Is the microscopic exam necessary if the only abnormal finding on the dipstick is trace blood?
Due to the sensitivity of the reagent strips, trace blood may be indicated in healthy individuals. A. It is appropriate to follow a trace blood dipstick result with a microscopic examination of the urine sediment when performing a urinalysis. Reagent strips have varying degrees of sensitivity for red blood cells and hemoglobin. However, they react positively, or trace, when normal levels of RBCs are exceeded. In a healthy person, a few RBCs, such as one or two per high-powered field, may be found in urine sediment. If these numbers are exceeded, the dipstick should react positively. (The reaction pad is sensitive to an increase in hemoglobin content, not the number of RBCs.) Although a trace blood dipstick result can occur for a variety of reasons, some of which have no pathology associated, such as menstrual contamination or interfering chemical agents, a microscopic examination of the sediment should be conducted to help identify the cause of the trace blood. Meryl H. Haber, MD Scott
