Should Contrast CT Urography Replace Non-Contrast CT as an Investigation for Ureteric Colic in the Emergency Department in those Aged 65 and Over?

Patients presenting with ureteric colic to emergency departments are usually investigated with a non-contrast CT scan (CT KUB) because urolithiasis is the most common cause of ureteric colic and a non-contrast CT scan has high sensitivity and specificity for diagnosing urolithiasis. Furthermore, non-contrast scans allow for a rapid and economical method of diagnosing stones and other emergency conditions like abdominal aneurysms.

However, nearly a third of elderly patients with upper tract TCC have a history of colicky pains with either visible or persistent non-visible haematuria. A CT urogram is the recommended test for these tumours rather than a non-contrast CT. Thus, we were concerned that we might be missing upper tract TCC in the elderly who present to emergency departments with colic and haematuria and had a non-contrast CT scan.

We investigated whether a CT KUB or a CT urogram is the appropriate test in patients aged 65 and over who presented with colic and microscopic haematuria over a 34 month period to the emergency department of a busy district general hospital in London. Out of 485 such patients who had a CT KUB, the diagnosis was uncertain in only 33 patients. These 33 patients went on to have a CT urogram.

In our study, CT urography identified only one upper tract CT that had been missed by CT KUB, representing 0.2% of our study cohort. CT urography corroborated the findings of a ureteric tumour in one patient and helped exclude upper tract TCC in two others. Interestingly, though CT KUB diagnosed most non-stone conditions, we found discordance in diagnosis between the two tests in about half the 33 patients who had both investigations. This discordance is probably due to the limitations of the sensitivity of a non-contrast study as compared to a CT urogram. Despite the discordance, the benefit of doing a CT urogram in these patients is low. The advantages are outweighed by the costs, the higher radiation dosage, contrast-induced risks and the resources and time spent rapidly reaching a working diagnosis in a rushed emergency department. Despite study limitations, our study validates the current investigation protocol of a CT KUB as the emergency investigation of choice for the elderly with colic and haematuria.

Written by: Deepak Batura, Department of Urology, London North West University Healthcare NHS Trust, Watford Road Harrow, London, UK

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