CM LEC 5: MICROSCOPIC EXAMINATION OF URINE

microscopic examination of urine

Done to detect and identify formed elements found in urine

microscopic examination of urine

This Includes RBC, WBC, epithelial cells, casts, bacteria, yeast, parasites, mucus, spermatozoa, crystals and artifacts.

thomas addis (1926)

● Developed the first procedure to standardize the quantitation of formed elements in urine

● “Addis Count”

○ He used a hemocytometer to count the number of red blood cells (RBCs), white blood cells (WBCs), casts, and epithelial cells present in a 12-hour specimen.

○ This was mainly used to monitor the course of diagnosed cases of renal diseases.

○ This has been replaced by various titer dyes commercial system.

addis count

What urine quantitative test is used to measure the number of red blood cells, white blood cells, epithelial cells, and casts excreted over a 12-hour period?

CONVENTIONAL METHOD (IN DOING THE EXAMINATION OF URINE SEDIMENT)

● Placing a drop of centrifuged urine on a glass slide, add a coverslip, and examined microscopically.

● This is the method used in the laboratory

Urine should be examined fresh or adequately preserved

SPECIMEN PREPARATION

dilute alkaline urine

(SPECIMEN PREPARATION) Formed elements (RBCs, WBCs, and hyaline casts) disintegrate rapidly.

refrigeration

(SPECIMEN PREPARATION) This causes precipitation of amorphous urates and phosphates and other nonpathologic crystals.

37-degrees Celsius

In order to remove these crystals, you have to warm the specimen to ___ prior to centrifugation to dissolve some of these crystals.

midstream clean-catch specimen

Minimizes external contamination of the sediment

MIX ; PRIOR TO

Thoroughly ___ urine ___ decanting a portion into a centrifuge tube.

6 ml

(SPECIMEN VOLUME) Can be used for pediatric patients

10 - 15 ml

(SPECIMEN VOLUME) Range used

12 ml

Frequently used volum

Multiparameter reagent strips

___ ___ __ easily immersed, capped centrifuge tubes often calibrated to the 12 mL volume

5 minutes

Centrifuge specimen for ___ at 400 RCF (Relative Centrifugal Force)

400 RCF

Centrifuge specimen for 5 minutes at ____

relative centrifugal force

RCF

RCF = 1.118 x 10 x radius (in centimeters) x −5 𝑟𝑝𝑚 2

Convert RPM to RCF using the following formula:

radius (in centimeters)

refers to the distance from the center of the rotor to the outermost point of the cup tube or trunnion when the rotor is in motion.

0.5 to 1 mL

(SPECIMEN PREPARATION AFTER CENTRIFUGATION) A uniform amount of urine and sediment should remain in the tube after decantation

20 microliters (ul)

(SPECIMEN PREPARATION AFTER CENTRIFUGATION) Volume of sediment:

resuspend

___ sediment by gentle agitation to provide equal distribution of elements in the microscopic examination field.

gentle agitation

Resuspend sediment by ____ to provide equal distribution of elements in the microscopic examination field.

equal distribution

Resuspend sediment by gentle agitation to provide __ ___ of elements in the microscopic examination field.

12:1 to 30:1

(SPECIMEN PREPARATION AFTER CENTRIFUGATION) The sediment concentration ranges from ___ to ___

12:1 concentration

(SPECIMEN PREPARATION AFTER CENTRIFUGATION) For manual techniques:

examination of sediment

(EXAMINATION OF SEDIMENT) After getting the sediment, you should proceed to the ___ ___ ____

10 low power field (LPF) and high power field (HPF)

(EXAMINATION OF SEDIMENT) A minimum of ___ and ___ are examined

unstained

(EXAMINATION OF SEDIMENT) The sediment is examined ___, therefore you should examine it under reduced light when using bright-field microscopy.

reduced light

(EXAMINATION OF SEDIMENT) The sediment is examined unstained, therefore you should examine it under ___ when using bright-field microscopy.

bright-field microscopy

(EXAMINATION OF SEDIMENT) The sediment is examined unstained, therefore you should examine it under reduced light when using ____.

Casts

(EXAMINATION OF SEDIMENT) ___ are usually found near the edges of the cover slip.

near the edges

(EXAMINATION OF SEDIMENT) Casts are usually found ___ __ ____ of the cover slip.

low power objective (LPO) ; 10 FIELDS

(EXAMINATION OF SEDIMENT) When you do examination of sediment, you first scan using the ____  and scan ____, then proceed to the high power objective (HPO) and scan 10 HIGH POWER FIELDS

high power objective (HPO) ; 10 HIGH POWER FIELDS

(EXAMINATION OF SEDIMENT) When you do examination of sediment, you first scan using the low power objective (LPO) and scan 10 FIELDS, then proceed to the ___ and scan _____

Average number per low power field (examination of 10 fields)

(REPORTING OF MICROSCOPIC EXAMINATION) CASTS

Average number per 10 high power fields

(REPORTING OF MICROSCOPIC EXAMINATION) RBCs AND WBCs

Semiquantitative terms (rate, few, moderate, and many or as 1+, 2+, 3+ and 4+) per LPF/HPF following (or depending on laboratory format)

(REPORTING OF MICROSCOPIC EXAMINATION) EPITHELIAL CELLS (EC), CRYSTALS, AND OTHER ELEMENTS

Rare

(QUALITATIVE TERMS AND DESCRIPTIONS FOR FIELDS OF VIEW (FOV) [Element or sediment constituent] Present, but hard to find

1+

(QUALITATIVE TERMS AND DESCRIPTIONS FOR FIELDS OF VIEW (FOV) [Element or sediment constituent] Present, but hard to find

Few

(QUALITATIVE TERMS AND DESCRIPTIONS FOR FIELDS OF VIEW (FOV) One (or more) present in almost every field of view

1+

(QUALITATIVE TERMS AND DESCRIPTIONS FOR FIELDS OF VIEW (FOV) One (or more) present in almost every field of view

Moderate

(QUALITATIVE TERMS AND DESCRIPTIONS FOR FIELDS OF VIEW (FOV) Easy to find; number present in FOV varies; “more than few, less than many”

2+

(QUALITATIVE TERMS AND DESCRIPTIONS FOR FIELDS OF VIEW (FOV) Easy to find; number present in FOV varies; “more than few, less than many”

Many

(QUALITATIVE TERMS AND DESCRIPTIONS FOR FIELDS OF VIEW (FOV) Prominent; large number present in all FOV

3+

(QUALITATIVE TERMS AND DESCRIPTIONS FOR FIELDS OF VIEW (FOV) Prominent; large number present in all FOV

Packed

(QUALITATIVE TERMS AND DESCRIPTIONS FOR FIELDS OF VIEW (FOV) FOV is crowded by or overwhelmed with the elements

4+

(QUALITATIVE TERMS AND DESCRIPTIONS FOR FIELDS OF VIEW (FOV) FOV is crowded by or overwhelmed with the elements

fields of view

FOV