Emergency Provider's Ability to Stratify Risk of Renal Calculi Prior to CT Scan Confirmation
Jasmine Pierre, M.D., Nicole Nadel, D.O.
Objective: The study purpose was to determine how well emergency medicine providers are able to predict the likelihood of renal calculi based on clinical presentation and urinalysis prior to confirmation by unenhanced computed tomography (CT) scan.
Methods: We enrolled a consecutive cohort of adults presenting to the ED of an urban teaching hospital whose clinical presentation was suspicious enough for renal colic to warrant confirmation by CT imaging during a two month period. Patients were enrolled when an order for CT without contrast was placed to rule out renal calculi, at which time the EM provider (attending, resident, or physician assistant) also predicted the probability of the presumed diagnosis. The provider’s predications were stratified into 5 risk categories (0-20%, 20-40%, 40-60%, 60-80%, 80-100%).
Results: 148 adult patients were enrolled during the study period. 58 (40%) patients were not found to have CT confirmed renal calculi. 78 (53%) patients were found to have radiographic evidence of a stone. 11 (7%) patients were found to have CT evidence of renal calculi, without the actual presence of a stone, and were excluded from the study. 1 patient was found to have an alternative diagnosis of diverticulitis and was excluded. When EM providers predicted there was 0-20% chance o f a renal calculi, our study showed that 20% (2/10) had a definite stone. When a 20-40% chance was predicted, 36% (5/14) patients had a definite stone. When a 40-60% chance was predicted, 34% (11/32) patients had a definite stone. When a 60-80% chance was predicted, 69% (29/42) patients had a definite stone. When a 80-100% chance was predicted, 82% (31/38) patients had a definite stone.
Conclusion: Emergency providers ordering CT imaging on patients with suspected renal calculi are able to accurately predict the likelihood of the diagnosis.