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ASCP MLS Cheat Sheet

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Blood Banking

  • 17-22% of exam
  • ABO Rh Components Compatibility Reactions Antibody ID

Chemistry

  • 17-22% of exam
  • ABG Electrolytes Enzymes TDM Chem Formulas

Hematology

  • 17-22% of exam
  • CBC Indices Anemias WBC Morph Hemostasis Heme Formulas

Microbiology

  • 17-22% of exam
  • Gram Logic Biochemical ID AST AFB Fungi Critical Bugs

Urinalysis Fluids

  • 5-10% of exam
  • Dipstick Sediment Casts CSF Crystals

Immunology

  • 5-10% of exam
  • Antibodies Complement Serology Autoimmune Transplant

Lab Operations

  • 5-10% of exam
  • QC Rules Safety Dilutions Instrumentation Test Metrics

Quick Facts

  • Credential MLS(ASCP)
  • Owner ASCP BOC
  • Questions 100 multiple-choice
  • Time 2 hours 30 minutes
  • Format CAT
  • Pass 400 scaled
  • Scale 100-999
  • Delivery Pearson VUE
  • Calculator Onscreen
  • Fee $260

Reaction Stop BL

  • Stop transfusion; keep line open
  • Clerical check DAT Hemolysis check Notify blood bank

DAT vs IAT BL

DAT

  • Patient cells
  • In vivo coating
  • Transfusion reaction

IAT

  • Patient serum
  • In vitro reaction
  • Antibody screen
  • Cells vs serum

Blood Bank Picker BL

  • Need oxygen → RBCs ( Anemia )
  • Need platelets → Platelets ( Bleeding risk )
  • Need factors → Plasma ( Coagulopathy )
  • Need fibrinogen → Cryo ( Low fibrinogen )
  • Neonate candidate → Irradiated ( TA-GVHD risk )
  • IgA allergy → Washed ( Less plasma )

Blood Products BL

  • RBCs Oxygen capacity
  • Platelets Primary hemostasis
  • Plasma Coag factors
  • Cryo Fibrinogen rich
  • Irradiated Prevents TA-GVHD
  • Leukoreduced Less febrile risk
  • Washed Less plasma protein
  • CMV-negative Reduced CMV risk

Plasma vs Cryo BL

Plasma

  • Multiple factors
  • Warfarin reversal
  • Large volume

Cryo

  • Fibrinogen rich
  • Factor VIII
  • Small volume
  • Broad factors vs fibrinogen

ABO Rh BL

  • Group A Anti-B plasma
  • Group B Anti-A plasma
  • Group O Anti-A,B plasma
  • Group AB No ABO antibody
  • O RBC Emergency donor
  • AB plasma Universal plasma
  • Weak D D variant
  • RhIG Prevents anti-D

Transfusion Workup BL

  • Type ABO/Rh
  • Screen Unexpected antibodies
  • Panel Antibody ID
  • DAT In vivo coating
  • IAT Serum antibody test
  • Autocontrol Autoantibody clue
  • Elution Remove bound antibody
  • Crossmatch Compatibility check

ABG Map CH

  • pH decides; CO2 breathes; HCO3 metabolizes
  • pH low acid pCO2 respiratory HCO3 metabolic

Metabolic vs Respiratory CH

Metabolic

  • HCO3 primary
  • Kidney/lactate clue
  • Anion gap useful

Respiratory

  • pCO2 primary
  • Ventilation clue
  • Lung process
  • Bicarbonate vs carbon dioxide

Chem Picker CH

  • Metabolic acidosis → Anion gap ( Classify )
  • Lipid risk → LDL ( Friedewald )
  • Renal clearance → CrCl ( Timed urine )
  • Toxic alcohol → Osm gap ( Screen clue )
  • Pigment urine → Heme test ( Hb/myoglobin )
  • Drug monitoring → Trough ( Before dose )

Chem Formulas CH

  • Anion gap Na-(Cl+HCO3)
  • LDL TC-HDL-TG/5
  • Non-HDL TC-HDL
  • A/G ratio Albumin/globulin
  • Globulin Protein-albumin
  • CrCl UxV/P
  • Osm gap Measured-calculated
  • Beer law A=abc

