Dipstick evaluation of hematuria in abdominal trauma

Urine microscopic evaluation of hematuria has traditionally been used to determine the need for an intravenous pyelogram (IVP) in individuals with blunt abdominal trauma. An IVP is generally advocated in cases where greater than 5-10 red blood cells per high power field (RBC/HPF) are identified. Various laboratories have advocated the use of dipstick examination of these urine specimens as a replacement for microscopic examination. Urine specimens from 178 consecutive patients with blunt abdominal injury were evaluated by dipstick (Chemstrip 9, Cat. No. 417190, Boehringer Mannheim Diagnostics) and microscopic examination. Sensitivity of dipstick testing for microscopic hematuria was 100% as compared to microscopic examination (positive greater than or equal to 5RBC/HPF); specificity was 58.6%. Predictive value of a positive test (PVP) was 60.8%; predictive value of a negative test (PVN) was 100%. Evaluation of proteinuria performed as an additional means of assessing renal integrity was found to be less sensitive, but more specific than, dipstick evaluation of hematuria. Poor correlation was seen between the degree of positivity by dipstick testing and the actual degree of microscopic hematuria. It is concluded that specimens which are negative for hematuria by dipstick do not need further testing by microscopic examination. All specimens which contain blood by dipstick evaluation need to be examined microscopically to predict the need for IVP.