بنك أسئلة المختبرات الطبية الهيئة السعودية (SQB) | أسئلة البرومترك الشاملة مع الشرح

Q21: A patient’s serum reacts with all screening cells at the antihuman globulin phase, and the autocontrol is positive. What is the most likely explanation?

• [A] Alloantibody to a high-frequency antigen
• [B] Cold autoantibody
• [C] Warm autoantibody ✔ (Correct Answer)
• [D] ABO incompatibility

💡 Explanation:
Panreactivity at AHG with a positive autocontrol suggests a warm autoantibody, especially when reactivity occurs at 37°C/AHG.

Why other options are wrong:
• A — An antibody to a high-frequency antigen often has a negative autocontrol.
• B — Cold autoantibodies commonly react at lower temperatures.
• D — ABO incompatibility does not cause this antibody-screen pattern.

📌 Exam Pearl: Adsorption studies may be required to identify underlying alloantibodies in patients with warm autoantibodies.

Q22: Which urinalysis finding is most characteristic of nephrotic syndrome?

• [A] Large numbers of dysmorphic RBCs
• [B] Oval fat bodies ✔ (Correct Answer)
• [C] WBC casts
• [D] Hexagonal crystals

💡 Explanation:
Oval fat bodies are renal tubular epithelial cells containing lipid droplets and are typical of nephrotic syndrome.

Why other options are wrong:
• A — Dysmorphic RBCs suggest glomerular bleeding.
• C — WBC casts suggest pyelonephritis or interstitial nephritis.
• D — Hexagonal crystals suggest cystinuria.

📌 Exam Pearl: Fatty casts and oval fat bodies create a “Maltese cross” under polarized light.

Q23: A serum glucose result is 3.1 mmol/L in a patient whose sample remained unseparated at room temperature for 6 hours. What is the most likely pre-analytical cause?

• [A] Glycolysis by blood cells ✔ (Correct Answer)
• [B] Lipemia interference
• [C] Increased bilirubin production
• [D] Contamination with EDTA

💡 Explanation:
Unseparated blood cells metabolize glucose through glycolysis, causing falsely low glucose concentration.

Why other options are wrong:
• B — Lipemia affects photometric assays but does not explain delayed glucose loss.
• C — Bilirubin does not cause this pattern.
• D — EDTA contamination more often causes high potassium and low calcium.

📌 Exam Pearl: Separate serum/plasma promptly or use glycolysis-inhibiting collection methods when delay is expected.

Q24: Which RBC index is calculated as: $\text{MCV} = \frac{\text{Hematocrit} \times 10}{\text{RBC count}}$?

• [A] MCH
• [B] MCHC
• [C] MCV ✔ (Correct Answer)
• [D] RDW

💡 Explanation:
The stated formula calculates mean corpuscular volume (MCV).

Why other options are wrong:
• A — MCH is hemoglobin divided by RBC count.
• B — MCHC is hemoglobin divided by hematocrit.
• D — RDW measures RBC size variability.

📌 Exam Pearl: MCV is expressed in femtoliters (fL) and classifies anemia as microcytic, normocytic, or macrocytic.

Q25: A sputum Gram stain shows many neutrophils, few squamous epithelial cells, and numerous lancet-shaped Gram-positive diplococci. Which organism is most likely?

• [A] Streptococcus pneumoniae ✔ (Correct Answer)
• [B] Staphylococcus epidermidis
• [C] Neisseria meningitidis
• [D] Haemophilus influenzae

💡 Explanation:
Lancet-shaped Gram-positive diplococci in a high-quality sputum specimen are typical of Streptococcus pneumoniae.

Why other options are wrong:
• B — S. epidermidis forms clusters and is often skin flora.
• C — N. meningitidis is Gram-negative diplococci.
• D — H. influenzae is a small pleomorphic Gram-negative coccobacillus.

📌 Exam Pearl: Few squamous epithelial cells indicate a lower-respiratory specimen with minimal oral contamination.

Q26: A patient has a positive hepatitis B surface antigen (HBsAg) and positive hepatitis B core IgM antibody (anti-HBc IgM). Which interpretation is most appropriate?

• [A] Immunity due to vaccination
• [B] Acute hepatitis B infection ✔ (Correct Answer)
• [C] Resolved hepatitis B infection
• [D] Chronic infection with immunity

💡 Explanation:
HBsAg with anti-HBc IgM indicates acute hepatitis B infection.

Why other options are wrong:
• A — Vaccination causes anti-HBs alone.
• C — Resolved infection usually has anti-HBs and total anti-HBc but lacks HBsAg.
• D — Chronic infection typically lacks anti-HBc IgM.

📌 Exam Pearl: Anti-HBc IgM is a primary marker of recent/acute HBV infection.

Q27: Which stain is routinely used to demonstrate acid-fast bacilli in a sputum specimen?

• [A] Gram stain
• [B] India ink stain
• [C] Ziehl-Neelsen stain ✔ (Correct Answer)
• [D] Wright stain

💡 Explanation:
Ziehl-Neelsen stain detects acid-fast bacilli due to mycolic acids present in the cell wall.

Why other options are wrong:
• A — Gram stain poorly stains mycobacteria.
• B — India ink demonstrates Cryptococcus capsule.
• D — Wright stain is used for blood cells and blood parasites.

