side sedimentation rate measures the distance red blood cells will fall along the length of a vertical tube over a given time period. Although it is a non-specific phenomenon, it is clinically used in certain chronic disorders, for example rheumatoid arthritis or tuberculosis as an index of progress of the disease. ESR is a rate of fall of RBCs in diluted plasma and is influenced by a number of interreacting factors. Basically, it depends upon the difference in specific gravity between red cells and plasma, but the actual rate of fall is influenced very greatly by the extent to which the red cells form roulette, which sediment more rapidly than single cells. Other factors which affect sedimentation include the ratio of red cells to plasma, the plasma viscosity, the bore of the tube, equipment and reagents, vestigrend rack, vestigrend tubes with internal diameter of 2.5 mm. These can be disposable or made of glass. A glass tube is graded from 0 to 190, whereas a plastic tube which has a white collar at the lower end is graded from 0 to 170. These gradings may vary with the make of the tubes. These little tubes are preferred, timer. ESR vacuotainers with black tops which contain 3.8% sodium citrate. Alternatively, tubes of minimum volume 2 milliliters can be used. In this case, one volume of 3.8% trisodium citrate solution is mixed with four volumes of blood. Preparation of 3.8% trisodium citrate solution mix 3.8 grams of anhydrous trisodium citrate with distilled water making the total volume up to 100 milliliters. Keep the solution in the refrigerator. If the solution is cloudy or contains particulate matter, discard and prepare a fresh solution. Specimens. Collect the sample within 6 hours of performing the test. Procedure. Standard precautions should be followed. Collect 1.6 milliliters of blood by any puncture in 3.8% sodium citrate vacuotainer and mix the contents thoroughly by inverting the vial at least 6 times. Alternatively, measure exactly 0.4 milliliters of the 3.8% trisodium citrate solution with the help of a pipette or syringe into a clean and dry tube. Draw Venus blood and immediately place 1.6 milliliters into the trisodium citrate solution. Note. You can also use ETA blood. If kept at 4 degree centigrade, it can be used up to 24 hours. In this case, mix the ETA blood well and place 1.6 milliliters into the trisodium citrate solution. Open the vacuotainer gently. The sedimentation pipette is inserted into the tube right to the bottom of it. The mixture is thus forced upwards and due to the zeroing system, the column falls exactly to the 0 milliliters position. Place the tube with the pipette into the stand provided, maintaining the serial number of the samples. Set the timer for 1R. Exactly after 1R, note the level to which the red cell column has fallen. Note the result in terms of millimetres at the end of R. After a series has been read, tubes and pipettes are disposed of intact as per waste disposal guidelines. Results and interpretation. The reference ranges of ESR for males and females are as follows. In childhood anodolycence, the ESR is the same as for men below 50 years with no difference between boys and girls. Remember the following to avoid errors while performing the test. Specimen used for testing should not be more than 6 hours old after collection. Blood and EDTA tubes can be used for up to 24 hours after collection, provided that it is kept at 4 degree centigrade. Use correct type and proportion of anticoagulant. Solution correct type of anticoagulant such as calcium oxalate can cause shrinkage of RBCs and decrease sedimentation. Only perform test on non-hemalized samples. Use sterile sedimentation tubes. Keep the tubes upright during sedimentation and check for air bubbles. Repeat test if air bubbles are present. Take care that the test is not performed near a heat source or direct sunlight. Do not perform the test adjacent to centrifuge or any instrument that causes vibration. Failure to read the test at exactly 1R will lead to erroneous results. Always check the highest graduation on the tube. This will give you the linearity of the test. If interlap comparisons are used as a method for proficiency testing, confirm that the other lab also performs tests with tubes of the same graduations.