Microscopic Examination of Urine Sediment

Abstract

To the Editor.— I read the letter from Robert M. Donauer, MD (240:2044, 1978), with much interest. There are two questions I would like to ask the author: Were the urine samples centrifuged before the dipstick tests? What kinds of findings were there among those 12% showing negative chemical screening tests and positive microscopic findings? My own study of roughly 1,000 random urine samples from an active community hospital showed that there is an approximate 6.5% chance that the dipstick will miss the socalled significant microscopic finding. The positive microscopic findings were defined as urine sediment with more than five WBCs per high-power field or more than three RBCs per high-power field or any casts. If I apply the author's criteria to the sample population from this institution, the false-negative rate becomes 3.6%. Dr Donauer may have obtained higher percentages of negative results by dipstick if he used