What It Is Microscopic urinalysis is often done as part of an overall urinalysis. After a urine sample is collected, it's put into a centrifuge — a special machine that separates the liquid in the urine from solid components that may be present, such as blood cells, mineral crystals, or microorganisms. Any solid materials are then viewed under a microscope.
Why It's Done The results of a microscopic urinalysis may point to a urinary tract infection (UTI), kidney problems, a metabolic disorder such as diabetes, or a urinary tract injury. If test results are abnormal, other tests may be needed before a definite diagnosis can be made.
Preparation of urine and urinary sediment
Aspect Freshly voided urine is usually clear. The terms to describe the appearance of urine are: clear, slightly cloudy, cloudy, flaky, and turbid. A turbid specimen should be clarified before microscopic examination.
Material Standardization of the examination of the urinary sediment is recommended. The plastic tubes used for centrifugation should allow macroscopic observation and should be strong enough not to break during centrifugation. 10 ml of urine are sufficient for chemical analysis and microscopic examination. 12 mL graduated tubes with a conical bottom (to concentrate the sediment) should be used. Smaller volumes are used for children. Procedure Before chemical analysis (test strips), the samples must be clear and well mixed and the volume carefully measured. Centrifuge 10 ml of urine for 5 minutes at 400 g. Decant the supernatant leaving only 0.5 mL at the bottom of the tube.
20 µL of the staining solution of Sternheimer-Malbin can be added and mixed with 0.5 mL of concentrated sediment. Drop 10 µL of the colored or uncolored suspension on a glass slide and cover with a cover slip. An exact concentration factor is crucial for a valid correlation to the urinary volume. The concentration factor between the initial volume and/or the supernatant is approximately 10 to 25. 20 µL
Next, proceed to the microscopic examination of the sediment