4. Physical Examination
1. Volume Proportional to water in take by a
person. Useful terms:
- Polyuria – consistent abnormal excretion of
large volume of urine (Diabetes)
- Oliguria – Opposite of polyuria (Diarrhoea)
- Anuria – Complete absence of urine formation
5. - Nocturia – Passing of >500ml of urine by adult
at night
- Diuresis – any increase in urine volume!
2. Specific gravity
A measure of amount of dissolved substances in
urine, a diagnostic tool.
3. Colour – Clear, Pale yellow depending on
concentration.
6. • Chemical Examination of Urine analysis
Used to detect glucose, protein, pH, blood,
ketone, esterase, bilirubin etc.
Various methods for the detection of abnormal
chemical substances are available.
Most of the methods are qualitative.
Traditional chemical tests:
7. Dry reagent strips:
Plastic strips impregnated with appropriate
reagents.
Strip is dipped in urine, a chemical reaction
denoted by change of colour takes place.
Automated method is available to read the tests.
8. Automated method is available to read the tests.
Results reported as:
- = Negative
+/- = Trace
+ = Light
++ = Moderate
+++ = Heavy
++++ = Very Heavy
9. Examination of Urine
Microscopy:
1.Wet preparation: a. Neat Urine
b. Centrifuged urine
Examination: At least in 4 hpf, count the number
of pus cells, rbc and casts in each field and take
the average. Report as e.g. 2-4/hpf.
Other findings are scored qualitatively i.e. +, ++,
+++ etc.
10. Interpretation:
Neat Urine: 1-2 pus cells per hpf is significant.
Urine to be cultured.
Centrifuged urine: Normal Urine may contain
<5pus cells/hpf. Urine may not be cultured; but if
>5/hpf, then culture.
11. Limitations: Neat urine: Not fully representative
as casts and ova may not be seen.
Centrifuged urine. Representative but more time
consuming.
2. WHO method: A known volume of 60ul of
well mixed urine is placed in pre-labeled 96 flat
well micro-titre tray. Allow to settle for at least 5
minutes.
Examine with x20 objective of an inverted
microscope.
12. Reporting:
WBC count recorded as:
<10/ml
10-100/ml
100-500/ml
>500/ml
Other findings may be recorded as:
-/+ = Scanty
+ = Few
++ = Moderate
+++ = Many
13. Limitations: In experienced hand, the method is
ideal though costly. There is no need for
centrifugation. Many samples are examined in one
preparation.
3. Gram Stain: Some workers do Gram stain on
samples containing pus cells and bacteria.
This is an additional test and may not necessarily
be advantageous.
Contamination is indicated by mixed flora of
bacteria.
14. 4. Darkground Microscopy: This is performed
when leptospirosis is suspected.
A wet prep. of centrifuged urine is made for DG
examination.
5. Ziehl-Neelsen Stain: This is done if renal
tuberculosis is suspected.
Make smear of the sediment from three
centrifuged early morning urine specimens.
15. Clinical significance of abnormal microscopic
findings:
1. Pus cells: Indicates inflammation of UT,
referred to as pyuria.
i. Infection-cystitis, urethritis etc.
ii. Acute or chronic bacterial pyelonephritis
iii. Calculi
16. 2. Red blood cells: Indicates haematuria,
indicative of:
i. Renal diseases – glomerulonephritis
ii. S. haematobium infection
iii. Physiological changes.
3. Yeast cells: can be differentiated from red
cells by their oval shape and some of the yeasts
usually show single budding.
Indicates faecal contamination, vaginal candidasis
or diabetes due to high content of glycogen.
17. 4. Epithelial cells:
Nucleated and vary in size and shape
Usually few in normal urine but large numbers,
however, usually indicate inflammation of the
UT or vaginal contamination of the specimen.
5. Casts
Consist of solidified protein and are cylindrical in
shape, because they are formed in the kidney
tubules.
There are several types of casts:
18. Hylanine casts
Colourless and empty
Associated with damage of the glomerular filter
membrane
Waxy casts:
Hyaline casts that have remained in the kidney
tubules for a long time, they are thicker and denser
than hyaline casts, often indented or twisted.
Indicate tubular damage or renal failure.
19. Cellular casts:
Contain white blood cells or red blood cells:
- Rbcs casts indicate haemorrhage into the renal
tubules or glomerular bleeding
- Wbc casts found in inflammation of the kidney
pelvis or tubules.
Granular Casts:
Contain irregular size granules originating from
degenerate cells and protein.
Associated with renal damage.
20. 6. Crystals
Normal urine contains many chemicals from which
crystals can form, and therefore the finding of most
crystals are of little clinical importance.
