Raised white cell count in renal colic: Is there a role for antibiotics?

To determine the use of antibiotics in patients with renal colic and an elevated white cell count (WCC) in the absence of other features of infection.

A retrospective audit of patients presenting to an emergency department with renal colic caused by a solitary ureteric stone over a 6 month period.

Student's t-test.

Fifty patients met the inclusion criteria for this study. In 42 patients (84%) the urinalysis showed hematuria only and all urine culture results were negative for microbial growth. The mean WCC was 11.5 × 10(9) (4-22.1) and was raised in 34 patients (80.9%). The mean neutrophil count was 8.75 × 10(9)/L (2.3-18.6) and C-reactive protein (CRP) 15.9 (1-192). Antibiotics were commenced in 34 patients (80.9%) based solely on the raised WCC. In eight patients (16%) there were leucocytes and/or nitrites on urinalysis and all urine cultures were positive for growth (coliforms in five, streptococcus in two and candida in one specimen). The mean WCC was 10.5 × 10(9)/L (7.7-16.5) and was raised in four patients. The mean neutrophil count was 8.4 × 10(9)/L (4.9-15.2) and CRP 40.79 (3-86). One patient had pyrexia. All eight patients were commenced on antibiotics based on the WCC and/or urinalysis result.

Over three-quarters of the patients (80.9%) in this study who presented with renal colic were unjustifiably commenced on antibiotics based solely on an elevated WCC. Antibiotic use in renal colic should be reserved for when there are features of sepsis or the urinalysis is positive. Further work is required to determine the significance of the observed results and the threshold for starting antibiotics.