Hematuria after blunt trauma: when is pyelography useful?

Blood in the urine is common following blunt abdominal trauma. Most trauma centers routinely perform limited intravenous pyelography (IVP), usually with cystography, in such individuals presenting with any degree of hematuria in order to identify urinary tract injury. The observation that the yield of positive IVPs is small among such individuals, and the suspicion that a positive IVP rarely leads to a substantive change in outcome, resulted in the following retrospective study. We reviewed our Trauma Center's records for all patients undergoing IVP following blunt trauma in a 1-year period. Virtually all individuals had a cystogram performed. Positive studies were defined by various kidney, ureteral, bladder, or urethral abnormalities; bladder deviation by extrinsic pelvic hematoma was not counted as a positive finding. Among 156 patients undergoing IVP for hematuria in this period, 13 (8.3%) had an abnormal IVP or cystogram. Of these 13 patients ten (77%) had either gross or 4+ hematuria. Five patients (3%) required further diagnostic or therapeutic intervention. One patient (0.6%) required nephrectomy when exploration revealed renal artery thrombosis causing irreversible kidney ischemia. All five patients who required further evaluation or therapy presented with gross or 4+ hematuria. Had screening IVP been performed only in blunt trauma victims presenting with gross or 4+ hematuria, no patients with significant urinary tract injury would have been missed, and 119 (75%) of the patients in this series would have been spared the expenditure of time and money, and the radiation and dye exposure, resulting from their negative studies. Individuals in whom the possibility of renal injury is high following blunt trauma (flank pain or hematoma, low rib fractures) should undergo rapid limited IVP for diagnosis of significant genitourinary tract injury. Such evaluation should also be carried out in asymptomatic individuals who present with gross or 4+ hematuria. Microscopic hematuria alone, however, is a poor predictor of significant genitourinary tract damage. Our review suggests that asymptomatic victims of blunt trauma who have only small amounts of blood in the urine may safely be observed without routine emergency IVP.