📌 Exam Pearl: Acid-fast smear positivity does not distinguish M. tuberculosis complex from nontuberculous mycobacteria.

Q28: During a blood transfusion, a patient develops fever, flank pain, hypotension, and hemoglobinuria. What is the first laboratory/clinical action?

• [A] Continue the transfusion at a slower rate
• [B] Stop the transfusion and initiate transfusion-reaction investigation ✔ (Correct Answer)
• [C] Administer an antihistamine and resume transfusion
• [D] Issue another unit from the same donor

💡 Explanation:
Symptoms of acute hemolytic reaction require immediate transfusion cessation and formal investigation.

Why other options are wrong:
• A — Slowing the transfusion is unsafe.
• C — Antihistamines do not treat suspected hemolysis.
• D — Another unit from the same donor is inappropriate before investigation.

📌 Exam Pearl: Maintain IV access with appropriate normal saline and notify the clinical team and blood bank immediately.

Q29: Which analyte is most useful for assessing short-term glycemic control over approximately 2–3 weeks?

• [A] Hemoglobin A1c
• [B] Fructosamine ✔ (Correct Answer)
• [C] C-peptide
• [D] Fasting insulin

💡 Explanation:
Fructosamine reflects glycation of serum proteins and approximates glycemic control over the previous 2–3 weeks.

Why other options are wrong:
• A — HbA1c reflects approximately 2–3 months.
• C — C-peptide reflects endogenous insulin secretion.
• D — Fasting insulin does not assess average glycemia.

📌 Exam Pearl: Fructosamine is useful when HbA1c is unreliable because of altered RBC survival (e.g., hemolytic anemia).

Q30: A tissue section shows weak nuclear staining with hematoxylin. Which corrective action is most appropriate?

• [A] Increase bluing time
• [B] Shorten dehydration time
• [C] Increase hematoxylin staining time ✔ (Correct Answer)
• [D] Replace xylene with alcohol

💡 Explanation:
Weak hematoxylin staining is corrected by increasing hematoxylin staining time or ensuring reagent freshness and concentration.

Why other options are wrong:
• A — Bluing changes the color shift, not initial weak nuclear uptake.
• B — Dehydration occurs later in the staining process.
• D — Xylene is unrelated to nuclear staining intensity.

📌 Exam Pearl: Hematoxylin stains nucleic acids (nuclei); eosin stains cytoplasm and extracellular matrix.

Q31: A peripheral smear shows macro-ovalocytes and hypersegmented neutrophils. Which deficiency is most likely?

• [A] Iron deficiency
• [B] Vitamin B12 or folate deficiency ✔ (Correct Answer)
• [C] Glucose-6-phosphate dehydrogenase deficiency
• [D] Thalassemia trait

💡 Explanation:
Macro-ovalocytes and hypersegmented neutrophils are classic hallmarks of megaloblastic anemia caused by Vitamin B12 or folate deficiency.

Why other options are wrong:
• A — Iron deficiency produces microcytic hypochromic RBCs.
• C — G6PD deficiency produces bite cells and Heinz bodies.
• D — Thalassemia trait produces target cells and microcytosis.

📌 Exam Pearl: Evaluate vitamin B12 and folate levels promptly because B12 deficiency can cause irreversible neurological complications.

Q32: Which organism is most commonly associated with pseudomembranous colitis after antibiotic therapy?

• [A] Clostridioides difficile ✔ (Correct Answer)
• [B] Campylobacter jejuni
• [C] Salmonella enterica
• [D] Shigella sonnei

💡 Explanation:
C. difficile produces enterotoxin (Toxin A) and cytotoxin (Toxin B) that cause antibiotic-associated pseudomembranous colitis.

Why other options are wrong:
• B — Campylobacter causes inflammatory diarrhea without classic pseudomembranes.
• C — Salmonella causes acute gastroenteritis.
• D — Shigella causes bacillary dysentery.

📌 Exam Pearl: Test unformed (liquid/soft) stool samples from symptomatic patients for toxin detection.

Q33: A laboratory receives a specimen labeled with two different patient identifiers that do not match the request form. What is the most appropriate action?

• [A] Correct the label using the request form
• [B] Process the specimen if the test is urgent
• [C] Reject the specimen and request recollection ✔ (Correct Answer)
• [D] Ask the ward clerk which identifier is correct

💡 Explanation:
Mismatched identifiers create an unacceptable risk of wrong-patient error. Rejection and recollection are mandatory.

Why other options are wrong:
• A — Staff must never relabel primary specimens retrospectively.
• B — Clinical urgency does not override patient safety identification protocols.
• D — Verbal confirmations are insufficient for resolving mismatched labeling errors.

📌 Exam Pearl: Proper patient identification is a primary quality control barrier in pre-analytical testing.

Q34: A newborn has a positive DAT and elevated unconjugated bilirubin. The mother is group O, and the infant is group A. Which condition is most likely?

• [A] ABO hemolytic disease of the fetus and newborn ✔ (Correct Answer)
• [B] Hemophilia A
• [C] Hereditary spherocytosis
• [D] Vitamin K deficiency

💡 Explanation:
Group O mothers naturally possess IgG anti-A,B antibodies that cross the placenta and target group A or B fetal RBCs, leading to ABO HDFN.

