Packed Cell Volume (PCV) measurement using a ruler provides a rapid estimation of the proportion of red blood cells in a blood sample. After centrifuging a blood sample in a hematocrit tube, the height of the red blood cell column is measured, along with the total height of the blood column (including plasma and buffy coat). A ruler is then used to determine these measurements in millimeters. The PCV is calculated by dividing the height of the red blood cell column by the total height of the blood column, then multiplying by 100 to express the result as a percentage.
The determination of PCV is a fundamental diagnostic procedure in veterinary and human medicine. It offers a quick and inexpensive assessment of a patient’s hematological status, particularly in the detection of anemia or dehydration. Historically, this manual technique served as the primary means of assessing red blood cell volume before the advent of automated hematology analyzers, and it remains valuable in resource-limited settings or as a confirmatory test.
