🚧 Under construction — VoTechWorks is being built. A free tech program — complimentary, as our commitment to get America working.
voTechWorksGrade 13 · a vocational technology learning center, by urbanicity
newSchoolWorks.com › VoTechWorks › Health & Personal Services › Phlebotomy Technician › Clinical Practicum: Supervised Phlebotomy Externship › Lesson 3
HLT-PHLE88-06 · Lesson 3 · 24 clock hours · field

Specimen Processing, Special Procedures, and Laboratory Support

Objective. The student performs specimen processing tasks—centrifugation, aliquoting, accessioning, and routing—and assists with at least one special collection type (timed glucose, blood culture, or therapeutic drug monitoring as site volume allows), following site SOPs and stability requirements throughout.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed clinician in the field or by a certification or approval body. It is a study draft and may contain errors. Do not use it to make decisions about any patient or medication. Always follow your instructor, your supervising professional, and current official references and regulations.

VoTechWorks program approval and accreditation are still in progress. Credentials are issued only by the certifying bodies named in each program, after their own exams.

Specimen Processing, Special Procedures, and Laboratory Support

Once a specimen leaves the patient's arm, your responsibility does not end. Correct processing is just as critical as correct collection. A perfectly drawn tube can be ruined by improper centrifugation, mislabeling during aliquoting, or a missed stability window. This lesson covers the core processing tasks you will perform or assist with during your externship, along with the special collection types you may encounter at your site.

Centrifugation

Centrifugation separates blood into its components—serum or plasma on top, the buffy coat (white cells and platelets) in the middle, and red cells at the bottom. Your site SOP will specify the exact speed (expressed in relative centrifugal force, or RCF/×g), time, and brake setting for each tube type. Follow those numbers precisely; incorrect speed or time causes incomplete separation or hemolysis.

Before loading the centrifuge, balance opposite buckets with tubes of equal weight. After the run, inspect each tube:

Never open a centrifuge lid while it is spinning. If you hear unusual noise or vibration, stop the run and notify your supervisor.

Aliquoting

Aliquoting means transferring a measured portion of processed specimen into secondary tubes for routing to different departments (chemistry, immunology, send-out reference lab, etc.). Use a calibrated pipette or transfer pipette specified by the SOP. Cap all aliquot tubes immediately. Label every aliquot with the same patient identifiers as the primary tube before the tube leaves your hands. Cross-contamination between specimens is a serious patient-safety error—change pipette tips between specimens and work one patient at a time.

Accessioning

Accessioning registers the specimen in the laboratory information system (LIS) and creates a chain of custody from collection to result. When accessioning, verify that each of the following matches between the physical label and the LIS record:

1. Patient full name and date of birth (or second identifier per site policy)

2. Medical record number or accession number

3. Test code(s) ordered

4. Collection date and time

5. Collector ID

A discrepancy—any mismatch—must be resolved before the specimen is processed further. During your competency check your supervisor will plant one intentional error. Treat that exercise as you would a real event: identify the discrepancy, document it on the case log, and correct it under supervisor direction before releasing the specimen.

Routing and Stability

After processing and accessioning, specimens are routed to the appropriate bench or sent to a reference laboratory. Stability requirements govern how long a specimen remains usable at a given temperature. Common rules include keeping certain hormone assays chilled on wet ice from collection through processing, and protecting bilirubin samples from light. Your site SOP binder or digital portal is the authoritative source—never guess at stability requirements.

Special Collection Types

Blood cultures: Collected using strict aseptic technique to prevent contamination. Skin antisepsis—typically with chlorhexidine or a two-step iodine method per site protocol—is rigorous. Bottles are inoculated in a specific order (aerobic first from syringe method, per site SOP), incubated, and monitored for growth. Even observing this draw teaches you contamination-prevention principles that apply throughout phlebotomy.

Oral Glucose Tolerance Test (OGTT): Requires timed draws at defined intervals after the patient ingests a standardized glucose solution. Patient preparation (fasting period, activity restrictions) and precise timing are essential—a draw even a few minutes early or late can invalidate the result. Label each tube with the exact collection time.

Therapeutic Drug Monitoring (TDM): Drug levels (such as for certain antibiotics or anticonvulsants) must be drawn at a defined trough or peak time relative to the dose. Confirm the dose time with nursing before collecting. Document the actual draw time accurately.

