Objectives & Background In 2008 and 2009 the British Association of Urological Surgeons and the Royal College of Radiologists issued recommendations that non contrast CT scanning should be the first line imaging modality for the diagnosis of renal calculi in the acute setting. More than 6 years later we hypothesise that this has led to a large increase in CT scans and thus radiation exposure, without demonstrating and increased need for surgical intervention.

Methods All CT scans of the abdomen or Kidneys, ureters and bladder ordered by the ED from 2008 to 2013 were collated via the Picture Archiving and Communication System. This data was analysed and all cases not relating to investigation of urolithiasis were disregarded. A final list was interrogated for gender, age and previous diagnosis of stones. Annual attendance rates to the ED and the number of litholopaxy procedures were also collected.

Results 1208 CT scans were performed to diagnose renal colic in this 6 year period. The number of scans performed annually rose from 51 in 2008 to 252 in 2013. 35% were women and of those women a median of 70% annually were under the age of 50. 23% of patients had previously confirmed urolithiasis. Of those a median of 64% annually were under the age of 50. Despite ED attendances rising in this period by 13.5%, the proportion of patients scanned for stones disease rose from 0.05% to 0.2%. The number of litholopaxy decreased from five to one.

Conclusion These results show that despite an increased proportion of patients receiving a CT scan since 2008, the number of patients requiring intervention has actually decreased. Additionally, repeated scanning of those under the age of may be causing significant cumulative radiation exposures. We propose a prospective trial is needed to use more appropriate imaging for this group of patients. In addition, refinement of the clinical question posed by patients with presumed urolithiasis might lead to the use of a different imaging modality such as ultrasound.