Urine dipstick vs. microscopic urinalysis in the evaluation of abdominal trauma.

This study was designed to assess the accuracy of the urine dipstick and its ability to predict injury to the urinary tract when compared to routine urinalysis: 1,485 patients had dipstick and microscopic urinalysis performed as part of their evaluation for blunt and penetrating trauma. Dipstick analysis was recorded as either positive or negative. Microhematuria was defined as greater than 0-1 RBC/HPF on microscopic analysis. Blunt trauma accounted for 1,347 (91%) of the patients and penetrating injuries accounted for 138 cases (9%): 1,209 (81.4%) of the specimens were dipstick negative, and 276 (18.6%) were dipstick positive. False negative results, consisting of a negative dipstick reading and greater than 1 RBC/HPF on microscopic analysis occurred in 100 (6.9%) of the cases. False positive dipstick readings occurred in 64 (4.3%) of the patients. There were no cases of a missed injury in the group of 100 false negatives. Cost savings by conversion to the use of dipsticks would have saved our institution about $63,000 per year. It is concluded that the urinary dipstick is a safe, accurate, and reliable screening test for the presence or absence of hematuria in patients sustaining either blunt or penetrating abdominal trauma.