Medical Laboratory Scientist (MLS) Examination — ASCP Board of Certification — Questions and Answers

Question 1: When using a refractometer to measure urine specific gravity, the instrument measures:

pH of the urine
The refractive index, which correlates with solute concentration (Correct answer)
The electrical conductivity of the sample
Osmolality directly

Correct answer: The refractive index, which correlates with solute concentration

A refractometer measures how much light bends (refractive index) as it passes through the sample, which correlates with dissolved solute concentration and specific gravity.

Question 2: Which term means the study of tissues?

Pathology
Hematology
Histology (Correct answer)
Cytology

Correct answer: Histology

Histology (histo- = tissue, -logy = study of) is the microscopic study of tissue structure.

Question 3: Which diagnostic test is commonly used to detect bacterial infections in the bloodstream?

Lipid Profile
Blood Culture (Correct answer)
Complete Blood Count (CBC)
Serum Electrolyte Panel

Correct answer: Blood Culture

A blood culture is the gold standard diagnostic test for detecting bacterial or fungal infections in the bloodstream, a condition known as bacteremia or septicemia. Blood samples are collected and incubated in a nutrient-rich medium to allow any present microorganisms to grow. Positive cultures can then be identified, and their susceptibility to antibiotics can be determined, guiding appropriate treatment.

Question 4: A positive DAT (direct antiglobulin test) with anti-IgG reagent, combined with a negative DAT with anti-C3d, is most consistent with:

Hemolytic disease of the fetus and newborn
Paroxysmal cold hemoglobinuria
Cold agglutinin disease
Drug-induced immune hemolytic anemia or warm autoimmune hemolytic anemia (Correct answer)

Correct answer: Drug-induced immune hemolytic anemia or warm autoimmune hemolytic anemia

Warm AIHA and many drug-induced cases coat red cells with IgG without complement deposition, producing a positive anti-IgG DAT and negative anti-C3d DAT.

Question 5: The root 'osteo-' refers to:

Joint
Ligament
Bone (Correct answer)
Cartilage

Correct answer: Bone

Osteo- means bone, as in osteocyte (bone cell), osteoporosis, or osteomyelitis.

Question 6: Which skill is most important for success in Medical Terminology & Anatomy within Medical Laboratory Scientist?

Working without any training
Continuous learning and adaptation (Correct answer)
Resisting change
Avoiding feedback

Correct answer: Continuous learning and adaptation

Continuous learning ensures professionals stay current with evolving practices in Medical Terminology & Anatomy.

Question 7: Which blood group system, beyond ABO and Rh, is most notorious for causing severe delayed hemolytic transfusion reactions (DHTRs)?

Kidd (Jk) system (Correct answer)
P1PK system
Lewis system
MNS system

Correct answer: Kidd (Jk) system

Kidd (Jk) system antibodies are clinically significant because they can rapidly drop to undetectable levels, then rebound upon re-exposure causing severe, potentially fatal DHTRs that are difficult to anticipate.

Question 8: Which element on a laboratory requisition form is MOST critical for routing a specimen to the correct testing department?

Patient's preferred language
Test(s) ordered and specimen type (Correct answer)
Patient's insurance provider
Ordering physician's NPI number

Correct answer: Test(s) ordered and specimen type

The test ordered and specimen type determine which department receives and processes the specimen, making them the most operationally critical elements.

Question 9: A laboratory uses Westgard rules. A 1-3s warning rule is triggered on a quality control chart. The appropriate action is:

Reject the run and investigate immediately
Repeat the QC sample once and reject if still out
Halt all patient testing pending supervisor review
Accept the run but investigate for a possible trend (Correct answer)

Correct answer: Accept the run but investigate for a possible trend

The 1-3s rule is a warning rule only; the run should be accepted but reviewed for emerging trends, and the 1-2s or multi-rule pattern assessed before rejecting.

Question 10: When reporting a Pap smear result using the Bethesda System, the term 'NILM' indicates:

Negative for intraepithelial lesion or malignancy (Correct answer)
No squamous cells present
Non-invasive low-grade malignancy
Needs immediate liquid-based cytology repeat

Correct answer: Negative for intraepithelial lesion or malignancy

NILM stands for Negative for Intraepithelial Lesion or Malignancy, meaning the cervical sample shows no cytologic evidence of a precancerous or cancerous process.

Question 11: A urine culture grows >100,000 CFU/mL of E. coli. The MLS should perform susceptibility testing using which reference method standard for Enterobacteriaceae?

Kirby-Bauer with manufacturer-defined zones only
EUCAST breakpoints only
Etest with NCCLS 1999 breakpoints
CLSI broth microdilution or disk diffusion with current CLSI breakpoints (Correct answer)

Correct answer: CLSI broth microdilution or disk diffusion with current CLSI breakpoints

CLSI broth microdilution or disk diffusion using current CLSI M100 breakpoints is the US standard for susceptibility testing of Enterobacteriaceae.

Question 12: What does the term 'resolution' refer to when describing a centrifuge's performance?

Temperature control accuracy
Volume capacity of the rotor
Maximum RPM achievable
Ability to separate two particles of different sedimentation rates (Correct answer)

Correct answer: Ability to separate two particles of different sedimentation rates

Resolution in centrifugation refers to how well the instrument can separate two populations of particles with different densities or sizes.

Question 13: Which of the following best describes confidentiality in Medical Laboratory Scientist?

Keeping all information secret permanently
Protecting sensitive information from unauthorized disclosure (Correct answer)
Sharing information freely with everyone
Only sharing information verbally

Correct answer: Protecting sensitive information from unauthorized disclosure

Confidentiality involves protecting sensitive information and only sharing it with authorized parties who need it.

Question 14: Which skill is most important for success in Emergency Procedures & Response within Medical Laboratory Scientist?

