Medical Terminology and Coding Standards

Standard Nomenclature Systems

SNOMED CT (Systematized Nomenclature of Medicine - Clinical Terms)

Purpose: Comprehensive clinical terminology for electronic health records

Coverage:

• Clinical findings
• Symptoms
• Diagnoses
• Procedures
• Body structures
• Organisms
• Substances
• Pharmaceutical products
• Specimens

Structure:

• Concepts with unique identifiers
• Descriptions (preferred and synonyms)
• Relationships between concepts
• Hierarchical organization

Example:

• Concept: Myocardial infarction
• SNOMED CT code: 22298006
• Parent: Heart disease
• Children: Acute myocardial infarction, Old myocardial infarction

Benefits:

• Enables semantic interoperability
• Supports clinical decision support
• Facilitates data analytics
• International standard

LOINC (Logical Observation Identifiers Names and Codes)

Purpose: Universal code system for laboratory and clinical observations

Components of LOINC code:

1. Component (analyte or measurement): What is measured
2. Property: What characteristic (mass, volume, etc.)
3. Timing: When measured (point in time, 24-hour)
4. System: Specimen or system (serum, urine, arterial blood)
5. Scale: Type of result (quantitative, ordinal, nominal)
6. Method: How measured (when relevant to interpretation)

Examples:

• Glucose [Mass/volume] in Serum or Plasma: 2345-7

  • Component: Glucose
  • Property: Mass concentration
  • Timing: Point in time
  • System: Serum/Plasma
  • Scale: Quantitative

• Hemoglobin A1c/Hemoglobin.total in Blood: 4548-4

  • Component: Hemoglobin A1c/Hemoglobin.total
  • Property: Mass fraction
  • Timing: Point in time
  • System: Blood
  • Scale: Quantitative

LOINC Parts:

• Document types
• Survey instruments
• Clinical attachments
• Radiology codes
• Pathology codes

ICD-10-CM (International Classification of Diseases, 10th Revision, Clinical Modification)

Purpose: Diagnosis and procedure coding for billing, epidemiology, and health statistics

Structure:

• Alphanumeric codes (3-7 characters)
• First character: letter (except U)
• Characters 2-3: numbers
• Characters 4-7: alphanumeric (decimal after 3rd character)
• Laterality, severity, encounter type specified

Code structure example:

• S72.001A: Fracture of unspecified part of neck of right femur, initial encounter
  • S: Injury category
  • 72: Femur
  • 001: Unspecified part of neck
  • A: Initial encounter for closed fracture
  • Right side indicated by 1 in 5th position

Common categories:

• A00-B99: Infectious diseases
• C00-D49: Neoplasms
• E00-E89: Endocrine, nutritional, metabolic
• F01-F99: Mental and behavioral
• G00-G99: Nervous system
• I00-I99: Circulatory system
• J00-J99: Respiratory system
• K00-K95: Digestive system
• M00-M99: Musculoskeletal
• N00-N99: Genitourinary
• S00-T88: Injury, poisoning

Seventh character extensions:

• A: Initial encounter
• D: Subsequent encounter
• S: Sequela

Placeholder X:

• Used when code requires 7th character but fewer than 6 characters
• Example: T36.0X5A (Adverse effect of penicillins, initial encounter)

Combination codes:

• Single code describing two diagnoses or diagnosis with manifestation
• Example: E11.21 (Type 2 diabetes with diabetic nephropathy)

CPT (Current Procedural Terminology)

Purpose: Procedure and service coding for billing

Maintained by: American Medical Association (AMA)

Categories:

• Category I: Procedures and services (5-digit numeric codes)
• Category II: Performance measurement (4 digits + F)
• Category III: Emerging technology (4 digits + T)

Category I Sections:

• 00100-01999: Anesthesia
• 10000-69990: Surgery
• 70000-79999: Radiology
• 80000-89999: Pathology and Laboratory
• 90000-99999: Medicine
• 99000-99607: Evaluation and Management (E/M)

E/M Codes (commonly used):

