Urine Microscopy - Urinary Sediment Examination Instructions
Preparation of the urine for microscopic examination:
• Clean catch or catheterized fresh urine, AM first or second void if possible
• If collected from a foley catheter, request fresh urine from tubing, not from bag
• Perform dipstick testing, note the PH, specific gravity and the presence of protein, blood or leukocyte esterase
• Fill conical bottom test tube with urine
• Fill another tube with an equal volume of water as a counterbalance
• Centrifuge at 1500-1800 rpm (or RCF of 400) for 5-7 minutes
• Pour off the supernatant leaving only 0.5 to 1 ml
• Resuspend the sediment by gently flicking the bottom of the tube
• Add one drop of SM stain if desired and allow 1 minute for stain uptake
• Alternatively, to better identify lipids, add 3-5 drops Of Sudan Ill stain and allow 5-10 minutes for uptake
• Note - you can add Sudan III stain to sediment that has already been stained with SM. It will displace any SM stain taken up by cells or casts and will stain lipid elements instead
• Use a pipette to transfer one drop of urine sediment to a glass slide and cover with a glass coverslip
• Do not use plastic or multi-well slides commonly used in central labs
Microscopy technique:
• Use a high quality microscope with xl 00, x400, and xl 000 magnification
• Ensure microscope objective, eyepiece, and condenser lenses are always clean
• Verify proper illumination of the specimen (Köhler Illumination) by adjusting the field diaphragm and condenser focus
• Use different illumination modalities if available
- Bright-field offers the best resolution but the least contrast (best when used with SM stain) -Add contrast by adjusting the iris diaphragm - note that this will decrease resolution in the process
- Darkfield is useful for rendering unstained or transparent elements against a dark background. Facilitates identification of lipids (especially with Sudan Ill stain) and crystals
- Phase_contrast enhances contrast, but at the expense of resolution. Very useful for identifying dysmorphic RBC's, lipids, crystals, and visualizing the protein matrix of casts
- Polarization is useful for identification of lipids, crystals, and contaminants
Dr. Jay R. Seltzer @jrseltzer
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