Resisting change
Avoiding feedback
Working without any training
Continuous learning and adaptation (Correct answer)

Correct answer: Continuous learning and adaptation

Continuous learning ensures professionals stay current with evolving practices in Emergency Procedures & Response.

Question 15: A laboratory receives a blood culture bottle that has been incubating for 5 days with no growth signal. What is the standard reporting outcome?

Report 'No growth at 5 days' and discard (Correct answer)
Perform Gram stain immediately
Report 'No growth at 72 hours'
Sub-culture to solid media and incubate another 5 days

Correct answer: Report 'No growth at 5 days' and discard

Standard blood culture incubation is 5 days; bottles with no instrument signal at that point are reported as 'No growth at 5 days' and discarded per protocol.

Question 16: Which safety practice is essential for preventing cross-contamination in Medical Laboratory Scientist?

Proper hand hygiene and equipment sanitation (Correct answer)
Skipping cleaning protocols
Working faster
Using the same tools everywhere

Correct answer: Proper hand hygiene and equipment sanitation

Proper hygiene and sanitation prevent the transfer of harmful agents between surfaces, materials, or patients.

Question 17: An IQCP (Individualized Quality Control Plan) allows a laboratory to:

Reduce test menu offerings to lower QC burden
Eliminate all external QC requirements under CLIA
Replace proficiency testing with internal audits
Customize QC frequency and type based on a risk assessment of the testing process (Correct answer)

Correct answer: Customize QC frequency and type based on a risk assessment of the testing process

IQCP enables laboratories to design a quality control plan tailored to their specific testing process by conducting a risk assessment covering specimen, test system, and testing environment.

Question 18: What is the role of mentoring in Medical Laboratory Scientist professional development?

Evaluating performance for promotions
Monitoring employee attendance
Guiding and supporting professional growth through experience sharing (Correct answer)
Telling employees exactly what to do

Correct answer: Guiding and supporting professional growth through experience sharing

Mentoring provides guidance and support by sharing knowledge and experience, helping mentees develop professionally.

Question 19: A Neubauer hemocytometer counting chamber has a depth of:

0.1 mm (Correct answer)
0.5 mm
0.01 mm
1.0 mm

Correct answer: 0.1 mm

The standard Neubauer hemocytometer has a chamber depth of 0.1 mm, which is used in calculating cell counts per volume.

Question 20: A laboratory's social media policy prohibits posting patient information online. An MLS posts a 'funny' lab result (with no name) from a patient's chart. This action:

Is permissible because no name was included
Still violates HIPAA if the result could identify the patient in context (Correct answer)
Is only a policy violation, not a legal issue
Is acceptable if shared only with other laboratory professionals

Correct answer: Still violates HIPAA if the result could identify the patient in context

Even de-identified information can constitute a HIPAA violation if the combination of details could reasonably identify a patient.

Question 21: Which of the following is a pre-analytical variable that the MLS can identify from the patient assessment before collection?

Spectrophotometer wavelength drift
Instrument calibration error
Patient exercise within 30 minutes of collection (Correct answer)
Incorrect reagent lot

Correct answer: Patient exercise within 30 minutes of collection

Recent strenuous exercise is a pre-analytical variable affecting analytes like CK, potassium, and lactate that can be identified during patient assessment.

Question 22: Which quality control material is used to verify that a laboratory test is performing correctly at a concentration near the medical decision level?

Control material (QC) (Correct answer)
Calibrator
Reference material
Reagent blank

Correct answer: Control material (QC)

Control materials are independent samples with known (or target) values run alongside patient samples to monitor ongoing assay performance.

Question 23: During a code blue near the laboratory, an MLS discovers a patient unresponsive. Per standard protocol, what should be the first action?

Begin chest compressions immediately
Call for help and activate the emergency response system (Correct answer)
Administer two rescue breaths
Retrieve the AED from the hallway

Correct answer: Call for help and activate the emergency response system

Activating the emergency response system ensures trained personnel and resources respond, which is the priority before solo intervention.

Question 24: Which risk response strategy involves transferring risk to a third party in Medical Laboratory Scientist?

Avoidance
Mitigation
Acceptance
Transfer (e.g., insurance) (Correct answer)

Correct answer: Transfer (e.g., insurance)

Risk transfer shifts the financial or operational impact of a risk to another party, commonly through insurance or contracts.

Question 25: A 2+ positive direct antiglobulin test (DAT) is found on a routine pretransfusion sample. This finding is MOST consistent with:

ABO incompatibility from a prior transfusion error
Reagent contamination with anti-IgG
A cold agglutinin active only at room temperature
IgG antibody or complement coating the patient's RBCs in vivo (Correct answer)

Correct answer: IgG antibody or complement coating the patient's RBCs in vivo

A positive DAT indicates IgG antibodies or complement components (C3d) are coating patient RBCs in vivo, which can occur in AIHA, HDN, or drug-induced hemolysis.

Question 26: What does a corrected reticulocyte count (reticulocyte production index, RPI) below 2 indicate?

Adequate bone marrow response to anemia
Polycythemia vera with erythroid hyperplasia
Hemolytic process with increased RBC destruction
Hypoproliferative or ineffective erythropoiesis (Correct answer)

Correct answer: Hypoproliferative or ineffective erythropoiesis

An RPI <2 suggests the bone marrow is not producing enough red cells to compensate for anemia, pointing to hypoproliferative or ineffective erythropoiesis.

Question 27: An HIV-1/2 antigen/antibody combination (4th-generation) immunoassay is reactive. The confirmatory algorithm's next step is:

HIV-1/HIV-2 antibody differentiation immunoassay (Correct answer)
Repeat the same 4th-generation assay in duplicate
Western blot for HIV-1 only
CD4+ T-cell count

Correct answer: HIV-1/HIV-2 antibody differentiation immunoassay

Current CDC/APHL guidelines recommend an HIV-1/HIV-2 antibody differentiation immunoassay as the second step following a reactive 4th-generation combination test to distinguish HIV-1 from HIV-2 infection.

