Microscopic Examination of Urine - Human Biology MSc Lecture 3

Centrifugation and Urine Analysis

• Centrifuging a urine sample at a relatively low speed helps to preserve formed elements like casts and cells.

Urine Sediment Analysis

• Abnormal numbers of red blood cells in urine indicate bleeding or inflammation in the urinary tract.
• Urinary casts are formed in the kidney tubules.

Cells in Urine

• The presence of pus cells (WBC) in urine suggests urinary tract infection (UTI).
• WBC casts are commonly seen in pyelonephritis, an infection of the kidney.

Preparing Urine Samples

• A drop of resuspended sediment is covered with a coverslip on a glass slide.

Urine Casts

• Hyaline casts are primarily composed of Tamm-Horsfall protein.
• RBC casts are formed in cases of glomerulonephritis.
• Granular and waxy casts are associated with chronic kidney disease (CKD).

Mucus and Sperm in Urine

• Mucus in urine is most commonly due to contamination from the genital tract.
• Sperm or spermatozoa in urine are often due to retrograde ejaculation.

Bacteria and Parasites in Urine

• Bacteria are common in urine specimens due to contamination during collection.
• The parasitic infection, Trichomonas, is sometimes detected in urine specimens.
• Yeast cells are often difficult to distinguish from red blood cells and amorphous crystals in urine specimens.

Crystals in Urine

• Common crystals seen in healthy patients include oxalate, phosphate, and uric acid crystals.