Why other options are wrong:
• B — Hemophilia A causes bleeding disorders, not positive DAT or immune hemolysis.
• C — Hereditary spherocytosis is a membrane defect, independent of maternal blood group.
• D — Vitamin K deficiency causes hemorrhagic disease of the newborn.

📌 Exam Pearl: ABO HDFN is often milder than Rh-mediated disease but frequently presents in first pregnancies.

Q35: Which crystal is most often found in acidic urine?

• [A] Triple phosphate
• [B] Amorphous phosphate
• [C] Calcium phosphate
• [D] Uric acid ✔ (Correct Answer)

💡 Explanation:
Uric acid crystals precipitate predominantly in acidic urine ($\text{pH} < 5.7$).

Why other options are wrong:
• A — Triple phosphate crystals form in alkaline urine.
• B — Amorphous phosphates precipitate in alkaline urine.
• C — Calcium phosphate crystals are found in neutral to alkaline urine.

📌 Exam Pearl: Uric acid crystals show pleomorphism (yellow-brown rhombic, rosette, or diamond shapes) under light microscopy.

Q36: A patient has sodium 140 mmol/L, chloride 104 mmol/L, and bicarbonate 12 mmol/L. What is the calculated anion gap?

• [A] 12 mmol/L
• [B] 20 mmol/L
• [C] 24 mmol/L ✔ (Correct Calculated Result)
• [D] 36 mmol/L

💡 Explanation:
The formula for Anion Gap is: $\text{AG} = \text{Na}^+ - (\text{Cl}^- + \text{HCO}_3^-)$.
$\text{AG} = 140 - (104 + 12) = 140 - 116 = 24\text{ mmol/L}$.

📌 Exam Pearl: An elevated anion gap ($> 12\text{ mmol/L}$) indicates high anion gap metabolic acidosis (e.g., ketoacidosis, lactic acidosis).

Q37: Which coagulation factor deficiency usually prolongs the aPTT but not the PT?

• [A] Factor VII deficiency
• [B] Factor VIII deficiency ✔ (Correct Answer)
• [C] Factor V deficiency
• [D] Factor X deficiency

💡 Explanation:
Factor VIII belongs exclusively to the intrinsic pathway; its deficiency prolongs aPTT while PT remains normal.

Why other options are wrong:
• A — Factor VII is part of the extrinsic pathway and prolongs PT only.
• C — Factor V is part of the common pathway and prolongs both PT and aPTT.
• D — Factor X is part of the common pathway and prolongs both PT and aPTT.

📌 Exam Pearl: Hemophilia A is Factor VIII deficiency, whereas Hemophilia B is Factor IX deficiency.

Q38: A urine culture from a properly collected midstream sample grows more than 100,000 CFU/mL of a single lactose-fermenting Gram-negative rod. Which next step is most appropriate?

• [A] Report mixed urogenital flora
• [B] Perform identification and antimicrobial susceptibility testing ✔ (Correct Answer)
• [C] Reject the culture as contaminated
• [D] Incubate anaerobically for 48 hours

💡 Explanation:
Significant pure growth ($\ge 10^5\text{ CFU/mL}$) from a clean-catch midstream urine indicates a true UTI requiring species ID and AST.

Why other options are wrong:
• A — Mixed flora applies when multiple organisms grow in low counts.
• C — Pure growth of $\ge 10^5\text{ CFU/mL}$ represents pathogen growth, not contamination.
• D — Routine urine pathogens are aerobic or facultative anaerobes.

📌 Exam Pearl: Escherichia coli is the predominant lactose-fermenting Gram-negative rod in community-acquired UTIs.

Q39: Which histochemical stain is used to demonstrate iron in bone marrow aspirates?

• [A] Congo red
• [B] Prussian blue ✔ (Correct Answer)
• [C] Periodic acid-Schiff
• [D] Ziehl-Neelsen

💡 Explanation:
Prussian blue (Perls' stain) reacts with ferric iron to form insoluble ferric ferrocyanide, demonstrating storage iron.

Why other options are wrong:
• A — Congo red is specific for amyloid deposits.
• C — PAS stains glycogen, mucins, and fungal walls.
• D — Ziehl-Neelsen demonstrates acid-fast bacteria.

📌 Exam Pearl: Absence of stainable iron in bone marrow confirms iron deficiency anemia.

Q40: A blood bank technologist detects a clinically significant anti-K antibody in a recipient. Which RBC units should be selected?

• [A] K-positive, AHG crossmatch compatible
• [B] K-negative, crossmatch compatible ✔ (Correct Answer)
• [C] Group O RBCs regardless of K antigen status
• [D] Washed RBCs regardless of K antigen status

💡 Explanation:
Anti-K is a IgG, clinically significant antibody that causes severe hemolytic transfusion reactions. K-negative crossmatch-compatible units are required.

Why other options are wrong:
• A — Transfusing K-positive units causes acute/delayed hemolysis.
• C — ABO group selection does not protect against Kell antigen reactions.
• D — Washing removes donor plasma proteins, not RBC membrane antigens.

📌 Exam Pearl: Antigen-negative RBC selection is mandatory for clinically significant red cell alloantibodies.