Question 28: A patient's electronic order requires a 'timed specimen' for cortisol at 0800. The MLS collects the specimen at 0830. What is the correct action?

Discard the specimen and collect a new one the following morning
Change the documented time to 0800 to match the order
Document the actual collection time as 0830 and notify the provider of the delay (Correct answer)
Process the specimen without documenting the time discrepancy

Correct answer: Document the actual collection time as 0830 and notify the provider of the delay

The actual collection time must always be documented accurately; the provider should be notified of the 30-minute delay so they can determine if the result is still clinically useful.

Question 29: Which laboratory test is commonly used to assess thyroid function?

Erythrocyte Sedimentation Rate (ESR)
Blood Urea Nitrogen (BUN)
Thyroid-Stimulating Hormone (TSH) (Correct answer)
C-reactive Protein (CRP)

Correct answer: Thyroid-Stimulating Hormone (TSH)

Thyroid-Stimulating Hormone (TSH) is the primary screening test for assessing thyroid function because it reflects how well the pituitary gland is stimulating the thyroid gland. Elevated TSH levels typically indicate an underactive thyroid (hypothyroidism), while low TSH levels suggest an overactive thyroid (hyperthyroidism). This test provides a sensitive and early indicator of thyroid dysfunction, guiding further diagnostic steps.

Question 30: Under CLSI and CAP guidelines, how often must laboratory emergency evacuation drills be conducted at minimum?

Every two years
Quarterly
Annually (Correct answer)
Monthly

Correct answer: Annually

Most accrediting bodies including CAP require at minimum annual fire/evacuation drills to ensure staff familiarity with emergency procedures.

Question 31: A new rapid influenza test is being evaluated against viral culture. Sensitivity is 70% and specificity is 99%. What does the low sensitivity mean in practice?

The test produces many false positives in flu-positive patients
The test is unreliable for ruling in influenza
30% of true influenza cases will test negative (false negatives) (Correct answer)
Culture is less accurate than the rapid test

Correct answer: 30% of true influenza cases will test negative (false negatives)

Sensitivity of 70% means 30% of patients who truly have influenza will receive a false-negative result and may go undiagnosed and untreated.

Question 32: A laboratory thermometer reads 37.2°C when placed in a 37.0°C reference bath. This difference is best described as:

Random error
Systematic error (bias) (Correct answer)
Precision failure
Analytical sensitivity issue

Correct answer: Systematic error (bias)

A consistent offset from the true value in one direction is systematic error (bias), which can often be corrected by calibration.

Question 33: A hemoglobin electrophoresis at alkaline pH shows a band migrating to the S position. Which confirmatory test best differentiates HbS from HbD?

Reticulocyte count
Heinz body preparation
Acid electrophoresis (pH 6.2) (Correct answer)
Osmotic fragility test

Correct answer: Acid electrophoresis (pH 6.2)

Acid electrophoresis separates HbS from HbD because HbD migrates with HbA at acid pH while HbS remains in the S position, confirming the identity of the variant.

Question 34: Which of the following BEST describes 'total allowable error' (TEa)?

The difference between two method means
The sum of all QC failures in a month
The acceptable range for proficiency testing scores
The maximum permissible combination of bias and imprecision for an analyte (Correct answer)

Correct answer: The maximum permissible combination of bias and imprecision for an analyte

TEa defines the maximum error a method can produce and still yield clinically acceptable results, incorporating both systematic bias and random imprecision.

Question 35: Which microscopy technique uses oblique illumination to produce a three-dimensional appearance without staining, making it ideal for viewing unstained wet preparations?

Brightfield microscopy
Darkfield microscopy
Phase contrast microscopy (Correct answer)
Fluorescence microscopy

Correct answer: Phase contrast microscopy

Phase contrast microscopy converts phase shifts in light passing through transparent specimens into visible brightness changes, allowing visualization of unstained cells.

Question 36: The prefix 'hepato-' refers to which organ?

Spleen
Pancreas
Kidney
Liver (Correct answer)

Correct answer: Liver

Hepato- derives from the Greek 'hepar' meaning liver, as in hepatocyte or hepatitis.

Question 37: The term 'erythrocyte' literally translates to:

Platelet
Red cell (Correct answer)
White cell
Large cell

Correct answer: Red cell

Erythro- means red and -cyte means cell, so erythrocyte = red blood cell.

Question 38: In the event of an earthquake during a laboratory shift, what action should MLS personnel take if unable to evacuate?

Stand in a doorframe for structural protection
Drop to the floor, take cover under a sturdy surface, and hold on (Correct answer)
Run to the nearest exit immediately during shaking
Attempt to secure open chemical containers before taking cover

Correct answer: Drop to the floor, take cover under a sturdy surface, and hold on

Drop, Cover, and Hold On is the evidence-based earthquake response protocol, as doorframes offer no special protection in modern buildings.

Question 39: A patient with septic shock has a lactate of 6.8 mmol/L at initial presentation. After 6 hours of aggressive fluid resuscitation and antibiotics, lactate is 4.1 mmol/L. This trend MOST indicates:

Adequate tissue perfusion restoration; continue current management
Partial response; lactate clearance below the 10% threshold for adequate resuscitation (Correct answer)
Ongoing tissue hypoxia requiring additional fluids
Treatment failure; escalate to vasopressors immediately

Correct answer: Partial response; lactate clearance below the 10% threshold for adequate resuscitation

Surviving Sepsis Campaign guidelines target greater than 10% lactate clearance per hour; a drop from 6.8 to 4.1 (approximately 40% over 6 hours) indicates a partial but meaningful response.

