Renal colic: a prospective evaluation of non-enhanced spiral CT versus intravenous pyelography

Abstract

The aim of this study was to compare non-enhanced spiral CT (NECT) and intravenous pyelography (IVP) in patients with suspected acute renal colic. Two-hundred patients presenting to the Emergency Department with suspected acute renal colic were randomized into groups undergoing NECT or IVP. The main outcome measures were diagnostic utility, incidence of alternative diagnoses, requirement for further imaging, length of hospital stay, urological intervention rates, radiation dosage and costs. Non-enhanced spiral CT was better than IVP in making a definitive diagnosis of ureteric calculus or of recent calculus passage (65/102 or 66% vs 42/98 or 41%; P = 0.003). Calculi were missed in two patients in the IVP group. Two patients in each group had alternative diagnoses by initial imaging. There was no difference in the length of hospital stay or intervention rate. More plain X-rays during admission and more IVPs during follow up were performed in the NECT group. Effective radiation dosages were 2.97 mSv (IVP) and up to 5 mSv (NECT). Non-enhanced spiral CT provided greater diagnostic utility in this randomized comparison but no difference in measured outcomes. The incidence of alternative diagnoses was low, probably due to patient selection. Financial costs for each modality are comparable in a public tertiary hospital. Radiation dosages are higher for NECT and, for this reason, it might be appropriate to consider limiting NECT use to patients who have do not have classical symptoms of renal colic, to older patients and those with a contraindication to the administration of intravenous contrast media.