Packed Cell Volume

.Packed Cell Volume (PCV)

PCV: volume or the amount of the red blood cells in 100mL (dL) of blood.

Methods

A-Microhaematocrit.. B- Macrohaematocrit orWintrobe method. C-Electronic Cell Counting eg. Coulter Counter.

A.Microhaematocrit Method

Materials And instruments
1-Microhaematocrit tube contain heparin and show a red ring at the end of the tube.().


2-Microhaematocrit centrifuge :capable of producing an relative centrifugal force of 10000 to 15000g.()

4-Microhaematocrit reader()

Procedure
1-Blood is drawn into the tubes by capillary action . By holding the tubes in an horizontal manner and allow to filled with blood. Air bubbles denote poor technique but do not affect the results of the test. 2-Seal the dry end of the tube by heating dry end of the tube rapidly on a fine flame of Bunsen burner combined with rotation. 3-The sealed tube is then placed in the radial grooves of the Microhaematocrit centrifuge with the sealed end away from the center of the centrifuge and centrifuge for 5 minutes

4-When looking at a centrifuged haematocrit tube, you can see three distinct layers .A top layer of clear slightly milky plasma, a Buffy coat layer (consisting of WBC and platelets), and a dark packed RBC. (Fig.5). 5-Obtain the results using the microhaematocrit tube reading device.

B.Macrohaematocrit (Wintrobe) Method

Normal values for PCV: Normal range in adult men PCV is: 44-51%. If PCV is less than 44% in male condition is called anemia. If more than 51% in male condition is called polycythemia . Normal range in adult women PCV is: 38-48%. If PCV is less than 38% in female condition is called anemia.and if more than 48% in female condition is called polycythemia

:BLOOD INDICES

Introduction and PrincipleThe red blood cell indices are used to define the size and Hb content of the single red blood cell. Types:1.mean corpuscular volume(MCV)2.mean corpuscular hemoglobin(MCH) 3.mean corpuscular hemoglobin concentration(MCHC%).Objectives Are used as an aid in differentiating anemia’s.

Information Required 1-RBC count in millions / c.mm. 2-Hb estimation in g / dL. 3-PCV estimation as %.

Calculations

1-Mean Corpuscular Volume (MCV):The MCV indicates the average volume of single RBC.Its expressed in femtoliters(fL). PCV % MCV = ----------------------- RCB X6 /1 C.mm PCV = -------- --- X 1 0 = fL RCB normal range 80-100fL. So the RBC’s are normocytic .value less than 80 fl RBC’s are microcytic e.g. iron deficiency anemiavalue more than 1o0 fl RBC’s are macrocytic e.g. pernicious anemia

2-Mean Corpuscular hemoglobin (MCH):

3.Mean Corpuscular Hemoglobin Concentration (MCHC):
MCHC: is the average concentration of Hb in the single red blood cell. Its expressed as %. Hb(g/dl) MCHC = ------ ---------- PCV % Hb = ------------- x 100 PCV = %Normal value is 31-36% so the RBC’s are normochromic.If MCHC is less than 31% so the RBC s are hypochromic