CLINICAL LAB SCIENEC

CHAPTER 12: PROCEDURES FOR URINALYSIS AND BODY FLUIDS 301
URINALYSIS AND BODY FLUIDS
ANALYSIS PROCEDURE #2
Microscopic Examination of Urine
Principles
Microscopic examination of urine sediment is a noninvasive
procedure that provides information useful in the diagnosis
and prognosis of certain diseases. For example, in renal
parenchymal disease, the urine usually contains increased
numbers of cells and casts discharged from an organ that
might otherwise be accessible only by an invasive procedure.
An aliquot (portion) of a urine sample is centrifuged, and
the sediment is examined using a brightfield microscope to
detect cells and other formed elements such as crystals and
casts.
Charts may be used to assist in identifying and defining
the sediment elements various crystals, and unidentifiable
artifacts obtained after centrifuging the sample.
Optimally, microscopic examination of a specimen require
a sample of more than 10 to 12 mL of fresh urine. In some
conditions, the patient is unable to void more than a very
small amount of specimen. Although the microscopic examination
may be performed with less than 10 mL of urine, the
minimum volume is 1 mL. Very small samples should be evaluated
without centrifugation and by slide and cover glass.
Perform the procedure as soon as possible after collection.
Procedural Alert
Interfering Substances That May Cause
Misleading Results.
It is essential that the laboratory worker
become aware of and account for the following:
1. Hyaline casts and other partially
transparent elements may be
obscured by excessively bright light.
Always use subdued light.
2. Vaginal secretions may contaminate the
urine with epithelial cells, bacteria, or
Trichomonas (a sexually transmitted
protozoan).
3. Urine may be contaminated with
fecal materials or Giardia
lamblia (a parasite).
4. Starch granules, oil droplets from lubricants,
antispermatic preparations,
fiber fragments, or bacteria and yeast
from contaminated urine containers may be
present.
Equipment and Supplies
1. Gloves, disposable paper towels, and disinfectant or other cleaning solution
2. Report form for urinalysis results (Procedure Report Form)
3. Fresh urine sample, preferably clean catch or catheterized, of at least 10 mL.
(minimum of 1 mL required)
4. Centrifuge and centrifuge tubes
5. Microscope slides with cover slips or an engineered system for performing
microscopic analysis (e.g., Kova)
6. Test tubes, test tube rack, and disposable transfer pipettes (may be part of some
standardized systems for urine microscopic examinations)
7. Brightfield microscope
8. 2% acetic acid and dropper
9. Normal saline solution and dropper
10. Biological stain for enabling easier identification of cells (optional)
Procedure
1. Wash hands and don gloves.
2. Assemble necessary equipment and supplies.
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