Urine cytology appears to have no diagnostic benefit in the investigation of low-risk patients with non-visible haematuria.

A total of 200 patients attending a haematuria clinic in Quebec, Canada were studied. These patients were considered to be low risk for urothelial cancer as they were non-smokers, with no significant occupational risk factors, history of previous malignancies or radiotherapy or cyclophosphamide exposure.

All patients had a flexible cystoscopy, upper tract imaging and urine cytology. No patients had positive urine cytology, 23 (11.5%) had atypical cytology and 177 (88.5%) had negative cytology. Of the 200 patients assessed, eight (4%) were found to have low-grade urothelial tumours of the bladder, consistent with previously published case series which tend to estimate the overall risk of malignancy in non-visible haematuria as 4-5%.

Of these eight patients, four had negative cytology and four had atypical cytology results. No high-grade, muscle invasive or upper tract tumours were identified.

Approximately 15% of patients with atypical cytology were found to have tumours. When atypical cytology was analysed as a positive result, the sensitivity, specificity, positive predictive value and negative predictive value of the test were 50%, 90%, 17% and 98% respectively.

Urine cytology is of uncertain use, particularly in a primary care setting. The assessment of patients with non-visible haematuria has long been controversial. There is a high prevalence of the condition in the community and relatively low pick up rates of significant pathology on investigation. Traditionally, assessment in secondary care has consisted of a flexible cystoscopy, upper tract imaging (either by ultrasound, IVU or CT urogram), with or without urine cytology.

The use of urine cytology in non-visible haematuria is currently recommended by the American Urological Association guidelines, but the British Association of Urological Surgeons/Renal Association guidelines in the UK do not recommend the routine use of cytology. While this study is small and can only be of limited use in determining the correct management strategy for this condition, it would appear to support the British guidelines. GPs should therefore observe these guidelines, with initial investigation in primary care of MSU to exclude infection plus measurement of renal function, albumin:creatinine ratio and blood pressure, followed by referral to secondary care for further investigation.

It is unnecessary, therefore, for GPs to arrange urine cytology in patients with non-visible haematuria as the result is unlikely to affect clinical management.

Dr Jonathan Rees