Microscopic Examination of Urine PDF

# Microscopic Examination of Urine ## Macroscopic Screening ### Specimen Preparation: - Fresh or preserved (adequate preservation) - Formed elements disintegrate rapidly in diluted alkaline urine. ### Specimen Volume: - 12 mL= microscopic volume ### Centrifugation: - To concentrate to get...

# Microscopic Examination of Urine ## Macroscopic Screening ### Specimen Preparation: - Fresh or preserved (adequate preservation) - Formed elements disintegrate rapidly in diluted alkaline urine. ### Specimen Volume: - 12 mL= microscopic volume ### Centrifugation: - To concentrate to get the sediment. - 400 RCF or 5 minutes ## Urine Sediment Stain Characteristics | Stain | Action | Function | |---|---|---| | Sternhelmer-Malbin | Delineate structure & contrasting colors of nuclei & cytoplasm | Identify WBC, epithelial cells & casts | | Toluidine Blue | Enhance nuclear detail | Differentiate WBC from RTE cells | | 2-3%- 12% Acetic Acid | Lyses RBC; enhance nuclei of WBCs | Distinguished RBCs from WBCs; yeast, oil droplets & crystals | | Lipid Stains: Oil Red O & Sudan III | Stain TAC; mural do not stain cholesterol | Identify free fat droplets & lipid-containing cells & casts | ## Sediment Stain: Supravital Stains - **Sternheimer-Malbin stain:** consists of: - Crystal violet - Sofcamn 0 - **Function:** absorbed well by WBC, epithelial cells & casts; providing delineation of contrasting color nucleus & cytoplasm. - **0.5% Toluidine Blue:** - Metachromatic stain - **Function:** - Enhancement of nuclear detail. - Differentiation between WBCs & RTE. - **2% Acetic Acid:** - Nuclear detail of WBC & epithelial cells. - RBC lysed by acetic acid. - **Lipid Stain:** - Oil Red O & Sudan III= most common; neutral fat. - Polarizing microscopy- chole= Maltese cross. ## Sediment Stain: - **Hansel Stain:** - **Composition:** - Methylene blue - Eosin Y - **Function:** Identifies urinary eosinophils. - **Gram Stain:** - **Function:** - Differentiation between gram-positive (blue) & gram-negative (red). - Identification of bacterial casts. - **Prussian blue stain:** - **Function:** Identifies granules of iron in cells and casts. ## White Blood Cells (WBC)/ Pus Cells - **Neutrophils:** - Predominant WBC. - Granulated, multi-lobulated. - **Function:** - In alkaline solutions, neutrophils exhibit glistening of granules. - **Eosinophils:** - Significant if present at >1%. - Indicative of acute interstitial nephritis. - **Stain:** Hansel Stain. - **Lymphocytes:** - Single, round to slightly oval nucleus and scant clear cytoplasm. - Predominate in urine from patients experiencing renal transplant rejection. - Chem Reagent Strip: LE. - **Monocytes, Macrophages, Histiocytes**: - Actively phagocytic cells. - Histiocytes- monocytes that reside in the interstitial tissues. ## Other Cells: - **Squamous Epithelial Cells (SEC):** - Most common & largest epithelial cells; found in the urine. - Represent normal sloughing and have no pathologic significance. - **Site:** - Female: Entire urethra. - Male: Distal portion of the urethra. - **Transitional/Urothelial Epithelial Cells (TEC):** - Found in small numbers in normal urine. - Represent normal cellular sloughing. - **Renal Tubular Epithelial Cells (RTE):** - Most clinically significant cells. - Epithelium that lines each portion of nephron or renal tubule. - Increase in RTE may indicate necrosis of the renal tubule, affecting overall renal function. - **Oval Fat Bodies (OFB):** - Lipid-containing RTE cells. - Seen in conjunction with free-floating fat droplets. - Confirmed by staining with Sudan III or Oil Red O & examined using polarized microscope. - **Bubble Cells:** - RTE containing non-lipid filled vacuoles. - Represent injured cell in which ER has dilated before cell death. - Indicative of acute tubular necrosis (ATN). ## Microscopic Quantifications: | Reporting | Mucus Thread (LPF) | Normal Crystals (HPF) | Epithelial Cells (LPF) | Bacteria (HPF) | |---|---|---|---|---| | Rare | 0-1 | 0-2 | 0-5 | 0-10 | | Few | 1-3 | 2-5 | 5-20 | 10-50 | | Moderate | 3-10 | 5-20 | 20-100 | 50-200 | | Many | >10 | >20 | >100 | >200 | | | | | | | ### **Average:** - **HPF:** - RBC - Oval Fat Bodies - WBC - RTE - **LPF:** - Edges of cast - Cast - Abnormal crystals ## Urinary Sediment Constituent: **Blood Cells** - **Red Blood Cells (RBC):** - **Appearance:** smooth, non-nucleated biconcave disks - **Tonicity:** - **Hypertonic:** crenated RBC; echinocyte - **Hypotonic:** swell, ghost cell - **Dysmorphic RBC (Acanthocytes):** hallmark finding of acute glomerulonephritis - **Difficult to recognize:** 2% Acetic acid (no hgb but intact membrane). - **Clinical Significance:** - Damage to glomerular membrane. - Vascular injury within the genitourinary tract. - Contamination with menstrual blood. - **Reporting:** - Average/10 HPF - **Correlation:** - Color= red - Reagent Strip Blood Reaction ## Microscopic Examination: - **Centrifugation:** 400 RCF for 5 minutes. - **Should be performed in a consistent manner & include observation of a minimum of 10 fields for both 10x (LPO) & 40x (HPO).** - Examined under reduced light using bright-field microscopy. ## Normal Values: - **RBC:** 0-2 or 0-3 HPF - **WBC:** 0-5 or 0-8 HPF - **Hyaline Cast:** 0-2 LPF