Imaging in Haematuria Investigation

Metformin must be stopped for 48h prior to the study to avoid renal failure and lactic acidosis. Additional contraindications include asthma, pregnancy and sea food allergy. In many centres, IVU remains the main investigation for renal colic, but juniors often have difficulty interpreting the images. It certainly does not reliably diagnose an abdominal aortic aneurysm (AAA). It is more effective at diagnosing transitional cell carcinomas than US, but has a limited sensitivity in detecting small renal masses that are less than 2 cm in diameter.

CT

Non contrast CT is especially useful in stone disease. The study may well reveal the offending stone and quantify the degree of hydronephrosis. Ninety nine percent of stones are seen on non contrast helical CT, including urate and xanthine stones that are radiolucent on a kidney ureter bladder (KUB) film. Modern CT protocols can also approach the radiation dose of IVU. Contrast CT can determine whether cystic renal lesions are malignant or not [8,9]. Signs may also be evident of recent stone passage.

Most importantly, in an emergency department setting, the CT can identify or rule out other causes for the clinical picture, such as AAA. Renal carcinoma is increasing in incidence and, although still rare, may be found whilst investigating for renal stone disease.

Endoscopy

Endoscopy allows the urologist to rule out small mucosal lesions within the urinary tract. Flexible cystoscopy is often performed in a ward/day case environment prior to formal theatre and, if the urine is clear, the diagnostic accuracy is equivalent.

Diagnostic uncertainty or difficulty would involve resorting to rigid cystoscopy. Likewise, difficulty accessing the bladder with a flexible scope due to large prostate or stricture, for example, would be an indication for formal rigid cystoscopy.

Ultrasound

Ultrasound is excellent at visualising renal cystic masses and hydronephrosis. It can assess renal morphology, structure and vasculature and assess bladder wall and emptying. It is less sensitive than IVU in the diagnosis of uroepithelial tumours.

CT is more sensitive than ultrasound in detecting renal masses and tumours. Khadra estimated 43% of renal tumours would have been missed, if ultrasound alone had been used, in 1930 patients over 2.5 years [3]. Ultrasound sensitivity for detecting calculi is low at 37-64%. However, ultrasound is easily available and the safe investigation of choice in pregnancy.