Prometric Exam Questions for Medical Lab Technologists 2026: 15 Practice MCQs with Answers and Rationale

The medical laboratory Prometric paper tests the bench knowledge a technologist or technician needs to produce a result a doctor can trust: specimen handling, clinical chemistry, haematology, microbiology, blood banking, quality control and safety. Most Gulf authorities set 100 to 150 single-best-answer MCQs over 2 to 3 hours, with a pass mark of about 60%.

The fifteen questions below are written to that blueprint. Allow about 70 seconds each, then read the rationale even when you were right. The exam keeps returning to pre-analytical errors, tube choice, interpretation of common patterns and quality-control rules.

For the syllabus by title, see the Prometric exam for lab technologists and technicians. If you are a scientist or specialist in one discipline, read the clinical biochemistry, microbiology and haematology guide.

Specimen collection and clinical chemistry

Question 1

Which tube is preferred for a plasma glucose sample that cannot be analysed for several hours?

1. Plain serum tube (red top)
2. Sodium fluoride/potassium oxalate tube (grey top)
3. EDTA tube (lavender top)
4. Sodium citrate tube (light blue top)

Answer: B. Red cells keep using glucose after collection, lowering the result by roughly 5–7% an hour at room temperature. Sodium fluoride inhibits glycolysis, which is why the grey-top tube is used for glucose and lactate.

Question 2

A haemolysed sample will most likely give a falsely high result for:

1. Sodium
2. Potassium
3. Albumin
4. Glucose

Answer: B. Red cells contain far more potassium than plasma, so haemolysis releases it into the sample. LDH, AST, phosphate and magnesium also rise. A haemolysed potassium should be reported with a comment or recollected, never released as it is.

Question 3

HbA1c reflects a patient's average blood glucose over approximately:

1. The last 24 hours
2. The last 2 weeks
3. The last 2–3 months
4. The last 12 months

Answer: C. HbA1c forms throughout the 120-day lifespan of the red cell, with recent weeks weighted most. Conditions that shorten red-cell survival, such as haemolysis or recent blood loss, give falsely low values.

Question 4

According to the Beer–Lambert law, absorbance is directly proportional to:

1. Concentration and path length
2. Wavelength only
3. Temperature and pH
4. Transmittance

Answer: A. Absorbance equals molar absorptivity multiplied by path length and concentration. Absorbance and transmittance are inversely and logarithmically related, which is why photometers report absorbance for calculation.

Haematology and coagulation

Question 5

Which anticoagulant is used for a complete blood count?

1. Sodium citrate
2. Lithium heparin
3. K2 or K3 EDTA
4. Sodium fluoride

Answer: C. EDTA chelates calcium and preserves cell morphology, making it the standard for the CBC and blood film. Citrate is used for coagulation tests, and heparin for many chemistry tests.

Question 6

A CBC shows a low MCV, low MCH, raised RDW and a low serum ferritin. The most likely diagnosis is:

1. Vitamin B12 deficiency
2. Iron deficiency anaemia
3. Beta thalassaemia trait
4. Anaemia of chronic disease

Answer: B. Microcytic, hypochromic red cells with a high RDW and low ferritin are typical of iron deficiency. Thalassaemia trait is also microcytic but usually has a normal RDW, normal ferritin and a relatively high red-cell count. B12 deficiency is macrocytic.

Question 7

Which test is used to monitor warfarin therapy?

1. Activated partial thromboplastin time (aPTT)
2. Prothrombin time reported as INR
3. Platelet count
4. Bleeding time

Answer: B. Warfarin lowers the vitamin K-dependent factors II, VII, IX and X, and the PT is most sensitive to factor VII. The INR standardises the PT between laboratories. Unfractionated heparin is monitored with the aPTT or anti-Xa.

Question 8

Following the recommended order of draw, which tube is collected immediately after blood culture bottles?

1. EDTA (lavender)
2. Sodium citrate (light blue)
3. Sodium fluoride (grey)
4. Lithium heparin (green)

Answer: B. The usual order is blood cultures, citrate, serum (with or without gel), heparin, EDTA, then fluoride. Drawing EDTA before other tubes can carry over potassium EDTA and falsely raise potassium and lower calcium.