Question 40: A laboratory result is reported with a delta check flag. This means:

The result falls outside the reference interval
The result differs significantly from the patient's previous value (Correct answer)
The analyte is at a critical value level
The specimen was collected in the wrong tube

Correct answer: The result differs significantly from the patient's previous value

A delta check compares the current result to the patient's most recent prior result; a flag indicates a change exceeding the defined limit, alerting staff to possible error or acute clinical change.

Question 41: Which condition is MOST likely if osmotic fragility testing shows increased RBC resistance to hemolysis in hypotonic saline?

Sickle cell disease
Hereditary spherocytosis
Autoimmune hemolytic anemia
Iron deficiency anemia (Correct answer)

Correct answer: Iron deficiency anemia

Iron deficiency produces hypochromic, microcytic RBCs with a larger surface-to-volume ratio, making them more resistant to osmotic lysis (decreased fragility).

Question 42: What information is required on a chain of custody form for a forensic or medico-legal specimen?

Only the final receiving laboratory's signature
The patient's social security number and insurance provider
Collector's initials and specimen color only
Each individual who handled the specimen, with date and time of transfer (Correct answer)

Correct answer: Each individual who handled the specimen, with date and time of transfer

Chain of custody requires documentation of every person who handled the specimen, along with dates and times, to ensure specimen integrity for legal purposes.

Question 43: A CSF specimen is received with xanthochromia. This finding is most suggestive of:

Traumatic tap
Subarachnoid hemorrhage that occurred hours to days ago (Correct answer)
Bacterial meningitis
Viral encephalitis

Correct answer: Subarachnoid hemorrhage that occurred hours to days ago

Xanthochromia (yellow discoloration) results from oxyhemoglobin and bilirubin released after red cell lysis and is a hallmark of subarachnoid hemorrhage, typically appearing 2–4 hours after the bleed.

Question 44: In Medical Laboratory Scientist, what is a risk matrix used for?

Evaluating risks based on likelihood and impact (Correct answer)
Scheduling team meetings
Calculating project budgets
Tracking employee performance

Correct answer: Evaluating risks based on likelihood and impact

A risk matrix plots risks on a grid of likelihood versus impact, helping prioritize which risks need the most attention.

Question 45: In Medical Laboratory Scientist, what is a Key Performance Indicator (KPI)?

A compliance checklist
A measurable value that demonstrates effectiveness (Correct answer)
A financial penalty for poor performance
A mandatory training requirement

Correct answer: A measurable value that demonstrates effectiveness

KPIs are quantifiable measurements that demonstrate how effectively objectives are being achieved.

Question 46: A mercury thermometer breaks inside a refrigerator storing patient specimens. What is the correct first step in mercury spill response?

Vacuum up the mercury droplets with a standard laboratory vacuum
Seal the refrigerator and wait for housekeeping to respond
Ventilate the area, don appropriate PPE, and use a mercury spill kit (Correct answer)
Wipe up the mercury with paper towels and discard in biohazard waste

Correct answer: Ventilate the area, don appropriate PPE, and use a mercury spill kit

Mercury vapor is toxic; proper PPE and a mercury-specific spill kit prevent inhalation exposure and environmental contamination.

Question 47: A patient with suspected Ebola virus disease requires laboratory testing. Which containment approach is mandated for specimen handling?

Only urine specimens may be processed; blood collection is prohibited
Processing may occur in any BSL-2 lab with enhanced respiratory protection
Standard precautions with a surgical mask are sufficient
Specimens must be handled using BSL-4 protocols in a designated facility (Correct answer)

Correct answer: Specimens must be handled using BSL-4 protocols in a designated facility

Ebola specimens must be handled under BSL-4 conditions at designated facilities per CDC guidelines due to the extreme infectivity and lethality of the virus.

Question 48: Which Rh antigen is considered the most clinically significant and immunogenic?

Rh E
Rh C
Rh D (Correct answer)
Rh c

Correct answer: Rh D

The D antigen is the most immunogenic of the Rh antigens and is the primary antigen responsible for hemolytic disease of the fetus and newborn (HDFN) and hemolytic transfusion reactions.

Question 49: When should risk assessments be updated in Medical Laboratory Scientist?

Once per year at annual review
Regularly and whenever significant changes occur (Correct answer)
Only at the beginning of a project
Only after an incident happens

Correct answer: Regularly and whenever significant changes occur

Risk assessments should be living documents, updated regularly and whenever there are significant changes in conditions, processes, or scope.

Question 50: During a chemical emergency, MSDS/SDS documentation is critical. Where must SDS sheets be immediately accessible to laboratory workers?

In the department manager's office only
At the hospital security desk for emergency personnel
On the facility intranet, accessible only from administrative computers
In the work area where chemicals are used or stored (Correct answer)

Correct answer: In the work area where chemicals are used or stored

OSHA requires SDS to be readily accessible to employees in their work area during each work shift.

Question 51: An MLS is asked by a friend to look up a mutual acquaintance's recent lab results 'just out of curiosity.' The MLS should:

Share the results if the acquaintance is also a healthcare worker
Decline; accessing records without a treatment purpose violates patient privacy (Correct answer)
Look up the results but not share them with others
Access only the most recent result to minimize the breach

Correct answer: Decline; accessing records without a treatment purpose violates patient privacy

Accessing patient records without a legitimate clinical reason is a HIPAA violation regardless of personal relationships.

Question 52: A specimen is received with no patient name but with a medical record number and date of birth. Per most laboratory policies, this specimen should be:

Processed only for STAT orders
Rejected, because the patient name is always required as one of the two identifiers
Held until the nursing unit provides a corrected label in person
Processed, as two acceptable identifiers are present (Correct answer)

Correct answer: Processed, as two acceptable identifiers are present

Medical record number and date of birth each qualify as acceptable patient identifiers; two valid identifiers are present so the specimen can be processed.

