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Ch 2: Urine Specimen Types, Collection, and Preservation

Urine Specimen Types and Collection

  • Purpose of Urinalysis

    • Aid in disease diagnosis

    • Screen for asymptomatic or hereditary diseases

    • Monitor disease progression and therapy effectiveness

  • Types of Urine Specimens

    • First Morning: Most concentrated, preferred for cytology

    • Random: Common for routine screening, no special timing

    • Timed: Predetermined collection for quantitative analysis (e.g., 24-hour collections)

Collection Techniques

  • Routine Void: No special preparation, patient voids into a container.

  • Midstream Clean Catch: Requires cleaning to avoid contamination.

    • Start urination into toilet, then collect midstream.

  • Catheterized: Involves sterile catheter insertion by trained personnel.

    • Urine flows directly into a bag.

  • Suprapubic Aspiration: Invasive, requires puncturing the bladder through the abdomen.

  • Pediatric Collection: Uses adhesive bags attached to skin to collect urine.

Specimen Volume Requirements

  • Routine analysis needs 10-15 mL; larger volumes (30-50 mL) preferred for split testing.

Specimen Rejection Reasons

  • Unlabeled or mislabeled containers

  • Inappropriate collection technique

  • Insufficient volume

  • Visible contamination

Changes in Unpreserved Urine

  • Altered solutes, bacterial growth, crystal precipitation

  • Observable changes: Decreased clarity, increased odor, color changes.

Urine Preservation Techniques

  • Refrigeration: Common method for preservation, but not for immediate testing.

  • Specific preservatives needed for cultures (e.g., boric acid).

Identifying Urine vs. Other Fluids

  • Urine higher in creatinine, urea, sodium, and chloride than other fluids.

  • Specific gravity range for urine: 1.002 - 1.035; pH range: 4.0 - 8.0.

  • Temperature checks for verification: below 32.5 °C or above 37.5 °C may indicate a non-urine sample.