Crystals which may be found in metabolic
disorders include:
Cystine Crystals
Six sides, soluble
Found in cystinuria
21. Tyrosine crystals
-Yellow or dark coloured, like needles massed
together,
- Insoluble in ethanol
- Occasionally found in severe liver diseases
Cholesterol crystals
- Rectangular with cut-out corners
- Insoluble in acid and alkalines
- Rarely found except in severe kidney disease
22. Other crystals found in Urine:
- Sulphonamide – Patient treated with
sulphonamides, can cause haematuria and
other complications.
- Triple phosphate crystals found in alkaline
urine. No clinical significance.
- Calcium oxalate and uric acid may indicate
calculi in the urinary tract.
23. 7. Parasite
These include
- Eggs of Schistosoma haematobium. The urine
contains Rbc’s and protein
- Trichomonas vaginalis
8. Bacteria:
- Indicates a urinary infection in the presence of
pus cells
- Usually rods, but sometimes cocci
24. 9. Spermatozoa
- Large number may be pathological.
In the absence of urine microscopy, urinanalysis
(reagent strips) can give enough indication for
bacteriological culture of urine.
e.g. Esterase # = increase in WBC count in urine.
Blood # = increase in RBC
Protein # = Bacterial infection
25. Urine Culture
A definite proof of infection in the urinary tract.
Pyuria is suggestive but not necessarily so.
Some laboratories do not culture urine that are
biochemicaly and microscopically normal.
Some laboratories culture all samples so as not to
misdiagnose asymptomatic bacteriuria.
26. Significant bacteruria:
- The magic number is 105 CFU/ml which
indicates infection.
- Several methods are available to determine
significant bacteriuria.
- These are semi-quantitative culture methods.
27. Pour plate method:
A known quantity of urine is diluted in cooled
molten nutrient agar, poured into petri dish,
allowed to set and incubated.
The colonies in and on the medium are counted.
Surface drop method (Miles Misra). Time
consuming and laborious. Not meant for routine
work.
28. Standard Loop Method: The most popular and
convenient method:
- Holding a sterile calibrated loop vertically, dip the
loop into a well mixed uncentrifuged urine and
inoculate the medium of choice. e.g. CLED.
|- Incubate plate overnight and count colonies.
- A single colony is accepted to represent one colony
forming unit (CFU).
29. Calculation of significant bacteruria:
Using 0.001ml loop:
If 1 loopful (0.001) produces 100 cfu.
Therefore, the number of bacteria/ml
= 100 ÷ 0.001
= 100 x 1000 = 100,000 (105)
Filter paper method: Now superseded by The
Standard loop method.
30. Dipslide method
- Unit of universal container into which slide
containing media on both sides, is enclosed.
- Minimises contamination otherwise no special
advantage over the standard loop method.
Additional cultures
1. If typhoid fever is indicated:
- Centrifuge 10ml urine in a sterile tube at high
speed for 10 minutes.
31. Re-suspend sediment and transfer to a container of
selenite F broth. Incubate overnight and
subculture to XLD or DCA.
2. If TB is indicated: Early morning urine for 3
consecutive days. Pool the samples and
centrifuge. Decontaminate and inoculate 200ul on
an LJ medium.
3. Direct antibiotic sensitivity may be done in the
presence of numerous pus cells and bacteria.
32. Interpretation of bacterial count (urine
quantitative culture)
In our SQUH diagnostic laboratory.
Standard 1/300ml loop is used.
Culture yielded 333 cfu i.e. 1/300ml of urine
produced 333 cfu.
300 x 333 = 105 CFU/ml
Since 100,000 CFU/ml is significant bacteriuria,
any count of 333 and above is significant
33. Less than 33 cfu = <104 organisms/ml
333 cfu = 105
More than 333 cfu = >105
Reporting: Using 1/300ml Standard loop.
1.If less than 33 cfu of any organisms and if the
patient is not on antibiotic, report as:
No significant growth.
34. 2. If 33-330 cfu with no pus cells seen:
a. When pure, report as 105 cfu/ml with
antibiotic sensitivity if the patient is on
antibiotic or pregnant.
b. When mixed, report as mixed growth of
doubtfulsignificance with no antibiotic
sensitivity.
3. >330 CFU and pure, report as >105 CFU/ml (or
significant growth) with antibiotic sensitivity.
35. 4. If mixed growth of 2 different organisms of
equal number of >330 CFU in the presence of pus
cells, report as >105 cfu/ml or significant growth
with antibiotic sensitivity on both organisms.
5. If mixed growth of more than 2 different
organisms in numbers >330 cfu and in the
presence of pus cells, report as mixed growth and
request for repeat sample.
36. 6. In SPA specimens, any isolate is treated as
significant and reported with sensitivity.
Merci