"أسئلة امتحان الهيئة السعودية للتخصصات الطبية مختبرات طبية (2026) SCFHS Medical Laboratory Prometric Exam MCQs"

مرجع معتمد

بنك أسئلة المختبرات الطبية - الهيئة السعودية للتخصصات الصحية (SQB)

تجميعات وااختبارات تجريبية محاكية لنظام البرومترك مع الإجابات المشروحة

يُعد اجتياز اختبار الهيئة السعودية للتخصصات الصحية (SCFHS) لقسم Medical Laboratory الخطوة الأساسية للحصول على التصنيف والتصريح المهني للعمل داخل المملكة. يوفر لك هذا المرجع مجموعة محاكيه من الأسئلة والتمارين التقييمية لضمان الاستعداد الكامل للاختبار.

📝 نماذج الأسئلة المشروحة (SQB Model)

Q1: A 45-year-old male presents with fatigue. Blood test shows High Serum Iron, High Ferritin, and Decreased Total Iron-Binding Capacity (TIBC). Which of the following is the most likely diagnosis?

• [A] Iron Deficiency Anemia
• [B] Anemia of Chronic Disease
• [C] Hemochromatosis ✔ (Correct Answer)
• [D] Thalassemia Minor

💡 Explanation:
Elevated serum iron and ferritin levels accompanied by decreased TIBC strongly indicate Hemochromatosis (iron overload). In contrast, Iron Deficiency Anemia presents with low ferritin and elevated TIBC.

Q2: Which Culture Media is selectively used to isolate Pseudomonas aeruginosa from mixed samples?

• [A] Blood Agar
• [B] Cetrimide Agar ✔ (Correct Answer)
• [C] Chocolate Agar
• [D] MacConkey Agar

💡 Explanation:
Cetrimide Agar acts as a selective medium that inhibits the growth of most other bacteria while favoring the isolation of Pseudomonas aeruginosa and stimulating its pyocyanin pigment production.

تحميل بنك الأسئلة الكامل والتجميعات PDF

احصل على أكثر من 500 سؤال محاكي لاختبار الهيئة السعودية قسم المختبرات الطبية بصيغة PDF جاهزة للطباعة والمذاكرة.

تحميل الملفات مجاناً

أسئلة امتحان الهيئة السعودية للتخصصات الطبية مختبرات طبية 2026 SCFHS Medical Laboratory Prometric Exam MCQs"

 سأعود لنشر أحدث الاسئلة المتاحة لامتحان الهيئة السعودية للتخصصات الطبية مختبرات 2026 ولكن يجب الإشارة لاهم التعديلات علي الامتحانات وقواعدها: 

The current SCFHS SLLE applicant guide describes a 200-item, four-option, single-best-answer examination divided into two 100-question parts, with 120 minutes per part and a scheduled 30-minute break. It evaluates both knowledge and scenario-based interpretation, decision making, calculation, and laboratory-procedure competencies.

• Total questions: 200

• Format: Four options per question: A, B, C, D

• Instruction: Select the one best answer

• Part I: Questions 1–100; recommended time 120 minutes

• Break: 30 minutes

• Part II: Questions 101–200; recommended time 120 minutes

• Candidate-facing sections: Questions only; answers are provided separately after Question 200.

BLUEPRINT

The following practice blueprint follows the public SLLE domain ranges. SCFHS notes that actual blueprint distributions may vary within stated tolerances; this simulation uses a balanced 200-question allocation.

Domain	Target %	Practice count	Major topics represented
Blood Bank / Immunohematology	15–20%	34	ABO/Rh, antibody testing, transfusion, HDFN, reactions, components
Urinalysis & Other Body Fluids	5–10%	14	Urinalysis, sediment, CSF, synovial, serous fluid, semen, feces
Clinical Chemistry	15–20%	34	Acid-base, electrolytes, renal/liver testing, endocrinology, toxicology
Hematology & Hemostasis	15–20%	34	CBC, morphology, hemoglobinopathy, coagulation, flow cytometry
Immunology & Serology	5–10%	14	Autoimmunity, immune response, viral and infectious serology
Histo- & Cytotechniques	5–10%	12	Fixation, processing, staining, frozen sections, cytology
Microbiology	15–20%	34	Bacteriology, mycology, virology, parasitology, AST
Laboratory Operations	5–10%	12	QC, validation, safety, calculations, information systems
Patient Safety & Professionalism	5–10%	12	Identification, critical values, confidentiality, ethics, communication
Total	100%	200	—

 سأقوم بنشر 20 سؤال بشكل شبه يومي وبعد اكتمال 200 سؤال سأقوم بنش الإجابات مع  بشرح مبسط لكل سؤال وجوابه لتعم الفائدة ونغطي اكبر قدر ممكن من المعلومات بالتوفيق 

PART I

Questions 1–100
Recommended time: 120 minutes

1

A patient’s RBCs agglutinate with anti-A and anti-D reagents but not with anti-B reagent. The serum agglutinates B reagent cells but not A1 cells. What is the most likely ABO/Rh type?

A. A positive
B. A negative
C. AB positive
D. O positive

Correct answer: A

Why: Anti-A and anti-D reactivity identifies A-positive RBCs. Serum reaction with B cells confirms anti-B, which is expected in group A individuals.

