Lesson 27 — Hematology

Half B · HLT420B·Kinn's Ch 34·POC Testing & Lab (6%)

Source

All procedural steps, PURPOSE rationales, and topic content below are verbatim from MedCerts HLT420B Storyline modules. Quiz items have been normalized to multiple-choice format with verbatim source rationales. Reference textbook: Niedzwiecki & Pepper, Kinn's The Clinical Medical Assistant, 15th ed., Chapter 34. No outside material added.

Learning Objectives — NHA-aligned
Module L27-01 · Procedural skill

CLIA-waived Microhematocrit

Goal: To perform a microhematocrit test accurately.

Equipment
  • Provider's order and/or lab requisition
  • Microhematocrit lab log
  • Patient's health record
  • Fresh sample of blood collected in a tube containing ethylenediaminetetraacetic acid (EDTA) anticoagulant
  • Equipment for finger stick specimen: lancet, alcohol pad, gauze, bandage
  • Plastic-coated self-sealing capillary tubes, or plain capillary tubes (blue-tipped)
  • Sealing clay (if capillary tubes are not self-sealing)
  • Hematocrit centrifuge
  • Fluid-impermeable lab coat
  • Disposable gloves
  • Biohazard waste and sharps containers
  1. Sanitize your hands. Put on disposable gloves, fluid-impermeable lab coat, and protective eyewear.
    Purpose

    To ensure infection control.

  2. Assemble the materials needed.
  3. Fill two plain (blue-tipped) capillary tubes two thirds to three fourths full with the well-mixed EDTA blood by tipping the blood tube slightly and touching the capillary tube into the blood using the tip that is opposite the blue band.
  4. When enough blood is in the capillary tube, tip the blue end of the tube down causing the blood to flow towards the blue tip.
  5. Then readjust the tube horizontally while inserting the blue tip of the capillary tube into the clay sealant.
  6. Insert the tube as many times as needed to achieve a plug up to the blue band.
  7. If the capillary tubes are self-sealing, fill two tubes by inserting the end opposite the sealed end into the well mixed EDTA blood sample.
  8. When the self-sealing capillary tubes are two thirds to three fourths filled, tilt them upright causing the blood sample to flow down the tube and come into contact with the sealant.
  9. Continue to hold the tube vertical when the blood makes contact with the sealant for an additional 15 seconds.
    Purpose

    Duplicates should always be done as a means of quality control. Tubes are not filled completely to provide space for the sealing clay.

  10. Wipe the outside of the tubes with clean gauze without touching the wet open end of the tube.
    Purpose

    Wiping the outside of the capillary tube removes any blood. Touching the blood inside the capillary tube with absorbent material removes more plasma than blood cells and can alter the hematocrit.

  11. Place the tubes opposite each other in the centrifuge with the sealed ends securely against the gasket.
    Purpose

    The centrifuge must always be balanced to prevent damage. If the clay ends of the capillary tubes are not outer-most against the gasket, the sample will spin out of the tubes, contaminating the centrifuge.

  12. Note the numbers on the centrifuge slots and record the numbers on the log sheet along with the patient's name.
    Purpose

    The sample must be identified throughout the entire procedure.

  13. Secure the locking top, fasten the lid down, and lock it.
    Purpose

    If the locking top is not firmly in place during the spinning cycle, the tubes will come out of their slots and break. The lid is always locked during centrifugation for safety purposes; that is, to prevent ejection of aerosols or broken glass.

  14. Set the timer and adjust the speed as needed.
    Purpose

    The prescribed time is 3 to 5 minutes at 11,000 to 12,000 rpm. Check the manufacturer's instructions for time and speed.

  15. Allow the centrifuge to come to a complete stop.
  16. Unlock the outer locking top and then remove the inner lid.
    Purpose

    Opening the centrifuge before it has stopped could result in harm to the user.

  17. Remove the tubes immediately and read the results. If this is not possible, store the tubes in an upright position.
    Purpose

    Tubes left in the centrifuge will show altered results because the red blood cell (RBC) layer will spread out horizontally.

  18. Determine the microhematocrit values using one of the following methods: Centrifuge without a built-in reader - Carefully remove the tubes from the centrifuge. Place a tube on the microhematocrit reader. Align the clay-RBC junction with the zero line on the reader. Align the plasma meniscus with the 100% line. The value is read at the junction of the red cell layer and the buffy coat. The buffy coat is not included in the reading. Read both tubes. The average of the two results is reported. The two values should not vary by more than 2%.
  19. Determine the microhematocrit values using one of the following methods: Centrifuge with built-in reader using calibrated capillary tubes - Position the tubes as directed by the manufacturer's instructions. Read both tubes. The average of the two results is reported. The two values should not vary by more than 2%.
  20. Dispose of the capillary tubes in the sharps container.
  21. Disinfect the work area and properly dispose of all biohazardous materials.
  22. Remove your lab coat, gloves, and eyewear and sanitize your hands.
    Purpose

    To ensure infection control.

  23. Record the results in the Hematocrit Patient Log and document the results in the patient's medical record.
    Purpose

    A procedure is not considered done until it is recorded.

Module L27-02 · Procedural skill

CLIA-waived Hemoglobin

Goal: To determine accurately the level of hemoglobin present in a blood sample using the HemoCue B-Hemoglobin System.

