Urolithiasis is one of the most common urologic disease encountered in the emergency room and nearly all are associated with gross or microscopic hematuria, but sometimes without any evidence of blood in the urine. We retrospectively reviewed 149
patients who underwent intravenous urogram (IVU) among 226 patients who presented with flank pain to the Kang Nam General Hospital emergency department from January 1995 to June 1996. We then investigated the incidence and characteristics of
negative
hematuria (<3RBC/HPF) in patients with urinary tract stone diagnosed by IVU.
133 patients (89.3%) among the 149 patients were diagnosed as urinary stone, and the stone predictability based on hematuria positive and negative result of urinalysis was 89.8% (123/137) and 83.3% (10/12), respectively. Among the 133 urinary
stone
patients, 123 (92.5%) patients had positive urinalysis and 10 (7.5%) patients had negative urinalysis. The incidence of negative hematuria based on urinalysis alone was 7.5%. They were consisted of KUB positive in 10 cases (100%), upper and lower
tract
stone in 3 and 7 cases respectively, 5mm in average size of the stone, ad severe obstruction in 8 cases(80%). The incidence of negative hematuria based on the combination of urinalysis and urine dip-stick test (UDT) was 5.3%. No statistically
significant differences were observed in clinical factors of stone history, duration of pain, positve KUB, stone size and negative UDT result between negative and positive hematuria group. But we found a statistically significant difference in
clinical
factor of severe obstruction.
The overall incidence of negative hematuria in patients with urinary stone presenting to the emergency room was relatively low (7.5% in urinalysis only, 5.3% combined with UDT), but hematuria negative group showed more significant severe
obstruction
rates than positive hematuria group. Moreover, there was no significant difference in stone predictability between two groups. Therefore, in patients with flank pain and hematuria negative at emergency room, IVU should carefully be proceeded by
physician.
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