Are urine dipsticks reliable indicators of hematuria in blunt trauma patients?

Dipstick results in patients with blunt trauma have not been demonstrated to be predictive of the amount of microscopic hematuria. Our study examined the relationship between dipstick results and the degree of microscopic hematuria in 185 patients admitted to our emergency department following blunt trauma. Urine samples of 169 were dipsticked; the remaining 16 were grossly bloody. A wide range of microscopic hematuria results was obtained for each dipstick value. Of the 80 patients with negative dipsticks, 15 (18.7%) actually had microscopic hematuria. Conversely in 16 of 32 patients (50%) with a "trace" positive dipstick value, no microscopic hematuria was present. Similarly the dipstick value of 1+ had three of 14 (21%) false positives. False positives were recorded seven of 26 times (27%) for 2+, and three of 17 times (18%) for 3+ dipstick readings. We conclude that dipstick results do not correlate well with the presence or absence of hematuria in patients with blunt trauma. Microscopic urinalysis is a better test on which to base the decision to perform further diagnostic tests in the evaluation of the urinary tract.