Why the other options are wrong:
B — An A-negative person would not react with anti-D.
C — AB-positive serum should generally lack anti-A and anti-B.
D — Group O RBCs do not react with anti-A.

2

Which anticoagulant is most appropriate for routine complete blood count testing?

A. Sodium citrate
B. EDTA
C. Heparin
D. Sodium fluoride

Correct answer: B

Why: EDTA chelates calcium and preserves cellular morphology, making it appropriate for routine CBC testing.

Why the other options are wrong:
A — Sodium citrate is primarily used for coagulation testing.
C — Heparin is mainly used for plasma chemistry and blood gases.
D — Sodium fluoride inhibits glycolysis for glucose testing.

3

A fresh urine specimen is strongly positive for nitrite and leukocyte esterase. Which finding is most consistent with these results?

A. Bacterial urinary tract infection
B. Nephrotic syndrome
C. Diabetic ketoacidosis
D. Hepatocellular jaundice

Correct answer: A

Why: Nitrite suggests nitrate-reducing bacteria, and leukocyte esterase indicates neutrophils. Together they support bacterial UTI.

Why the other options are wrong:
B — Nephrotic syndrome is characterized by significant proteinuria and lipiduria.
C — Ketoacidosis produces ketones and often glucose.
D — Hepatocellular jaundice may cause bilirubinuria and increased urobilinogen.

4

Which enzyme is most specific for acute pancreatitis when measured in serum?

A. Alkaline phosphatase
B. Creatine kinase
C. Lipase
D. Lactate dehydrogenase

Correct answer: C

Why: Serum lipase is more pancreas-specific and usually remains elevated longer than amylase in acute pancreatitis.

Why the other options are wrong:
A — ALP is associated with cholestasis and bone disease.
B — CK reflects muscle injury.
D — LD is nonspecific.

5

A Gram-positive coccus produces catalase and coagulase. Which organism is most likely?

A. Staphylococcus aureus
B. Streptococcus pyogenes
C. Enterococcus faecalis
D. Streptococcus pneumoniae

Correct answer: A

Why: Staphylococcus aureus is Gram-positive, catalase-positive, and coagulase-positive.

Why the other options are wrong:
B — S. pyogenes is catalase-negative.
C — Enterococcus is catalase-negative.
D — S. pneumoniae is catalase-negative and alpha-hemolytic.

6

Which blood component is most appropriate for a patient with active bleeding and a critically low fibrinogen concentration?

A. Packed red blood cells
B. Platelet concentrate
C. Fresh frozen plasma
D. Cryoprecipitate

Correct answer: D

Why: Cryoprecipitate is concentrated in fibrinogen and is used when fibrinogen replacement is required.

Why the other options are wrong:
A — RBCs restore oxygen-carrying capacity.
B — Platelets treat thrombocytopenia or platelet dysfunction.
C — FFP provides multiple clotting factors but is less concentrated for fibrinogen replacement.

7

The presence of Auer rods in blasts is most strongly associated with:

A. Acute lymphoblastic leukemia
B. Acute myeloid leukemia
C. Chronic lymphocytic leukemia
D. Hairy cell leukemia

Correct answer: B

Why: Auer rods are azurophilic needle-like inclusions in myeloid blasts and strongly support AML.

Why the other options are wrong:
A — ALL blasts do not contain Auer rods.
C — CLL shows mature lymphocytosis and smudge cells.
D — Hairy cell leukemia shows lymphocytes with cytoplasmic projections.

8

A urine specific gravity of 1.035 is most likely caused by:

A. Marked dilute urine
B. Diabetes insipidus
C. Increased dissolved solutes
D. Inability to concentrate urine

Correct answer: C

Why: A high specific gravity reflects a high concentration of dissolved solutes, such as glucose, protein, radiographic contrast material, or marked dehydration.

Why the other options are wrong:
A — Dilute urine has low specific gravity.
B — Diabetes insipidus commonly produces low specific gravity.
D — Poor concentrating ability tends toward isosthenuria.

9

Which test is routinely used to monitor warfarin therapy?

A. Activated partial thromboplastin time
B. Prothrombin time expressed as INR
C. Thrombin time
D. Fibrinogen assay

Correct answer: B

Why: Warfarin affects vitamin K-dependent clotting factors and is monitored by PT standardized as INR.

Why the other options are wrong:
A — aPTT is commonly used for unfractionated heparin monitoring.
C — TT assesses conversion of fibrinogen to fibrin and is sensitive to heparin.
D — Fibrinogen alone does not monitor warfarin effect.

10

Which immunoglobulin class crosses the placenta most efficiently?

A. IgA
B. IgE
C. IgG
D. IgM

Correct answer: C

Why: IgG is actively transported across the placenta and provides passive fetal immunity.

Why the other options are wrong:
A — Secretory IgA is prominent in mucosal secretions and breast milk.
B — IgE mediates immediate hypersensitivity.
D — IgM is too large to cross the placenta efficiently.

11

A serum sample is visibly hemolyzed. Which analyte is most likely to be falsely increased?

A. Sodium
B. Potassium
C. Chloride
D. Calcium

Correct answer: B

Why: RBCs contain much higher potassium concentrations than plasma. Hemolysis releases intracellular potassium and can cause pseudohyperkalemia.

