Does Pyuria Indicate Infection in Patients with Renal Colic?

In patients with obstructing kidney stones, urinary tract infection can be deadly, with rapidly progressive sepsis and death. Conventional wisdom is that some degree of pyuria is normal during acute renal colic, due to noninfectious inflammation. Investigators in a California emergency department prospectively evaluated performance of urinalysis results and other patient characteristics for predicting urine culture results in 360 patients with renal colic. Twenty eight patients (8%) had positive urine culture, defined as 1000 colony-forming units/mL of a single bacterial species.

Absence of pyuria was a very good predictor of a negative urine culture, in both febrile and afebrile patients (negative predictive value, 99%). But the presence of…