Incidence of negative hematuria in patients with acute urinary lithiasis presenting to the emergency room with flank pain.

OBJECTIVES: To determine the incidence of negative hematuria in patients with acute urinary lithiasis presenting to the emergency room with flank pain.
METHODS: We retrospectively reviewed all 140 patients who presented with flank pain to the Long Island Jewish Medical Center emergency department from January 1, 1992, through December 31, 1992, and underwent intravenous urogram (IVU). We then calculated the incidence of negative hematuria in patients with acute urinary lithiasis (AUL) diagnosed by IVU based on the complete urinalysis alone or in combination with the urine dipstick test for blood.
RESULTS: We found a 14.5% incidence of negative hematuria in patients with AUL when looking at the urinalysis alone. To our knowledge, this has never been reported in the literature. We also found that by considering a negative combination (urinalysis plus urine dipstick test) as a new definition of negative hematuria, the incidence of negative hematuria in patients with AUL was only 5.5% (P < 0.031).
CONCLUSIONS: This is the first report in the literature documenting the incidence of negative hematuria in patients with AUL to be 14.5%. With the addition of the combination of urinalysis and urine dipstick test for hematuria, the incidence is only 5.5% and, therefore, represents a low yield when evaluated by IVU.