Why the other options are wrong:
A — Sodium is lower inside RBCs and is not typically falsely elevated by hemolysis.
C — Chloride is not the characteristic hemolysis-sensitive analyte.
D — Calcium is not commonly falsely increased from hemolysis.

12

Which organism is oxidase-positive and commonly produces blue-green pigment in culture?

A. Escherichia coli
B. Klebsiella pneumoniae
C. Pseudomonas aeruginosa
D. Acinetobacter baumannii

Correct answer: C

Why: Pseudomonas aeruginosa is oxidase-positive and may produce blue-green pyocyanin pigment.

Why the other options are wrong:
A — E. coli is oxidase-negative.
B — Klebsiella is oxidase-negative.
D — Acinetobacter is oxidase-negative.

13

The primary purpose of formalin fixation in histopathology is to:

A. Remove paraffin from tissue sections
B. Preserve tissue morphology and prevent autolysis
C. Stain cellular nuclei blue
D. Dehydrate tissue before embedding

Correct answer: B

Why: Formalin fixation cross-links proteins, limits autolysis and putrefaction, and preserves tissue architecture.

Why the other options are wrong:
A — Xylene removes paraffin during staining.
C — Hematoxylin stains nuclei.
D — Alcohols dehydrate tissue.

14

A direct antiglobulin test detects:

A. Free antibody in patient serum
B. Antibody or complement attached to patient RBCs in vivo
C. ABO antibodies in donor plasma
D. Platelet-associated antibodies only

Correct answer: B

Why: The DAT detects immunoglobulin and/or complement bound to RBCs in vivo.

Why the other options are wrong:
A — Indirect antiglobulin testing detects free serum antibody.
C — ABO antibodies are detected by reverse grouping.
D — DAT is not a platelet antibody test.

15

Which laboratory result most strongly supports iron deficiency anemia?

A. Increased ferritin
B. Increased transferrin saturation
C. Decreased total iron-binding capacity
D. Decreased ferritin

Correct answer: D

Why: Ferritin reflects iron stores and is typically reduced in iron deficiency anemia.

Why the other options are wrong:
A — Ferritin is usually low, not increased.
B — Transferrin saturation is reduced.
C — TIBC generally rises in uncomplicated iron deficiency.

16

A CSF specimen is cloudy with elevated neutrophils, high protein, and low glucose. Which condition is most likely?

A. Viral meningitis
B. Bacterial meningitis
C. Multiple sclerosis
D. Subarachnoid hemorrhage

Correct answer: B

Why: Neutrophilic pleocytosis, elevated protein, low glucose, and cloudy CSF support bacterial meningitis.

Why the other options are wrong:
A — Viral meningitis usually has lymphocytic predominance and normal glucose.
C — Multiple sclerosis may show oligoclonal bands.
D — Subarachnoid hemorrhage causes RBCs and xanthochromia.

17

Which quality-control rule is violated when one control result exceeds the mean by more than 3 standard deviations?

A. 1_2s
B. 1_3s
C. 2_2s
D. R_4s

Correct answer: B

Why: The 1_3s rule is violated when one QC result exceeds the mean by more than 3 SD; it is a rejection rule.

Why the other options are wrong:
A — 1_2s is generally a warning rule.
C — 2_2s requires two consecutive results beyond 2 SD on the same side.
D — R_4s requires a 4-SD difference between two controls in one run.

18

A patient has pH 7.28, pCO₂ 60 mmHg, and bicarbonate 27 mmol/L. What is the primary acid-base disorder?

A. Metabolic acidosis
B. Metabolic alkalosis
C. Respiratory acidosis
D. Respiratory alkalosis

Correct answer: C

Why: Low pH with elevated pCO₂ indicates respiratory acidosis. Bicarbonate is only slightly increased, consistent with limited acute compensation.

Why the other options are wrong:
A — Metabolic acidosis has reduced bicarbonate as the primary abnormality.
B — Metabolic alkalosis raises pH and bicarbonate.
D — Respiratory alkalosis lowers pCO₂ and raises pH.

19

Which culture medium is selective for Gram-negative enteric bacilli and differentiates lactose fermenters?

A. Blood agar
B. MacConkey agar
C. Chocolate agar
D. Sabouraud agar

Correct answer: B

Why: MacConkey agar inhibits many Gram-positive organisms and differentiates lactose-fermenting from non-lactose-fermenting Gram-negative bacilli.

Why the other options are wrong:
A — Blood agar is enriched and differential for hemolysis.
C — Chocolate agar supports fastidious organisms.
D — Sabouraud agar is used for fungi.

20

A platelet count is unexpectedly 28 × 10⁹/L, but the blood smear shows abundant platelet clumps. What is the most appropriate next step?

A. Report severe thrombocytopenia immediately
B. Repeat the count using a citrate-anticoagulated specimen
C. Perform a bone marrow examination
D. Add platelet-poor plasma to the specimen

Correct answer: B

Why: EDTA-associated platelet clumping causes pseudothrombocytopenia. Recollection in citrate often resolves the artifact.