Chem Reference CH

  • Glucose 74-100 mg/dL
  • BUN 6-20 mg/dL
  • A1C normal <5.7%
  • pH 7.35-7.45
  • pCO2 35-44 mmHg
  • HCO3 23-29 mmol/L
  • pO2 >80 mmHg
  • O2 sat >95%

Chem Interference CH

  • Hemolysis Raises potassium
  • Lipemia Photometric turbidity
  • Icterus Spectral interference
  • EDTA tube Low calcium
  • Delayed spin Low glucose
  • Air bubble ABG error
  • Clot CBC reject
  • Short draw Coag reject

Coag Pathways HE

  • PT external; aPTT internal; both common
  • PT: VII aPTT: VIII/IX Both: X/V/II/I

PT vs aPTT HE

PT

  • Extrinsic pathway
  • Factor VII
  • Warfarin monitor

aPTT

  • Intrinsic pathway
  • Factors VIII/IX
  • Heparin monitor
  • Extrinsic vs intrinsic

Heme Picker HE

  • Microcytosis → Iron studies ( Ferritin first )
  • Macrocytosis → B12/folate ( Megaloblasts )
  • Hemolysis → Retic/DAT ( Classify )
  • Bleeding history → PT/aPTT ( Pathway clue )
  • Prolonged aPTT → Mixing study ( Inhibitor? )
  • nRBCs high → Correct WBC ( >10 nRBC )

CBC Indices HE

  • RBC 4.00-6.00 x10^6/uL
  • HGB 12.0-18.0 g/dL
  • HCT 35-50%
  • MCV 76-100 fL
  • MCH 26-34 pg
  • MCHC 32-36 g/dL
  • RDW 11.5-14.5%
  • Platelets 150-450 x10^3/uL
  • WBC 3.6-10.6 x10^3/uL

Anemia Patterns HE

  • Iron deficiency Low ferritin
  • Thalassemia Target cells
  • B12 deficiency Macro-ovalocytes
  • Folate deficiency Macrocytic anemia
  • Hemolysis High retics
  • AIHA Positive DAT
  • Sickle cell HbS
  • Myelofibrosis Teardrops

Hemostasis HE

  • PT Extrinsic/common
  • aPTT Intrinsic/common
  • INR Warfarin monitor
  • Fibrinogen Common pathway substrate
  • D-dimer Fibrin breakdown
  • Mixing study Deficiency vs inhibitor
  • vWF Platelet adhesion
  • Lupus anticoagulant Phospholipid inhibitor

Gram Start MI

  • Gram, shape, catalase, oxidase, context
  • GPC: catalase GNR: oxidase Specimen source matters

Micro Picker MI

  • Gram positive cocci → Catalase ( Staph/Strep )
  • Staph suspected → Coagulase ( S aureus )
  • GNR enteric → Oxidase ( Enterics negative )
  • Meningitis CSF → Critical report ( STAT )
  • AFB suspected → Acid-fast stain ( Mycobacteria )
  • Yeast ID → Germ tube ( C albicans )

Gram Logic MI

  • Staph Catalase positive
  • Strep Catalase negative
  • S aureus Coagulase positive
  • Enterococcus Bile esculin positive
  • Neisseria Oxidase positive diplococci
  • Enterics Oxidase negative rods
  • Pseudomonas Oxidase positive rod
  • Vibrio Curved oxidase positive

Micro ID MI

  • E coli Indole positive
  • Klebsiella Mucoid lactose fermenter
  • Proteus Swarming urease positive
  • Salmonella H2S motile
  • Shigella Nonmotile NLF
  • Listeria Tumbling motility
  • Campylobacter Curved microaerophile
  • Bacteroides Anaerobic GNR

AST Resistance MI

  • MRSA mecA/PBP2a
  • VRE vanA/vanB
  • ESBL Cephalosporin resistance
  • CRE Carbapenem resistance
  • D-test Inducible clindamycin
  • MIC Lowest inhibition
  • S Likely effective
  • R Likely ineffective

Transudate vs Exudate UR

Transudate

  • Systemic pressure
  • Low protein
  • CHF/cirrhosis

Exudate

  • Inflammation
  • High protein
  • Infection/malignancy
  • Pressure vs inflammation

Urine Sediment UR

  • RBC cast Glomerular bleeding
  • WBC cast Renal inflammation
  • Granular cast Tubular injury
  • Waxy cast Chronic renal disease
  • Fatty cast Nephrotic syndrome
  • Hyaline cast Nonspecific
  • Nitrite Nitrate reducers
  • LE WBC enzyme