Question 53: What is the primary function of a fume hood in a laboratory?

Measure sample absorbance
Store laboratory chemicals
Protect users from harmful fumes (Correct answer)
Sterilize equipment

Correct answer: Protect users from harmful fumes

A fume hood is a critical safety device in laboratories designed to protect users from exposure to hazardous fumes, vapors, and particulate matter. It works by drawing air from the laboratory into the hood and exhausting it outside, creating a contained workspace. This prevents the inhalation of toxic substances and minimizes the risk of chemical exposure, ensuring a safer working environment.

Question 54: What is the role of documentation in Clinical Procedures & Protocols for Medical Laboratory Scientist?

It should only be done monthly
It provides an accurate record for accountability and reference (Correct answer)
It is only for management review
It is unnecessary paperwork

Correct answer: It provides an accurate record for accountability and reference

Proper documentation in Clinical Procedures & Protocols ensures accountability, traceability, and serves as a reference for future decisions.

Question 55: What does risk mitigation mean in Medical Laboratory Scientist practice?

Taking steps to reduce the likelihood or impact of identified risks (Correct answer)
Eliminating all risks completely
Accepting all risks without action
Ignoring low-level risks

Correct answer: Taking steps to reduce the likelihood or impact of identified risks

Risk mitigation involves implementing strategies to reduce either the probability of a risk occurring or its potential impact.

Question 56: A requisition is received for a drug level with no dose or last dose time listed. Why is this information critical?

Trough vs. peak timing affects therapeutic range interpretation (Correct answer)
It is needed for billing purposes under ICD-10 coding
It is required only for controlled substances by federal law
It determines which tube color to use for collection

Correct answer: Trough vs. peak timing affects therapeutic range interpretation

Knowing the last dose time determines whether a specimen is a trough or peak level, which directly affects whether the drug concentration is within therapeutic range.

Question 57: Which biological safety level (BSL) designation requires both a self-contained suit with a supplied air source and a dedicated decontamination shower?

BSL-4 (Correct answer)
BSL-1
BSL-3
BSL-2

Correct answer: BSL-4

BSL-4 laboratories handle the most dangerous pathogens and require full-body positive-pressure suits with supplied air for maximum worker protection.

Question 58: What is a fundamental principle of Emergency Procedures & Response in Medical Laboratory Scientist practice?

Working in isolation without guidance
Ignoring industry guidelines
Following established standards and best practices (Correct answer)
Using outdated methods

Correct answer: Following established standards and best practices

Following established standards and best practices ensures quality and consistency in Emergency Procedures & Response.

Question 59: When reviewing a patient's medical record prior to phlebotomy, the MLS notes the patient is on warfarin. What is the primary concern for specimen collection?

Warfarin invalidates all coagulation test results
Prolonged bleeding after venipuncture requires extended pressure time (Correct answer)
The anticoagulant may interfere with CBC tube selection
A special transport medium is required for the specimen

Correct answer: Prolonged bleeding after venipuncture requires extended pressure time

Patients on warfarin have prolonged clotting times, so extended pressure must be applied after venipuncture to achieve hemostasis.

Question 60: A fasting glucose specimen is received, but the requisition does not indicate fasting status. What is the appropriate course of action?

Contact the patient or nursing unit to verify fasting status before reporting (Correct answer)
Reject the specimen and order a recollection with fasting documentation
Run the specimen and report results as non-fasting
Add a comment 'fasting status unknown' only if glucose is elevated

Correct answer: Contact the patient or nursing unit to verify fasting status before reporting

Fasting status must be verified and documented because it directly affects the interpretation of fasting glucose results.

Question 61: A patient requests copies of their own laboratory results. Under HIPAA, the laboratory must:

Provide access within 30 days under the HIPAA Right of Access rule (Correct answer)
Deny the request because results are proprietary
Charge an unrestricted fee before releasing any records
Require the ordering physician to release results on the patient's behalf

Correct answer: Provide access within 30 days under the HIPAA Right of Access rule

HIPAA's Right of Access provision requires covered entities to provide patients access to their PHI within 30 days of a request.

Question 62: Which of the following best illustrates the ethical principle of 'justice' in laboratory medicine?

An MLS performs all tests with equal technical rigor regardless of patient demographics (Correct answer)
An MLS prioritizes testing for patients who have better insurance coverage
An MLS expedites tests for patients who are personal acquaintances
An MLS discloses results only to patients who request them personally

Correct answer: An MLS performs all tests with equal technical rigor regardless of patient demographics

Justice requires fair, equitable treatment for all patients without discrimination based on social, economic, or demographic factors.

Question 63: Which of the following infectious waste categories requires incineration or steam sterilization before disposal in a sanitary landfill?

Pathological waste including tissues and body parts (Correct answer)
Expired reagents with no infectious material
Urine specimens in sealed plastic containers
Routine blood collection tubes that are intact

Correct answer: Pathological waste including tissues and body parts

Pathological waste (tissues, body parts, blood) must be treated by incineration or autoclaving before landfill disposal per state and federal regulations.

Question 64: Which reagent in the Wright-Giemsa stain is responsible for staining acidic cellular components pink/red?

Methylene blue
Azure B
Crystal violet
Eosin Y (Correct answer)

Correct answer: Eosin Y

Eosin Y is the acidic dye in Wright-Giemsa that binds to basic (positively charged) cellular components such as hemoglobin and eosinophil granules, staining them pink to red.

Question 65: Which of the following urine findings is most consistent with nephrotic syndrome?

WBC casts with bacteriuria
3+ proteinuria with fatty casts and oval fat bodies (Correct answer)
Waxy casts with granular casts only
RBC casts with hematuria

Correct answer: 3+ proteinuria with fatty casts and oval fat bodies

Nephrotic syndrome is characterized by massive proteinuria, hypoalbuminemia, and lipiduria, producing fatty casts and oval fat bodies (Maltese cross pattern) on urinalysis.

