Formed_Elements_in_Urine_Strasinger7th.pdf

analysis of urine and other body fluids

1. Formed Elements in Urine (Excluding Crystals)
Reference: Strasinger, S.K. & Di Lorenzo, M.S., Urinalysis and Body Fluids, 7th Edition
Name of Sediment Characteristics Appearance in Microscopy Manner of Reporting Clinical Significance
Red Blood Cells (RBCs) Small, non-nucleated biconcave discs; may appear crenated in concentrated urine or as ghost cells in dilute urine. Yellow to colorless, round, refractile discs; may appear swollen or crenated depending on urine concentration. Average number per high-power field (HPF). Indicates hematuria; associated with glomerular damage, infection, stones, trauma, or menstrual contamination.
White Blood Cells (WBCs) Spherical cells with granular cytoplasm and multilobed nucleus (mostly neutrophils). Slightly larger than RBCs; granular and refractile; may exhibit Brownian movement. Average number per HPF. Indicates pyuria; seen in UTI, inflammation, or renal infection.
Squamous Epithelial Cells Large, flat cells with abundant cytoplasm and small, central nucleus; originate from distal urethra or vagina. Thin, irregular sheets or single cells with distinct borders and central nuclei. Average number per HPF. Usually contaminants; not clinically significant unless numerous (poor specimen collection).
Transitional (Urothelial) Epithelial Cells Round, pear-shaped, or caudate; single central nucleus; originate from renal pelvis, ureter, bladder, or upper urethra. Medium-sized, granular cytoplasm, well-defined borders; may appear singly or in clusters. Average number per HPF. Increased in catheterization, infection, or transitional cell carcinoma.
Renal Tubular Epithelial (RTE) Cells Small, round cells with eccentric nucleus; derived from renal tubules. Slightly larger than WBCs; coarsely granular cytoplasm; may contain absorbed substances (lipids, pigments). Average number per HPF. Indicates tubular injury — acute tubular necrosis, toxic damage, or viral infection.
Hyaline Casts Composed mainly of Tamm-Horsfall protein; transparent and colorless. Smooth, cylindrical, colorless, low refractive index. Average number per low-power field (LPF). Normal in small numbers; increased in dehydration, exercise, fever, or mild renal disease.
RBC Casts Contain intact or fragmented RBCs embedded in a protein matrix. Cylindrical with red or brown RBCs visible within; may appear granular. Average number per LPF. Indicates glomerulonephritis or bleeding within the nephron.
WBC Casts Casts with numerous WBCs (mostly neutrophils). Cylindrical, granular, opaque structure with visible WBCs. Average number per LPF. Seen in pyelonephritis, interstitial nephritis, or inflammatory renal disease.
Granular Casts Result from cell degeneration or plasma protein aggregation. Cylindrical with coarse or fine granules; varying texture and density. Average number per LPF. Seen in renal disease, exercise, or stress.
Waxy Casts Final stage of cast degeneration; homogeneous with notched or cracked ends. Highly refractile, opaque, with blunt or broken ends. Average number per LPF. Indicates chronic renal failure or tubular atrophy.
Fatty Casts Contain fat droplets or oval fat bodies within the cast matrix. Refractile droplets within a cylindrical cast; show Maltese cross under polarized light. Average number per LPF. Indicates nephrotic syndrome and lipiduria.
Broad Casts Wider than typical casts; formed in dilated tubules. Wide, blunt-ended cylinders; may be granular or waxy in appearance. Average number per LPF. Indicates end-stage renal disease or severe tubular destruction.
Bacteria Small rods (bacilli) or cocci; may show motility. Tiny, refractile dots or short rods; often clustered; distinguish from amorphous debris. Report as few, moderate, or many per HPF. Indicates UTI when accompanied by WBCs; contamination possible.
Yeast Oval, refractile cells; may show budding or pseudohyphae formation. Round or oval budding cells; may form chains resembling hyphae. Report as few, moderate, or many per HPF. Indicates Candida infection; often seen in diabetics or contaminated female specimens.
Parasites Most commonly Trichomonas vaginalis; motile, flagellated protozoa. Rapid, darting, jerky motility; pear-shaped, slightly granular organisms about WBC size. Report as 'Trichomonas present' or 'Parasite present (specify)'. Indicates urogenital infection or contamination from vaginal secretions.
Mucus Long, thread-like glycoprotein strands secreted by glands and epithelia. Transparent, wavy threads; low refractility; may form tangled masses. Report as present, moderate, or abundant. Common in female urine; may increase with inflammation or irritation.
Spermatozoa Mature male reproductive cells; oval head with long, thin tail. Motile cells with distinct oval head and long flagellum. Report as present. Normal after ejaculation; may indicate retrograde ejaculation in males.
Artifacts Extraneous materials such as fibers, starch, oil droplets, air bubbles, pollen, or talc. Varies in shape and refractility; may mimic true cells or casts. Report as 'present (specify type if known)'. Not clinically significant; result of contamination during collection or processing.
Oval Fat Bodies Renal tubular epithelial (RTE) cells that have absorbed lipid droplets. Bright, refractile oval cells filled with multiple fat droplets; show Maltese cross under polarized light; droplets stain orange-red with Sudan III or Oil Red O. Report as few, moderate, or many per HPF. Indicates lipiduria, typically seen in nephrotic syndrome, diabetes mellitus, or acute tubular damage.