How to Load Microhematocrit Tubes: TrueBond Duet Rotor Guide

Microhematocrit testing provides a direct way to measure packed cell volume (PCV) by centrifuging a blood sample in a capillary tube and reading the resulting packed red blood cell column. Consistent sample preparation, tube loading, centrifugation, and reading technique are all important when performing a spun PCV.

Drucker Diagnostics’ TrueBond Duet veterinary centrifuge comes with a 12-place microhematocrit rotor designed for 40 mm microhematocrit tubes. Properly preparing and loading the tubes helps ensure safe, reliable performance with every spin.

How to Prepare and Load Microhematocrit Tubes

Follow these steps when preparing 40 mm microhematocrit tubes for the TrueBond Duet.

1. Fill the Microhematocrit Tube

Hold the capillary tube at an angle with one end in the blood sample. Allow the blood to enter the tube by capillary action rather than forcing it in. Fill the tube approximately three-quarters full.

2. Wipe Away Excess Blood

After filling the tube, wipe any excess blood from the outside of the tube. This helps keep the outside of the tube free of excess sample before sealing and loading.

3. Seal the Tube

Press the dry end of the tube firmly into the sealing clay. Push it far enough into the clay to form a complete seal.

4. Inspect the Seal

Before loading the tube into the rotor, inspect the clay plug to make sure it has full contact with the tube.

5. Load the Rotor

Place each tube into the microhematocrit rotor with the clay-sealed end facing outward, away from the center of the rotor. The clay-sealed end should sit flush with the outer rim of the rotor. Load the tubes symmetrically to maintain balance.

6. Run the Microhematocrit Cycle

Once the tubes are loaded and balanced, spin them using the microhematocrit cycle.

7. Read the Packed Cell Volume

After the cycle is complete, remove the rotor from the rotor chamber and place the round Duet reader card on top. Align the bottom of the packed red blood cell column at 0 and the top of the plasma column at 100. Read the percentage at the top of the packed red blood cell column, excluding the buffy coat.

8. Optional: Use the Microhematocrit Reader Card

The capillary tubes can also be removed from the rotor and placed individually in the slider on the Microhematocrit Reader Card. For each tube, align the bottom of the packed red blood cell column at 0 and the top of the plasma column at 100. Read at the top of the packed red blood cells and exclude the buffy coat.

Consistency Matters When Measuring PCV

Because spun PCV is a physical measurement of the packed red blood cell column, technique matters throughout the process. Consistent mixing, capillary preparation, sealing, centrifugation, and reading can all contribute to repeatable results.

Following the same preparation and loading steps each time gives operators a consistent process from sample collection through reading.

Microhematocrit Made Easy with the TrueBond Duet

The TrueBond Duet includes a 12-place microhematocrit rotor for 40 mm microhematocrit tubes, along with a reader card for reading the packed cell volume after centrifugation. Whether you are preparing tubes for a routine PCV or reviewing the loading process for your team, following the proper tube preparation, sealing, loading, and reading steps can help ensure safe, reliable performance with every spin.

Learn more about the TrueBond Duet or contact Drucker Diagnostics at +1-866-265-1486 or [email protected].