Investigating the incremental value of urine sediment reporting in emergency medicine with a Sysmex UN urinalysis system

Urinalysis is widely used and is also frequently requested in emergency situations for screening hypovolemia, urinary tract infections, diabetes, ketoacidosis and hematuria. Our aim was to evaluate the impact of reporting urinary sediment in emergency department specimens with the Sysmex UN system. We evaluated urinalyses requested by the emergency department over a three-month period and examined red blood cell count interference, compared leukocyte esterase dipsticks to cytofluorimetric leukocyte count and nitrites to cytofluorimetric bacterial count. We then examined digital microscopy images to identify additional elements of interest or pathology. We collected 532 cases, 354 with only chemical and cytofluorimetric analysis and 178 with digital microscopy. Automated erythrocyte counting showed a 7 % error rate, mainly false-positive results. Leukocyte esterase had a sensitivity of 88.22 % and specificity of 88.84 % at the lower limit, while nitrites had a sensitivity of 41.06 % and a specificity of 99.38 %. Pathological elements were detected in 126 samples by digital microscopy: 70 had casts, 36 crystals and seven cells with high pathological value. Evaluation of urine sediments by trained specialists can provide potentially important information even in emergency situations, whereby the pre-analytical phase must always be taken into account.