Question 66: A neonate with hyperbilirubinemia has a total bilirubin of 22 mg/dL at 72 hours of life. The MOST appropriate laboratory-guided intervention is:

Perform exchange transfusion immediately
Initiate phototherapy and obtain DAT and blood type (Correct answer)
Increase oral feeding frequency only
Repeat bilirubin in 24 hours without intervention

Correct answer: Initiate phototherapy and obtain DAT and blood type

Total bilirubin at this level in a 3-day-old neonate meets phototherapy threshold; DAT and blood typing identify hemolytic causes requiring escalated management.

Question 67: Which of the following is the MOST reliable method for identifying a patient prior to specimen collection in an inpatient setting?

Compare wristband information with the requisition using two identifiers (Correct answer)
Check the name on the door or whiteboard
Ask the patient to state their name and room number
Confirm identity with the nursing staff

Correct answer: Compare wristband information with the requisition using two identifiers

Two-identifier verification using the patient wristband compared to the requisition is the standard for positive patient identification.

Question 68: A laboratory technician develops respiratory distress after exposure to formaldehyde fumes. What is the most immediate intervention?

Administer 100% oxygen via non-rebreather mask
Have the person rinse their mouth with water for 5 minutes
Administer an inhaled bronchodilator from the first aid kit
Move the person to fresh air and assess airway, breathing, and circulation (Correct answer)

Correct answer: Move the person to fresh air and assess airway, breathing, and circulation

Removing the person from the exposure source and assessing ABCs is the immediate priority before any further treatment.

Question 69: Which documentation is MOST critical to include when reporting a critical (panic) value?

The patient's insurance information and attending physician's name
The time the result was reviewed by a supervisor
The name of the person notified, time of notification, and value reported (Correct answer)
The instrument ID and reagent lot number used for the test

Correct answer: The name of the person notified, time of notification, and value reported

Critical value documentation must include who was notified, the time of notification, and the value reported to ensure a complete audit trail.

Question 70: During a flooding emergency in the laboratory basement where specimens are processed, the FIRST priority for the MLS on duty is:

Documenting specimen status for continuity of care purposes
Personal safety and evacuation of all personnel (Correct answer)
Preserving critical reagent inventories by relocating them to upper floors
Contacting IT to protect laboratory information system servers

Correct answer: Personal safety and evacuation of all personnel

Personal safety and evacuation of personnel is always the first priority in any emergency before addressing equipment, specimens, or data.

Question 71: A specimen labeled with only the patient's last name and room number is received in the lab. Per CAP standards, this specimen should be:

Rejected unless it is a stat specimen
Processed with a notation of the deficiency
Rejected and a recollection requested with proper labeling (Correct answer)
Forwarded to the charge technologist for a decision

Correct answer: Rejected and a recollection requested with proper labeling

CAP standards require a minimum of two patient identifiers on every specimen label; a specimen with only one identifier must be rejected.

Question 72: Which biosafety level (BSL) is required when working with agents that pose a HIGH risk of life-threatening disease transmitted via aerosol for which no vaccine or therapy exists?

BSL-2
BSL-4 (Correct answer)
BSL-1
BSL-3

Correct answer: BSL-4

BSL-4 facilities handle the most dangerous agents with no available countermeasures, requiring full pressure suits or cabinet lines.

Question 73: Which component of patient documentation is most important when an MLS performs a corrected report after releasing erroneous results?

Verbally notifying only the ordering physician without written documentation
Deleting the original report from the electronic system
Issuing a corrected report that references the original incorrect report with the reason for correction (Correct answer)
Rerunning the specimen on a different analyzer without notation

Correct answer: Issuing a corrected report that references the original incorrect report with the reason for correction

A corrected report must reference the original incorrect report, state the reason for correction, and be clearly labeled as corrected to maintain a complete and transparent audit trail.

Question 74: Which conflict resolution approach is most effective in Medical Laboratory Scientist practice?

Collaborative problem-solving with all parties (Correct answer)
Avoiding the conflict entirely
Forcing one party to concede
Pretending the conflict does not exist

Correct answer: Collaborative problem-solving with all parties

Collaborative problem-solving involves all parties working together to find a mutually beneficial solution.

Question 75: The Six Sigma concept of 'defects per million opportunities' (DPMO) in laboratory medicine equates defects to:

Reagent lot failures per million specimens
Instrument downtime per million test runs
Patient results outside total allowable error per million tests (Correct answer)
Failed QC runs per million QC tests

Correct answer: Patient results outside total allowable error per million tests

In laboratory Six Sigma, a defect is any patient result that falls outside the total allowable error limit, and DPMO counts how often this occurs per million tests.

Question 76: Which of the following is an example of a pre-analytical error affecting laboratory results?

Hemolysis due to traumatic venipuncture (Correct answer)
Reagent deterioration during the assay
Software rounding errors in result reporting
Incorrect calibration of the analyzer

Correct answer: Hemolysis due to traumatic venipuncture

Hemolysis from traumatic venipuncture is a pre-analytical error occurring before the sample reaches the analyzer, potentially falsely elevating potassium and LDH.

Question 77: A chemical spill of sulfuric acid occurs in the chemistry lab. The FIRST action the MLS should take is:

Don appropriate PPE before approaching the spill (Correct answer)
Call the facility safety officer before doing anything
Neutralize the spill with sodium bicarbonate
Evacuate the entire building

Correct answer: Don appropriate PPE before approaching the spill

Personal protective equipment must be donned before approaching any chemical spill to protect the MLS from exposure.

Question 78: A patient refuses to provide a blood specimen. What is the FIRST action the MLS should take?