Microbiology

Question 9

Gram-positive cocci in clusters are catalase positive and coagulase positive. The organism is most likely:

1. Streptococcus pyogenes
2. Staphylococcus epidermidis
3. Staphylococcus aureus
4. Enterococcus faecalis

Answer: C. Catalase separates staphylococci (positive) from streptococci and enterococci (negative). Coagulase then separates Staphylococcus aureus (positive) from coagulase-negative species such as S. epidermidis.

Question 10

Which stain is used to detect Mycobacterium tuberculosis in a sputum smear?

1. Gram stain
2. Ziehl–Neelsen stain
3. India ink
4. Giemsa stain

Answer: B. Mycobacteria have mycolic acid in their cell walls and resist decolourisation by acid-alcohol, so they appear red on Ziehl–Neelsen staining. Auramine fluorescent staining is a more sensitive screening alternative. India ink is used for Cryptococcus.

Question 11

The standard autoclave cycle for sterilising laboratory media and waste is:

1. 100 °C for 5 minutes
2. 121 °C at about 15 psi for 15–20 minutes
3. 160 °C dry heat for 10 minutes
4. 70 °C for 30 minutes

Answer: B. Saturated steam at 121 °C and about 15 psi for at least 15 minutes kills bacterial spores. Larger loads need longer cycles, and each run is checked with chemical indicators, with biological indicators at set intervals.

Blood bank

Question 12

In an emergency when the patient's blood group is unknown, which red cells are issued?

1. AB positive
2. O negative
3. A negative
4. B positive

Answer: B. Group O red cells carry no A or B antigens, and RhD-negative cells avoid sensitising a woman of child-bearing age. For plasma the logic is reversed: group AB plasma has no anti-A or anti-B and is the universal plasma.

Question 13

A major crossmatch tests:

1. Donor plasma against recipient red cells
2. Recipient serum or plasma against donor red cells
3. Donor red cells against donor plasma
4. Recipient red cells against anti-D only

Answer: B. The major crossmatch looks for antibodies in the recipient that would destroy the donor's red cells, which is the cause of an acute haemolytic transfusion reaction. It follows ABO and RhD grouping and an antibody screen.

Quality control and laboratory safety

Question 14

Under Westgard rules, what does a 1-3s violation mean?

1. One control result is outside ±3 standard deviations, so the run is rejected
2. Three consecutive controls are within ±1 standard deviation
3. The run is accepted with a warning
4. The calibration is due in three days

Answer: A. A single control beyond ±3 SD indicates a random error large enough to reject the run, investigate, correct and rerun patient samples. A 1-2s result is a warning rule that triggers checking against the other rules.

Question 15

What is the correct way to deal with a small blood spill on the bench?

1. Wipe it with a dry tissue and continue working
2. Wear gloves, cover with absorbent material, apply a freshly prepared hypochlorite solution, leave for the contact time, then clean
3. Spray with 70% alcohol and leave it to dry
4. Wash it into the sink with water

Answer: B. Blood is treated as potentially infectious. A freshly prepared sodium hypochlorite solution, commonly a 1:10 dilution of household bleach for blood, inactivates blood-borne viruses after the required contact time. Waste goes into the correct clinical waste stream and the incident is reported.

How to use these questions

• Find your weak discipline. Lab exams cover four or five sciences, and most candidates are strong in the one they work in daily. The others decide whether you pass.
• Revise the pre-analytical stage. Tube choice, order of draw, haemolysis, storage and transport appear in every paper.
• Practise under time. Use the Medical Laboratory Technologist bank, or the Medical Laboratory Technician bank if you hold a diploma.
• Use a structured plan. The 30-day study plan adapts well to lab disciplines, and best books and resources lists standard references.

Licensing details are in the DHA licence for lab technologists, and on the SCFHS, QCHP and DOH lab exam pages. Pay by country is in lab technologist salary. When you are ready, join the lab talent pool.

Frequently asked questions

How many questions are in the Prometric lab technologist exam?

Usually 100 to 150 MCQs over 2 to 3 hours. Your eligibility notice gives the exact number for your authority and title.

What is the pass mark for the lab technologist exam?

About 60% for most Gulf authorities, sometimes reported as a scaled score.

Is the technician exam easier than the technologist exam?

It covers the same disciplines at a more practical, procedural level, with fewer interpretation questions. The pass rules are similar.

Which subjects come up most?

Clinical chemistry and haematology usually carry the most marks, followed by microbiology and blood bank. Quality control, safety and specimen handling run across all of them.

Are these questions from the real exam?

No. They are original practice questions written to the published blueprint. Real exam content is confidential.