Equipment
  • Patient's health record
  • Provider's order and/or lab requisition
  • Hemoglobin laboratory log
  • HemoCue
  • HemoCue microcuvette
  • Autolet or blood lancet
  • Alcohol prep pads
  • Gauze squares
  • Fluid-impermeable lab coat
  • Disposable gloves
  • Biohazard waste and sharps containers
  1. Perform an instrument quality control check by inserting the control cuvette into the instrument. Make sure the reading is within acceptable limits before proceeding.
  2. Sanitize your hands. Put on fluid-impermeable lab coat and disposable gloves.
  3. Assemble all equipment and supplies needed.
  4. Greet the patient and verify his or her identity using two identifiers (e.g., have the patient spell the last name, state the birth date, and/or show a picture ID).
  5. Explain the procedure to the patient.
  6. Examine the patient's fingers and choose the site to be used to obtain the blood sample.
  7. Clean the site with alcohol or another recommended antiseptic preparation.
  8. Perform a capillary puncture and wipe away the first drop of blood.
  9. Obtain a large drop of blood on the surface of the finger.
  10. Touch the microcuvette to the drop of blood. Do not touch the finger. The correct volume is drawn into the cuvette by capillary action. Wipe off any excess blood from the sides of the cuvette.
  11. Place the cuvette in the cuvette holder and insert it into the instrument.
  12. Read the result and record it in the lab's hemoglobin log and the patient's health record.
  13. Turn off the instrument. Dispose of biohazardous waste in the correct containers and properly disinfect the work area.
  14. Remove gloves and dispose in biohazard waste. Remove lab coat and sanitize your hands.
Practice quiz · verbatim from MedCerts

Knowledge-check items

Click an answer to lock it in — you'll see the rationale below. Reset any time to re-attempt. Items originally formatted as true/false, fill-in-blank, or drag-and-drop have been normalized to multiple choice; the source format is noted in the eyebrow.

L27-01 · CLIA-waived Microhematocrit

Q1 · L27-01 · normalized from fitb
A procedure is not considered __________ until it is recorded.
Rationale
"A procedure is not considered done until it is recorded."

This principle establishes that documentation is a required, integral part of any clinical procedure and cannot be omitted or considered optional.

Source: L27-01 Knowledge Check
Q2 · L27-01 · normalized from fitb
With use of the centrifuge, it must always be __________, with a tube on each side, to prevent damage.
Rationale
"The centrifuge must always be balanced to prevent damage."

Proper tube placement on opposite sides ensures equal weight distribution during centrifugation, preventing mechanical stress or failure of the equipment.

Source: L27-01 Knowledge Check
Q3 · L27-01 · normalized from fitb
Once tubes have been inserted, the centrifuge must be secured by fastening the lid down and __________ it.
Rationale
"If the locking top is not firmly in place during the spinning cycle, the tubes will come out of their slots and break. The lid is always locked during centrifugation for safety purposes; that is, to prevent ejection of aerosols or broken glass."

Locking the lid is a critical safety measure that prevents equipment failure and protects the user from exposure to biological hazards.

Source: L27-01 Knowledge Check
Q4 · L27-01 · normalized from fitb
The prescribed time to centrifuge a microhematocrit sample is __________ to 5 minutes.
Rationale
"The prescribed time is 3 to 5 minutes at 11,000 to 12,000 rpm."

This specific time range ensures complete separation of blood cells from plasma without damaging cellular components or altering the hematocrit reading.

Source: L27-01 Knowledge Check

L27-02 · CLIA-waived Hemoglobin

Q1 · L27-02 · normalized from tf
Once the hemoglobin test is completed, the result should be recorded in the lab's hemoglobin log and the patient's health record.
Rationale
"Read the result and record it in the lab's hemoglobin log and the patient's health record."

Both documentation locations are required to maintain proper laboratory records and to ensure the patient's clinical information is available in their medical record.

Source: L27-02 Knowledge Check
Q2 · L27-02 · normalized from tf
An instrument quality control check is performed before the procedure to ensure that only instruments recording values within acceptable control limits are used for patient testing.
Rationale
"Perform an instrument quality control check by inserting the control cuvette into the instrument. Make sure the reading is within acceptable limits before proceeding."

Quality control testing validates instrument accuracy prior to patient sample analysis, ensuring reliable and trustworthy test results.

Source: L27-02 Knowledge Check
Q3 · L27-02 · normalized from tf
If the quality control check reveals a value outside the control limits, the procedure should be continued, and the out-of-range value should be noted in the patient's record.
Rationale
"Perform an instrument quality control check by inserting the control cuvette into the instrument. Make sure the reading is within acceptable limits before proceeding."

A failed quality control check indicates the instrument is not functioning reliably and must not be used for patient testing; proceeding would compromise test accuracy and patient care.

Source: L27-02 Knowledge Check
Q4 · L27-02 · normalized from tf
Prior to the hemoglobin procedure, the patient should be greeted and identity verified using a minimum of how many identifiers?
Rationale
"Greet the patient and verify his or her identity using two identifiers (e.g., have the patient spell the last name, state the birth date, and/or show a picture ID)."

Two identifiers are the standard for safe patient identification in clinical practice to prevent specimen mix-ups and ensure results are attributed to the correct patient.

Source: L27-02 Knowledge Check
Q5 · L27-02 · normalized from tf
The capillary puncture site used to collect the blood sample must be free of trauma, calluses, and scarring.
Rationale
"Examine the patient's fingers and choose the site to be used to obtain the blood sample."

Selecting an appropriate puncture site free of trauma or calluses ensures adequate blood flow and an uncontaminated specimen that will produce accurate hemoglobin results.

Source: L27-02 Knowledge Check