Chain-of-custody collections (e.g., paternity or forensic drug testing): Every step is documented with signatures, seals, and unbroken custody. An error in documentation can invalidate a legal result. Follow the site's chain-of-custody form exactly.

Procedure Summary Assignment

For at least one special collection type you participate in or observe, you will write a procedure summary using the provided template. Your summary must describe patient preparation, timing requirements, labeling instructions, and transport or stability requirements specific to that collection. The program coordinator will grade it on accuracy of steps (50%), identification of patient safety checkpoints (30%), and professional writing (20%). A score of 75% or higher is required to pass.

Professional Conduct in the Processing Area

The laboratory is a regulated environment. Wear your PPE at all times when handling specimens. Never eat, drink, or apply cosmetics in the processing area. Log off LIS terminals when you step away. If you are unsure of a SOP step, ask before acting—a delayed question is far safer than an incorrect action on a patient specimen.

Key terms10

CentrifugationThe process of spinning blood tubes at a defined speed and time to separate components—serum or plasma, buffy coat, and red cells—for laboratory analysis.
Relative centrifugal force (RCF / ×g)The standardized unit used to express centrifuge speed, accounting for rotor radius; preferred over RPM because it is consistent across machines.
AliquotingTransferring a measured portion of a processed primary specimen into one or more secondary labeled tubes for routing to different laboratory departments.
AccessioningThe process of entering a specimen into the laboratory information system (LIS), assigning a unique identifier, and verifying that patient demographics and test orders match the physical label.
HemolysisRupture of red blood cells releasing hemoglobin into serum or plasma, recognized by pink or red discoloration; interferes with many laboratory tests and is a common reason for specimen rejection.
LipemiaMilky or turbid appearance of serum or plasma caused by elevated lipid content; can interfere with photometric assays and may be related to a patient's recent food intake.
Specimen stabilityThe defined conditions (temperature, light exposure, time) under which a specimen maintains analyte integrity sufficient for accurate testing; specified in the site SOP for each test.
Chain of custodyA documented, unbroken record of who collected, handled, transferred, and tested a specimen, required for legal or forensic samples to ensure result validity.
Trough levelIn therapeutic drug monitoring, the specimen collected immediately before the next scheduled dose, representing the lowest drug concentration in the dosing cycle.
Laboratory information system (LIS)The software platform used by clinical laboratories to receive test orders, track specimens, record results, and communicate with the electronic health record.

Worked examples4

1. A site SOP requires a serum separator tube (SST) to be centrifuged at 1,500 × g for 10 minutes. The centrifuge display shows RPM, not RCF. The rotor has a radius of 15 cm. Convert 1,500 × g to RPM using the formula: RPM = 1,000 × √(RCF / (1.118 × r)), where r is the radius in centimeters.
  1. Identify values: RCF = 1,500; r = 15 cm; constant = 1.118.
  2. Multiply the constant by the radius: 1.118 × 15 = 16.77.
  3. Divide RCF by that product: 1,500 ÷ 16.77 ≈ 89.45.
  4. Take the square root of 89.45: √89.45 ≈ 9.46.
  5. Multiply by 1,000: 9.46 × 1,000 ≈ 9,460 RPM.
  6. Set the centrifuge to approximately 9,460 RPM to achieve 1,500 × g with this rotor.
Answer: Approximately 9,460 RPM achieves 1,500 × g on a centrifuge with a 15 cm rotor radius.
2. An OGTT requires fasting baseline, then draws at exactly 1 hour and 2 hours after the patient finishes the glucose drink. The patient finishes the drink at 08:14. At what clock times must the 1-hour and 2-hour draws be collected?
  1. Record the finish time: 08:14.
  2. Add 60 minutes for the 1-hour draw: 08:14 + 1:00 = 09:14.
  3. Add 120 minutes for the 2-hour draw: 08:14 + 2:00 = 10:14.
  4. Label each tube with the patient name, date of birth, collector ID, and the exact scheduled and actual collection time for that interval.
Answer: The 1-hour draw must be collected at 09:14 and the 2-hour draw at 10:14. Actual collection time must be recorded on each tube label and in the LIS.
3. During accessioning you compare a tube label to the LIS record and find the following: Label reads DOB 03/15/1987; LIS shows DOB 03/15/1978. The patient name and MRN match. Describe the correct response.
  1. Stop—do not process or route the specimen.
  2. Flag the discrepancy: the date of birth on the label does not match the LIS record (1987 vs. 1978).
  3. Notify your supervisor immediately and document the discrepancy on the case log with the time discovered.
  4. Under supervisor direction, check the original order, patient wristband, or registration record to determine which date of birth is correct.
  5. Correct the erroneous field in the LIS or on the label per site SOP—do not alter a physical label yourself unless your site policy and supervisor authorize it.
  6. Document the corrective action taken and initial the case log entry.
Answer: The specimen must be held and the date-of-birth discrepancy resolved with supervisor guidance before the specimen is processed, to prevent a patient identification error that could cause a wrong result to be reported.
4. You aliquot 1 mL of serum into each of three secondary tubes from a primary SST that yielded 4.5 mL of serum. After aliquoting, how much serum remains in the primary tube, and is there enough to save as a hold specimen if the site requires a minimum 0.5 mL hold volume?
  1. Calculate volume removed: 3 aliquots × 1 mL each = 3 mL removed.
  2. Subtract from the total: 4.5 mL − 3.0 mL = 1.5 mL remaining.
  3. Compare to the minimum hold volume: 1.5 mL > 0.5 mL minimum.
  4. Conclusion: Yes, 1.5 mL remains in the primary tube, which exceeds the 0.5 mL minimum hold requirement.
Answer: 1.5 mL of serum remains in the primary tube after aliquoting, which is sufficient to meet a 0.5 mL minimum hold volume requirement.