Call security to assist with the collection
Attempt to collect the specimen while the patient is distracted
Document the refusal and notify the nursing staff or ordering provider (Correct answer)
Cancel all laboratory orders for that patient

Correct answer: Document the refusal and notify the nursing staff or ordering provider

Competent adult patients have the right to refuse procedures; the refusal must be documented and the clinical team notified so patient care decisions can be made.

Question 79: Which action is REQUIRED when a laboratory's QC fails and patient results have already been reported?

Immediately cancel all pending orders
Rerun QC until it passes and document the passing result only
Inform only the billing department
Investigate the failure, notify the medical director, and consider recalling affected results (Correct answer)

Correct answer: Investigate the failure, notify the medical director, and consider recalling affected results

A retrospective QC failure requires root cause investigation, medical director notification, and assessment of whether reported patient results were clinically impacted.

Question 80: What is the primary purpose of performing a Polymerase Chain Reaction (PCR) test?

To amplify DNA for detection of pathogens (Correct answer)
To assess kidney function
To measure blood glucose levels
To identify blood clotting disorders

Correct answer: To amplify DNA for detection of pathogens

Polymerase Chain Reaction (PCR) is a powerful molecular biology technique used to amplify specific segments of DNA exponentially. This amplification allows for the detection of even minute amounts of genetic material from pathogens like viruses or bacteria, making it invaluable for diagnosing infectious diseases, identifying genetic disorders, and forensic analysis. PCR creates millions of copies of a target DNA sequence, enabling its detection and study.

Question 81: A random urine albumin-to-creatinine ratio (ACR) of 45 mg/g in a diabetic patient indicates:

Severe CKD stage 5
Nephrotic-range proteinuria
Normal renal function
Moderately increased albuminuria (microalbuminuria) (Correct answer)

Correct answer: Moderately increased albuminuria (microalbuminuria)

An ACR of 30–300 mg/g is classified as moderately increased albuminuria (formerly microalbuminuria) and is an early marker of diabetic nephropathy.

Question 82: A pregnant patient at 28 weeks gestation is scheduled for a 1-hour glucose challenge test (GCT). She states she ate breakfast 30 minutes ago. The MLS should:

Reschedule the test for another day when she can fast properly
Proceed with the test, as the GCT does not require fasting (Correct answer)
Perform a fasting glucose first, then administer the glucose load
Decline to perform the test until an order modification is received

Correct answer: Proceed with the test, as the GCT does not require fasting

The 1-hour glucose challenge test (GCT) is a non-fasting screening test; the patient does not need to fast before the 50-gram glucose load.

Question 83: How does collaboration enhance Clinical Procedures & Protocols in Medical Laboratory Scientist?

It brings diverse perspectives and improves outcomes (Correct answer)
It reduces individual accountability
It creates unnecessary meetings
It slows down the process

Correct answer: It brings diverse perspectives and improves outcomes

Collaboration brings together different viewpoints and expertise, leading to better decision-making and outcomes.

Question 84: What is the role of documentation in Emergency Procedures & Response for Medical Laboratory Scientist?

It is only for management review
It is unnecessary paperwork
It provides an accurate record for accountability and reference (Correct answer)
It should only be done monthly

Correct answer: It provides an accurate record for accountability and reference

Proper documentation in Emergency Procedures & Response ensures accountability, traceability, and serves as a reference for future decisions.

Question 85: The ethical principle of 'nonmaleficence' in laboratory practice means the MLS must:

Respect the patient's right to refuse testing
Ensure equitable access to laboratory services for all patients
Avoid actions that cause unnecessary harm to patients (Correct answer)
Act in the patient's best interest at all times

Correct answer: Avoid actions that cause unnecessary harm to patients

Nonmaleficence means 'do no harm' — the MLS must avoid practices that could injure or negatively impact patients.

Question 86: A method comparison study yields a slope of 1.12 and a y-intercept of 0.5. What type of error does the slope indicate?

Constant systematic error
Proportional systematic error (Correct answer)
Random error
Gross error

Correct answer: Proportional systematic error

A slope significantly different from 1.0 indicates proportional systematic error, where the new method reads proportionally higher or lower than the reference.

Question 87: A laboratory scientist is working with a patient specimen that may contain Coccidioides immitis. Which containment practice is MOST critical?

Perform all manipulations in a Class II BSC to prevent aerosol exposure (Correct answer)
Seal the specimen tube and process in a centrifuge only
Use a standard chemical fume hood with HEPA filtration
Process the specimen at an open bench with a face shield

Correct answer: Perform all manipulations in a Class II BSC to prevent aerosol exposure

Coccidioides immitis is a BSL-3 fungal pathogen; all manipulations must be performed in a Class II BSC to contain highly infectious airborne arthroconidia.

Question 88: In a mass casualty event affecting the hospital, the laboratory receives a surge of STAT orders. What process helps the lab prioritize testing during a disaster?

Shutting down non-critical analyzers to focus resources on hematology only
Contacting each ordering physician individually to negotiate turnaround times
Implementation of a crisis standards of care plan with tiered testing protocols (Correct answer)
First-in, first-out processing of all specimens equally

Correct answer: Implementation of a crisis standards of care plan with tiered testing protocols

Crisis standards of care plans establish tiered testing priorities (life-saving vs. non-urgent) to allocate limited laboratory resources effectively during mass casualty events.

Question 89: An MLS observes that a pediatric patient's wristband is loose and has slipped off onto the crib rail. What should happen before specimen collection?

Ask a parent or guardian to verbally confirm the child's name and date of birth
Replace or reattach the wristband with nursing staff verification before collection (Correct answer)
Proceed with collection using the crib card as the sole identifier
Collect the specimen and tape the wristband to the outside of the collection tube

Correct answer: Replace or reattach the wristband with nursing staff verification before collection

The wristband must be properly placed on the patient and verified with nursing staff before proceeding to maintain a reliable two-identifier check.