Why the other options are wrong:
A — The automated count is unreliable when clumps are seen.
C — Bone marrow examination is not first-line for a specimen artifact.
D — Platelet-poor plasma does not resolve EDTA-dependent clumping.

هكذا تعقمون هواتفكم لتجنب كورونا

أثبتت الدراسات بأن الهواتف الجوالة عادة ما تكون موبوءة بالجراثيم والفيروسات التي تظل عالقة بها لأيام، وربما حتى لأسابيع.

فقد أكد المركز الاميركي للسيطرة على الامراض والوقاية منها " CDC " ان تعقيم الهواتف المحمولة يحول دون وصول فيروس كورونا المستجد "كوفيد 19" الى يديك وبالتالي الى داخل جسمك. ومع ارتفاع خطر تفشي فيروس كورونا حول العالم، ظهرت العديد من النصائح الوقائية، أهمها غسل اليدين بكثرة وتطهير الأشياء التي تلمسها اليدان باستمرار، ومن أبرزها الهاتف المحمول.

لقد أصبحت الجوالات الذكية جزءً مهما من حياتنا وضروريا لإنجاز أغلب المهام وأصبح من الطبيعي أن يرافقنا الجوال في كل مكان نذهب إليه خلال يومنا سواء كنت تحمله في يدك أو تحتفظ به في جيبك وحتى إن كنت تضعه ضمن غطاء للحماية سوف يتعرض الجوال إلى الكثير من الأوساخ والبكتيريا والغباروالفيروسات وربما أيضا فيروس كورونا المستجد "كوفيد 19" وبما أنّ لا أحد يحب أن يحمل جوالا متسخا  او مصدر عدوي يجب أن نحافظ على نظافة هذا الجوال باستمرار لكن كيف يمكننا تنظيف الجوال  الذكي دون التسبب بتلفه وماهي المواد التي يجب استخدامها.

لكن قبل أن تبدأ بتنظيف الجوال يجب ان تضع في عين الاعتبار أنّ الجوال الذكي ليس مصنوعا من مادة واحدة فهو يحوي أجزاءً مصنوعة من المعدن وأجزاءً أخرى مصنوعة من الزجاج بالإضافة إلى وجود قطع أخرى مصنوعة من البلاستك وحيث أنّ لكل مادة خصائصها المميزة يجب أن تكون حذرا كي لا تستعمل موادً تسبب تلف بعض الأجزاء او فقدان لونها فعند تنظيف الأجزاء الزجاجية كالشاشة مثلا يجب الانتباه إلى أن الشاشة الزجاجية للجوال ليست كالزجاج العادي في المنزل ولذلك عليك تجنب مسحها باستخدام ملمع الزجاج المستخدم لتنظيف المرايا لأنه قد يتسبب بتلف طبقة الحماية التي تغطي شاشة الجوال وأيضا يجب ألا تستخدم السوائل لتنظيف الأجزاء المعدنية حتى لا تتسبب بتشكل طبقة من الصدأ على المعدن مما يؤدي إلى إزالة اللمعان عن المعدن المصقول.

وفيما يلي الطريقة المثلى المختصرة لتنظيف هاتفك:

1.     اطفئ الهاتف.
2. استخدم قطع تنظيف ناعمة لا تؤثر على ملمس الهاتف، وقادرة على التقاط أكبر عدد من الجراثيم، استغل الجزء الجاف من القطعة عند التنطيف، وتأكد من غسلها قبل إعادة استخدامها مستقبلا.
3. إستخدم كحول التنظيف تأكد أن المحلول مخفف، ولا تضع الكحول على الهاتف مباشرة، بل ضع قليلا منها على جزء جاف من قطعة التنظيف، ثم ابدأ بتنظيف الهاتف بلين، يمكنك أيضا استخدام الصابون والماء لتنظيف الهاتف.
4.  احذر المواد والمحاليل الكاشطة التي قد تؤثر على ملمس هاتفك مثل منظف النوافذ والخل أو بيروكسيد الهيدروجين، لأنها قد تزيل الطبقة اللامعة من الهاتف.
5. حافظ على هاتفك نظيفا قدر الإمكان، خاصة في الأماكن المليئة بالجراثيم مثل المراحيض العامة، وعقم الجهاز مرتين يوميا على الأقل.

وفيما يلي الطريقة المثلى بشيئ من التفصيل لتنظيف هاتفك:

تنظيف شاشة الجوال المحمول

بعد أن أصبحت أغلب الجوالات المحمولة تعمل بتقنية اللمس أصبح من المألوف أن تجد شاشة جوالك متسخة بآثار الأصابع والبصمات بالإضافة إلى احتمال وجود أوساخ أخرى في حال استخدامك الجوال عند وجود بعض الأوساخ على يديك لكن لحسن الحظ فطريقة تنظيف الشاشة بسيطة للغاية، حيث أن كل ما تحتاج إليه هو قطعةٌ من القماش الدقيق (Microfiber) والتي قد تكون مرفقة مع بعض الجوالات وهو نفس نوع القماش المرفق مع النظارات والذي يستخدم لمسح عدسات النظارات، وقبل أن تبدأ بتنظيف الشاشة من المفضل أن تقوم بإطفاء الجوال حيث أن الأوساخ تظهر بشكل أوضح عندما تكون الشاشة مطفأة.