The math in this lesson1

Learners rearrange the RCF formula to solve for centrifuge RPM, including a square root.
A-CED.4
Brush up in the math halls at newSchoolWorks.com:
In class: Process a minimum number of centrifuge runs during the practicum, checking speed, time, and brake settings per the site SOP; inspect for hemolysis, lipemia, and adequate volume; document rejection criteria applied to any rejected specimen and the corrective action taken on the case log. · Participate in or observe at least one blood culture collection or other special draw type available at the site (OGTT timed draws, paternity chain-of-custody, therapeutic phlebotomy, or pediatric micro-collection); write a procedure summary describing patient prep, timing, labeling, and transport requirements specific to that collection. · Accession five or more specimens into the site LIS or requisition system under supervisor oversight, verifying that demographic data, test codes, collection time, and collector ID match the physical label; identify and correct one intentional discrepancy planted by the supervisor as a competency check.
Materials: Site centrifuge, aliquot tubes, pipettes, biohazard bags, transport coolers or warmers as required, LIS terminals or paper requisition forms, blood culture bottles (observation only if not a site-assigned task), site SOP binder or digital SOP portal, procedure summary template
Check: Procedure summary graded by program coordinator using a rubric: accuracy of steps described (50%), identification of patient safety checkpoints (30%), professional writing (20%); pass = 75% total. LIS discrepancy exercise: student must identify and document the planted error before submitting the specimen. Case log centrifuge entries reviewed for completeness at final evaluation.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Specimen Handling and Processing
1. After centrifuging a serum separator tube, you notice the serum has a pink tint. Which term best describes this finding, and what is the most likely cause?
Specimen Handling and Processing
2. A site SOP requires centrifuging a plasma tube at 2,000 × g for 15 minutes with a low brake setting. A student uses the same speed and time but sets the brake to high. What is the most likely consequence?
Specimen Handling and Processing
3. When accessioning a specimen, you compare the tube label to the LIS order and discover the collection time on the label reads 07:30 but the LIS shows 10:15. What is the correct immediate action?
Special Collection Procedures
4. A patient is scheduled for a 2-hour oral glucose tolerance test. The patient finishes the glucose drink at 09:22. At what time should the 2-hour specimen be collected?
Special Collection Procedures
5. Which of the following best describes the purpose of a chain-of-custody procedure in specimen collection?
Specimen Handling and Processing
6. You are aliquoting serum from a primary tube that contains 3.0 mL of serum into two secondary tubes requiring 1.2 mL each. After aliquoting, how much serum remains in the primary tube?
Special Collection Procedures
7. A therapeutic drug monitoring trough level is ordered for a patient receiving a twice-daily anticonvulsant. Before collecting the specimen, what information is most important to confirm?
Special Collection Procedures
8. During a blood culture collection observation, you notice the phlebotomist cleaning the venipuncture site but skipping the required contact time for the antiseptic agent. What is the primary patient safety risk of this error?
Record this lesson on my transcript. Sign in with your key and enrollment email to record lessons (enroll free if you have no key). This page stays open to read and practise.
← Previous lessonProgram planNext lesson →