Microscopy of Urine and Observations
Essentially, hematuria refers to the presence of blood in the urine. Clinically, a patient is found positive once it is confirmed that there are 5 or more red blood cells in a high-power field (under compound microscope) in three consecutive specimens.
Here, a patient may be asked to provide several samples that are centrifuged and viewed under the microscope. In the event that these samples are found to have 5 or more red cells under high-power field of view, then one is said to have hematuria.
There are two types of hematuria, which include:
- Gross hematuria - may
appear smoky, tea-colored or bloody. As such, the patient can detect that there
is blood in their urine
- Microscopic hematuria - In this case, the patient may not be able to tell that there is blood
in the urine, which means that it's asymptomatic. This requires the use of a
Some of the signs associated may
- passage of clots in urine
- dysuria and abdominal pain
- joint pains
Microscopy of Urine
Although gross hematuria can be detected without
using a microscope, one can still be used to determine the severity of
the condition. It's also important given that it helps confirm the presence of
red blood cells in urine.
However this is not always the case,
microscopic examination of urine may be performed as part of urinalysis.
Generally, urinalysis is used to detect and reveal such diseases as diabetes
mellitus and urinary tract infections among others. Urinalysis may include
various chemical, visual and microscopic tests.
Hematuria microscopy is specifically
aimed at detecting the presence (or the absence) of red blood cells in urine.
However, hematuria microscopy is part of the urinalysis tests.
- Urine sample
- Compound microscope
- Glass slide and cover
A clean, plastic container is used to collect urine for microscopy.
Here, it is often encouraged that the patient collect mid-state sample, which helps reduce chances of contamination while at the same time increasing accuracy. Basically, this means that the patient/individual should collect the urine halfway "mid-stream" rather than when they first start urinating.
While it can be stored for a period of up to 72 hours, it is often recommended that the sample be observed as soon as possible for specimen stability.
Shake the sample well and pour about 12ml of the
urine into a test-tube. Insert the test-tube into a centrifuge and set the
speed to between 2,000 and 3,000 rpm (rounds per minute). These are relatively
low speeds. The test-tube should be left in the centrifuge for about 8 minutes until
the sediment forms at the bottom. Once it is removed from the centrifuge, the
sample will have separated into a supernate and the sediment.
should be decanted leaving only a very small amount of about 0.5 ml to avoid
pouring out the sediment. To mix the sediment with the remaining supernate,
simply flick the bottom part of the tube and pour this on to the glass-slide.
Supernate - The supernate is the
liquid that remains at the top above the solid that settles at the bottom. This
separates from the denser solid at the bottom.
- Sediment - Sediments includes the
matter that settles at the bottom of the test-tube. When put in a centrifuge,
the rotation causes this matter which has higher density to travel to the
bottom of the tube and settle thus being separated from the less dense liquid.
Shaking the sample before adding some into the
test-tube is particularly important given that it allows for the contents of
the sample to spread. When the sample is allowed to settle, denser components
of the sample will gradually settle at the bottom, which would result in
inaccurate results. Therefore it's important that the sample be shaken to ensure
even distribution of urine components.
Relatively low speeds are
also recommended when the sample is being centrifuged. Although high speed
would mean quick results, it would also result in high pressure that may cause
hemolysis (bursting of the red cells). This would also affect the accuracy of
results when the sample is viewed under the microscope.
Related: Laboratory Centrifuge
Viewing Under the Microscope - Hematuria
Flicking the bottom of the test-tube helps mix
the remaining contents of the test-tube and make it possible to collect the
sediment. Once a drop of the sediment is placed on a clean glass slide, it should
be covered with a cover slip
Place the slide under the microscope (compound
microscope) and start with low power. Here, students will be able to view the
larger components of the sample including casts and crystals.
magnification, the student should be able to see (if present) the red blood
cells along with any other types of cells (bacteria etc) that may be present.
* Ideally, a urine sample should not contain any
red blood cells. However, due to various reasons (menstruation etc) it's
possible for some of these cells to find their way into urine. This becomes a
problem when 5 or more of the red cells are found in every field of view when
being observed under high magnification.
When viewed under the microscope, red blood
cells (in the sample) may appear to vary in shape and size.
For instance, they
may appear as:
- Normally shaped
- Partly hemolyzed
The red blood cells are likely to be swollen,
which is due to dilute urine. When the urine sample is very dilute, water moves
into the cell through osmosis. As water from the dilute urine enters the cell,
it swells and thus appears larger under the microscope.
In a hypertonic
state, the red cells will become crenated, which means that they lose water and
shrink. The cells will therefore be seen as notched objects under the
See also: Articles on Blood Microscopy and Blood Smear
Return to Red Blood Cells
Return to Urinalysis
Return from Hematuria to MicroscopeMaster Research Home
Roberts, James R. (2015) Urinalysis: Microscopy.