خطوات تنظيف الشاشة

باستخدام القماش الدقيق قم بمسح الشاشة بشكل دوائر صغيرة حيث أن هذه الطريقة تساعد في إزالة أغلب الأوساخ الموجودة على شاشة الجوال كما أنها تقلل من ظهور الخطوط والآثار الناتجة عن المسح بحيث تظهر الشاشة بعد مسحها بشكل أفضل.

في حال كان هناك بعض الأوساخ العالقة على الشاشة ولم تزل بعد عملية المسح الأولى يمكنك تبليل قطعة قماش قطنية بعدة قطرات من الماء وإعادة مسح الشاشة بنفس الطريقة السابقة بشكل دوائر صغيرة على الشاشة، لكن قبل القيام بهذه الخطوة يجب الانتباه إلى بعض قطع القماش الدقيق المستخدمة لمسح الجوالات تتطلب استخدام بضعة قطرات من الماء وفي هذه الحلة لا داعي لاستخدام قطعة قماش قطنية رطبة، بالإضافة إلى انه من المفضل عندما تريد مسح الشاشة بالماء ان تستخدم قطعة قماش رطبة مخصصة لتنظيف الجوالات أو استخدام الماء المقطر لترطيب القماش حيث أن ماء الصنبور قد يحوي شوائب تؤدي إلى خدش الشاشة.

في النهاية يجب أن تعيد مسح الشاشة مجددا باستخدام القماش الدقيق ثم ترك الجوال حتى يجف تماماً في حال وجود آثار رطبة على الشاشة.

بالنسبة لقطعة القماش الدقيقة ونظرا لكون بعضها مرتفع الثمن يمكنك بعد الانتهاء من تنظيف الشاشة أن تقوم بنقعها قليلا في ماء دافئ حيث أن الحرارة تقوم بفتح المسامات في أنسجة القماش ثم دعكها قليلا بلطف ثم وضعها في مكان جاف حتى تجف بشكل كامل، كما يجب الانتباه إلى ضرورة عدم استخدام القماش الدقيق لتنظيف أي شاشة في حال لم يكن جافا بشكل كامل، لذا إن كنت في عجلة من أمرك وتريد تنظيف شاشة ثانية يمكنك استخدام مجفف الشعر لتجفيف قطعة القماش الدقيق بسرعة.

تعقيم الجوال باستخدام الجل المعقم لليدين

تعد هذه الطريقة فعالة لتنظيف الجوال كما أنها تفيد لتعقيمه من الجراثيم حيث أن الجوال المحمول يعد من أكثر الأجسام الحاوية على الجراثيم في المنزل، وبما أن الجوال المحمول يبقى بين يديك طوال الوقت فمن الضروري القيام بهذه العملية بين الحين والآخر، وتعد هذه الطريقة بسيطة فكل ما تحتاج إليه أن تضع القليل من الجيل على منديل ورقي وتقوم بمسح الشاشة والجوال ثم تقوم بمسح الجوال باستخدام قطعة من القماش الدقيق لإزالة لطخات الجيل المتبقية على الجوال في حال بقي أيّ منها.

تعقيم الجوال باستخدام الكحول

تعد هذه الطريقة فعالة بشكل كبير للقضاء على الجراثيم كما أنها تزيل آثار البصمات عن الشاشة بالإضافة لأي أوساخ أخرى قد تكون عالقة عليها، ولاستخدام هذه الطريقة كل ما تحتاج إليه هو القليل من الكحول والماء المقطر ومِرَش ماء كالمرشات المستخدمة في علب العطر وقطعة من القماش الدقيق، حيث يجب عليك اولاً خلط الكحول والماء ضمن المرش ثم رش القليل من الكحول المخفف على قطعة القماش الدقيق بعدها تقوم بمسح كامل الشاشة والجوال باستخدام قطعة القماش المبلولة بالكحول وتركه حتى يجف.

يجب أن ننوه أنّ هناك بعض الشركات مثل شركة أبل تنصح باستخدام الكحول النقي لتعقيم الجوال فيما ينصح آخرون بمزج الكحول مع الماء المقطر، ومن المهم أيضا أن تعلم أن بإمكانك تنظيف الجوال دون استخدام المرش في هذه الطريقة لكن استخدامه يضمن أنك ستضع كمية قليلة من السائل ويجب الانتباه أنّ رش السائل يجب أن يتم على قطعة القماش حصرا وليس على الجوال تجنبا لدخول الكحول إلى داخل الجوال مما قد يسبب تلفه. (ولكن احذر فاستخدام الكحول قد يؤثر على لون الجوال مع الاستخدام المستمر).

تعقيم جوالك بالأشعة فوق البنفسجية

هناك أجهزة خاصة مثل جهاز Phone Soap والتي تستخدم الأشعة فوق البنفسجية لتعقيم الجوال المحمول والقضاء على الجراثيم كما أنها تحوي منفذاَ للطاقة ما يعني أن بإمكانك شحن الجوال أيضا أثناء تعقيمه كما أنّ بعضها يأتي مزوداً بسماعات خارجية لكي ترفع من مستوى الصوت عند سماع الموسيقا، ورغم أنّ هذه الطريقة فعالة إلا أنها قد تكون مكلفة نوعاً ما.