotics.

Good practice point
Consider sending a urine specimen for culture to inform the diagnosis in patients who present with suspected UTI and two or more urinary symptoms and a negative dipstick test result for nitrite.

Diagnostic tests

Microscopy, culture and antibiotic sensitivity analysis of a midstream, clean-catch urine specimen is used to confirm the presence and identity of bacteria causing urinary infections.⁵⁰

The European Association of Urology guideline for urological infection states that uncomplicated LUTI can be diagnosed based on:

• A history of urinary symptoms and absence of vaginal discharge.
• Dipstick analysis can increase the diagnostic accuracy when diagnosis is unclear.

Urine culture and sensitivity analysis is not routinely recommended other than in patients with atypical symptoms, as well as those who fail to respond to appropriate antimicrobial therapy.²⁹

The results of these tests are typically available within 24–72 hours after the microbiology laboratory receives the specimen. Symptoms may therefore resolve before the result can influence diagnosis or management.

Clinicians can perform a urine dipstick test to confirm the presence of bacteria, which, in the presence of signs and symptoms, may be suggestive of a UTI with 30–40% sensitivity and up to 95-98% specificity based on positive urine nitrites.⁵¹

The test does not specify the pathogen(s) causing the infection or the antibiotic sensitivities.

Three meta-analyses were identified which investigated pretest probabilities, post-test probabilities or a combination of both to predict UTI in women.^51-53

Symptoms

See section 3.1.2 in full guideline.

Dipstick testing

See section 3.1.3 in full guideline.