Which interpretation best explains the finding of a prominent fiber artifact in urine sediment analysis?

• A. It indicates glomerulonephritis
• B. It confirms the presence of a true cellular element
• C. It is most likely a lab artifact
• D. It indicates nephrotic syndrome

Answer: (C)

When you see a prominent fiber in urine sediment, the most reasonable interpretation is that it’s a lab artifact rather than a true urinary element. Fibers commonly enter the specimen during collection or processing—from cotton or textile fibers in the container, gauze, filter paper, or other lab materials. They appear as long, slender, refractile strands and typically lack cellular features such as nuclei, which helps distinguish them from real cells. This kind of contamination does not reflect glomerular disease or nephrotic-range pathology; those conditions produce distinctive findings like red blood cell casts, significant proteinuria, lipiduria, or other cellular components. The practical step is to treat it as contamination and, if needed, re-collect a clean specimen and re-examine to confirm the absence of true urinary elements.