DETERMINATION OF SEDIMENTATION RATE (WINTROBE-LANDSBERG)
a. Principle. Anticoagulated blood is placed in a narrow tube. The blood cells
settle out of the suspension, leaving clear plasma above them.
The distance that the erythrocytes fall within a given interval of time is measured.
(1) Draw 5 ml of blood by venipuncture and place in a test tube containing
ethylenediaminetetraacetic acid (EDTA) (lavender top vacuum tube).
(2) Thoroughly mix the blood and anticoagulant by gently inverting the tube
several times, being careful not to cause bubbles.
(3) Draw the blood into the capillary pipet and fill the Wintrobe tube to the
"0" mark. This is done by inserting a capillary pipet to the bottom of the Wintrobe tube,
while holding it at an angle of 45. As the tube is filled, slowly withdraw the pipet so that
the tip is always just below the level of the blood. The blood count must be free of
(4) Place the filled Wintrobe tube in a rack in an exactly vertical position and
note the time and roan temperature.
(5) At the end of exactly 1 hour, read the level to which the red cells have
settled on the descending scale etched on the tube. Each mark equals 1.0 mm while
each numbered mark equals 10 mm (1 cm). The figure obtained is reported in mm per
hour as the "uncorrected" erythrocyte sedimentation rate.
(6) If a "corrected" sedimentation is requested, perform a hematocrit.
Calculators to correct for sedimentation rate are available in the Federal Supply
c. Sources of Error.
(1) The blood specimen must be properly mixed with the proper
anticoagulant to obtain an undiluted representative sample.
(2) The test should be set up within two hours after the blood sample is
collected to avoid a false low sedimentation rate.
(3) Increase in temperature accelerates the rate. Desirable temperature
range is 22C to 27 C.
(4) The tube must be vertical. A 3 variation from the vertical rate
accelerates the rate by 30 percent.