Body Fluids UR

  • CSF cells Process rapidly
  • Bacterial CSF Low glucose
  • Viral CSF Lymphocyte predominance
  • Transudate Systemic imbalance
  • Exudate Inflammation leak
  • Urate Needle negative
  • CPPD Rhomboid positive
  • Oxalate Envelope crystals

Screen vs Confirm IM

Screen

  • High sensitivity
  • Initial result
  • May false positive

Confirm

  • Higher specificity
  • Supplemental test
  • Final interpretation
  • Catch vs verify

Immunology Serology IM

  • IgG Placenta crossing
  • IgM Primary response
  • IgA Mucosal defense
  • IgE Allergy parasite
  • C3/C4 low Complement consumption
  • ANA Sensitive nonspecific
  • Anti-dsDNA SLE specific
  • Anti-CCP RA specific

Infectious Serology IM

  • HBsAg Current HBV
  • Anti-HBs HBV immunity
  • Anti-HBc IgM Acute HBV
  • Anti-HBc total Natural exposure
  • HIV screen Ag/Ab combo
  • HIV step 2 Differentiation immunoassay
  • HIV step 3 HIV-1 NAT if non-reactive/indeterminate
  • RPR/VDRL Nontreponemal screen
  • TP-PA Treponemal confirm

Core Four OP

  • BB, Chem, Heme, Micro carry weight
  • Each 17-22% Support domains 5-10% Review mixed cases

Sensitivity vs Specificity OP

Sensitivity

  • Detects disease
  • Fewer false negatives
  • Screening strength

Specificity

  • Detects absence
  • Fewer false positives
  • Confirmatory strength
  • Rule out vs rule in

Exam Model OP

  • CAT Adaptive difficulty
  • No skipping Answer each item
  • Flagging Review if time
  • Field tests Unscored hidden items
  • Score Psychometric scale
  • Pass 400 minimum
  • Result Preliminary screen
  • Official Within four business days

QC vs QA OP

QC

  • Run-level control
  • Analytic monitoring
  • Accept/reject run

QA

  • System process
  • Continuous improvement
  • Pre-to-postanalytic
  • Control run vs system

Domain Weights OP

  • Blood bank 17-22%
  • Chemistry 17-22%
  • Hematology 17-22%
  • Microbiology 17-22%
  • Urinalysis 5-10%
  • Immunology 5-10%
  • Operations 5-10%
  • Core four Largest domains

Operations Core OP

  • Preanalytic Before testing
  • Analytic During testing
  • Postanalytic After testing
  • QC Method monitoring
  • QA System improvement
  • PT External challenge
  • SDS Chemical safety
  • PPE Exposure control

Test Metrics OP

  • Sensitivity TP/(TP+FN)
  • Specificity TN/(TN+FP)
  • PPV TP/(TP+FP)
  • NPV TN/(TN+FN)
  • CV SD/mean x100
  • Mean Average
  • Median Middle value
  • Mode Most frequent

Common Traps

CAT score

  • 400 is scaled ≠ Not forty percent

Question count

  • 100 total items ≠ Field tests hidden

ABO emergency

  • O RBC emergency ≠ AB plasma emergency

DAT meaning

  • In vivo coating ≠ Not free serum antibody

Short citrate

  • High anticoagulant ratio ≠ Reject coag specimen

Hemolyzed potassium

  • False high possible ≠ Correlate specimen quality

Dipstick blood

  • Hb/myoglobin possible ≠ RBCs may be absent

ANA result

  • Sensitive screen ≠ Not SLE diagnosis

Culture interpretation

  • Source drives significance ≠ Colonizer possible

QC violation

  • Do not report ≠ Troubleshoot first

Last Minute

  • 1. Core four: 17-22 each
  • 2. Support domains: 5-10 each
  • 3. CAT: no raw cutoff
  • 4. Pass: 400 scaled
  • 5. ABO first, Rh next
  • 6. DAT means coated cells
  • 7. Anion gap = Na-(Cl+HCO3)
  • 8. PT external; aPTT internal
  • 9. Sensitivity rules out disease
  • 10. Specificity rules in disease
  • 11. CSF cells process rapidly
  • 12. QC failure stops reporting