Question 90: A laboratory receives a specimen labeled only with a room number and no patient identifiers. The appropriate action is:

Reject the specimen and notify the clinical area to recollect (Correct answer)
Accept with a verbal patient name from the nursing station
Test the specimen and hold results pending identification
Process the specimen and add the identifier from the order

Correct answer: Reject the specimen and notify the clinical area to recollect

Two patient identifiers are required on every specimen; a label missing patient-specific identifiers renders the specimen unacceptable and it must be rejected to prevent patient identification errors.

Question 91: Which type of pipette is used for highly accurate liquid volume measurements?

Graduated cylinder
Pasteur pipette
Serological pipette
Micropipette (Correct answer)

Correct answer: Micropipette

Micropipettes are precision instruments designed for highly accurate and reproducible measurement and transfer of very small liquid volumes, typically in the microliter range. They are essential in molecular biology, clinical diagnostics, and other laboratory applications where exact volumes are critical for experimental integrity and reliable results. Their adjustable volume settings and disposable tips ensure precision and prevent cross-contamination.

Question 92: A QC result exceeds 3 standard deviations from the mean. According to Westgard rules, this triggers which rule?

1-3s (Correct answer)
R-4s
4-1s
2-2s

Correct answer: 1-3s

The 1-3s Westgard rule is a rejection rule triggered when a single control value exceeds ±3 SD from the mean, indicating probable error.

Question 93: Which scenario represents an example of a post-analytical documentation error?

Reporting results to the wrong patient's chart (Correct answer)
Failing to fast the patient before lipid testing
Using an expired collection tube
Mislabeling a tube at the bedside

Correct answer: Reporting results to the wrong patient's chart

Reporting results to the wrong patient's chart is a post-analytical error that occurs after testing is complete and can have serious clinical consequences.

Question 94: In urinalysis, a positive nitrite test indicates the presence of:

Gram-negative bacteria that reduce nitrate to nitrite (Correct answer)
Urinary tract inflammation regardless of infection
Gram-positive cocci such as Staphylococcus saprophyticus
High urinary protein concentration

Correct answer: Gram-negative bacteria that reduce nitrate to nitrite

The nitrite test detects bacteria (primarily Gram-negatives like E. coli) that convert dietary nitrate to nitrite via reductase enzymes; many Gram-positives lack this enzyme and produce a negative nitrite result.

Question 95: When assessing a patient for a glucose tolerance test (GTT), which pre-test instruction is MOST important to verify?

That the patient consumed a high-carbohydrate meal the night before
That the patient took insulin within 2 hours of the test
That the patient avoided caffeine for 24 hours
That the patient fasted for 8–12 hours and avoided strenuous exercise (Correct answer)

Correct answer: That the patient fasted for 8–12 hours and avoided strenuous exercise

An 8–12 hour fast and avoidance of strenuous exercise are essential preconditions for a valid GTT, as both can significantly alter glucose metabolism.

Question 96: When performing a Gram stain, which step differentiates gram-positive from gram-negative organisms?

Safranin counterstain
Decolorization with alcohol/acetone (Correct answer)
Gram's iodine (mordant) step
Crystal violet application

Correct answer: Decolorization with alcohol/acetone

Decolorization with alcohol or acetone removes crystal violet-iodine complexes from gram-negative cells (thin peptidoglycan) but not from gram-positive cells (thick peptidoglycan).

Question 97: An MLS suspects a colleague is diverting controlled substances from the laboratory. The most appropriate first step is to:

Confront the colleague directly and give them a chance to explain
Monitor the colleague for several months to gather more evidence
Ignore the situation unless it directly affects patient results
Report the suspicion to the supervisor or compliance officer immediately (Correct answer)

Correct answer: Report the suspicion to the supervisor or compliance officer immediately

Suspected diversion of controlled substances is a serious safety and legal issue that must be reported promptly through appropriate channels.

Question 98: A stool culture grows Salmonella typhi. Besides the clinical team, this result must be reported to:

The infection control committee within 30 days
Public health authorities, as it is a reportable pathogen (Correct answer)
The blood bank only
The pharmacy department

Correct answer: Public health authorities, as it is a reportable pathogen

Salmonella typhi (typhoid fever) is a nationally notifiable disease in the US; laboratories are required to report positive cultures to local and state public health departments.

Question 99: A critical value for serum potassium is reported to the nurse. The nurse is unavailable. What is the correct next step?

Wait 30 minutes and call again
Leave a voicemail and document the attempt
Contact the charge nurse or covering physician and document (Correct answer)
File the result and let the physician see it on rounds

Correct answer: Contact the charge nurse or covering physician and document

Critical values must be communicated to a responsible caregiver immediately; if the primary nurse is unavailable, the charge nurse or covering provider must be notified and all attempts documented.

Question 100: A prothrombin time (PT) is reported as an INR of 3.8 for a patient on warfarin therapy. The therapeutic range for most indications is 2.0–3.0. This result should be:

Reported as a critical value requiring immediate physician notification (Correct answer)
Reported only if the aPTT is also prolonged
Repeated before reporting due to suspected error
Reported routinely with next-day physician review

Correct answer: Reported as a critical value requiring immediate physician notification

An INR of 3.8 exceeds the typical upper critical threshold (often ≥4.0 or institution-specific), and supratherapeutic anticoagulation poses bleeding risk requiring prompt clinical notification.

Medical Laboratory Scientist (MLS) Examination — ASCP Board of Certification

The MLS(ASCP) certification exam validates competency across all major clinical laboratory disciplines including blood banking, chemistry, hematology, microbiology, immunology, urinalysis, and laboratory operations. It is administered as a 100-question Computer Adaptive Test (CAT) by the ASCP Board of Certification.

100

Questions

150 min

Time Limit

70%

To Pass

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