• 99201-99215: Office visits (new and established)
• 99221-99239: Hospital inpatient services
• 99281-99285: Emergency department visits
• 99291-99292: Critical care
• 99304-99318: Nursing facility services

Modifiers:

• Two-digit codes appended to CPT codes
• Indicate service was altered but not changed
• Examples:
  • -25: Significant, separately identifiable E/M service
  • -50: Bilateral procedure
  • -59: Distinct procedural service
  • -76: Repeat procedure by same physician
  • -RT/LT: Right/Left side

RxNorm

Purpose: Normalized names for clinical drugs and drug delivery devices

Structure:

• Includes brand and generic names
• Dose forms
• Strengths
• Links to other drug vocabularies (NDC, SNOMED CT)

Example:

• Concept: Amoxicillin 500 MG Oral Capsule
• RxNorm CUI: 308191
• Ingredients: Amoxicillin
• Strength: 500 MG
• Dose Form: Oral Capsule

Medical Abbreviations

Acceptable Standard Abbreviations

Time:

• q: every (q4h = every 4 hours)
• qd: daily (avoid - use "daily")
• bid: twice daily
• tid: three times daily
• qid: four times daily
• qhs: at bedtime
• prn: as needed
• ac: before meals
• pc: after meals
• hs: at bedtime

Routes:

• PO: by mouth (per os)
• IV: intravenous
• IM: intramuscular
• SC/SQ/subcut: subcutaneous
• SL: sublingual
• PR: per rectum
• NG: nasogastric
• GT: gastrostomy tube
• TD: transdermal
• inh: inhaled

Frequency:

• stat: immediately
• now: immediately
• continuous: without interruption
• PRN: as needed

Laboratory:

• CBC: complete blood count
• BMP: basic metabolic panel
• CMP: comprehensive metabolic panel
• LFTs: liver function tests
• PT/INR: prothrombin time/international normalized ratio
• PTT/aPTT: partial thromboplastin time/activated PTT
• ESR: erythrocyte sedimentation rate
• CRP: C-reactive protein
• ABG: arterial blood gas
• UA: urinalysis
• HbA1c: hemoglobin A1c

Diagnoses:

• HTN: hypertension
• DM: diabetes mellitus
• CHF: congestive heart failure
• CAD: coronary artery disease
• COPD: chronic obstructive pulmonary disease
• CVA: cerebrovascular accident
• MI: myocardial infarction
• PE: pulmonary embolism
• DVT: deep vein thrombosis
• UTI: urinary tract infection
• CKD: chronic kidney disease
• ESRD: end-stage renal disease

Physical Examination:

• HEENT: head, eyes, ears, nose, throat
• PERRLA: pupils equal, round, reactive to light and accommodation
• EOMI: extraocular movements intact
• JVP: jugular venous pressure
• RRR: regular rate and rhythm
• CTAB: clear to auscultation bilaterally
• BS: bowel sounds or breath sounds (context dependent)
• NT/ND: non-tender, non-distended
• FROM: full range of motion

Vital Signs:

• BP: blood pressure
• HR: heart rate
• RR: respiratory rate
• T or Temp: temperature
• SpO2: oxygen saturation
• Wt: weight
• Ht: height
• BMI: body mass index

Do Not Use Abbreviations (Joint Commission)

Prohibited abbreviations:

Abbreviation	Intended Meaning	Problem	Use Instead
U	Unit	Mistaken for 0, 4, or cc	Write "unit"
IU	International Unit	Mistaken for IV or 10	Write "international unit"
Q.D., QD, q.d., qd	Daily	Mistaken for each other	Write "daily"
Q.O.D., QOD, q.o.d., qod	Every other day	Mistaken for QD or QID	Write "every other day"
Trailing zero (X.0 mg)	X mg	Decimal point missed	Never write zero after decimal (write X mg)
Lack of leading zero (.X mg)	0.X mg	Decimal point missed	Always write zero before decimal (write 0.X mg)
MS, MSO4, MgSO4	Morphine sulfate or magnesium sulfate	Confused for each other	Write "morphine sulfate" or "magnesium sulfate"

Additional problematic abbreviations:

• µg: micrograms (mistaken for mg) → write "mcg"
• cc: cubic centimeters → write "mL"
• hs: half-strength or hour of sleep → write "half-strength" or "bedtime"
• TIW: three times a week → write "three times weekly"
• SC, SQ: subcutaneous → write "subcut" or "subcutaneous"
• D/C: discharge or discontinue → write full word
• AS, AD, AU: left ear, right ear, both ears → write "left ear," "right ear," "both ears"
• OS, OD, OU: left eye, right eye, both eyes → write "left eye," "right eye," "both eyes"

Medication Nomenclature

Generic vs. Brand Names

Best practice: Use generic names in medical documentation

Examples:

• Acetaminophen (generic) vs. Tylenol (brand)
• Ibuprofen (generic) vs. Advil, Motrin (brand)
• Atorvastatin (generic) vs. Lipitor (brand)
• Metformin (generic) vs. Glucophage (brand)
• Lisinopril (generic) vs. Zestril, Prinivil (brand)

When to include brand:

• Patient education (recognition)
• Novel drugs without generic
• Narrow therapeutic index drugs with bioequivalence issues
• Biologic products

Dosage Forms

Solid oral:

• Tablet
• Capsule
• Caplet
• Chewable tablet
• Orally disintegrating tablet (ODT)
• Extended-release (ER, XR, SR)
• Delayed-release (DR)

Liquid oral:

• Solution
• Suspension
• Syrup
• Elixir
• Drops

Parenteral:

• Solution for injection
• Powder for injection (reconstituted)
• Intravenous infusion
• Intramuscular injection
• Subcutaneous injection

Topical:

• Cream
• Ointment
• Gel
• Lotion
• Paste
• Patch (transdermal)
• Foam
• Spray

Other:

• Suppository (rectal, vaginal)
• Inhaler (MDI, DPI)
• Nebulizer solution
• Ophthalmic (drops, ointment)
• Otic (drops)
• Nasal spray

Prescription Writing Elements

Complete prescription includes:

1. Patient name and DOB
2. Date
3. Medication name (generic preferred)
4. Strength/concentration
5. Dosage form
6. Quantity to dispense
7. Directions (Sig)
8. Number of refills
9. Prescriber signature and credentials
10. DEA number (for controlled substances)

Sig (Directions for use):

• Clear, specific instructions
• Route of administration
• Frequency
• Duration (if applicable)
• Special instructions

Example:

• "Take one tablet by mouth twice daily with food for 10 days"
• "Apply thin layer to affected area three times daily"
• "Instill 1 drop in each eye every 4 hours while awake"

Anatomical Terminology

Directional Terms

Superior/Inferior:

• Superior: toward the head
• Inferior: toward the feet
• Cranial: toward the head
• Caudal: toward the tail/feet

Anterior/Posterior:

• Anterior: toward the front
• Posterior: toward the back
• Ventral: toward the belly
• Dorsal: toward the back

Medial/Lateral:

• Medial: toward the midline
• Lateral: away from the midline

Proximal/Distal:

• Proximal: closer to the trunk or point of origin
• Distal: farther from the trunk or point of origin

Superficial/Deep:

• Superficial: toward the surface
• Deep: away from the surface

Body Planes

Sagittal plane: Divides body into right and left

• Midsagittal: exactly through midline
• Parasagittal: parallel to midline

Coronal (frontal) plane: Divides body into anterior and posterior

Transverse (axial) plane: Divides body into superior and inferior

Anatomical Position

• Standing upright
• Feet parallel
• Arms at sides
• Palms facing forward
• Head facing forward

Regional Terms

Head and Neck:

• Cephalic: head
• Frontal: forehead
• Orbital: eye
• Nasal: nose
• Oral: mouth
• Cervical: neck
• Occipital: back of head

Trunk:

• Thoracic: chest
• Abdominal: abdomen
• Pelvic: pelvis
• Lumbar: lower back
• Sacral: sacrum

Extremities:

• Brachial: arm
• Antebrachial: forearm
• Carpal: wrist
• Manual: hand
• Digital: fingers/toes
• Femoral: thigh
• Crural: leg
• Tarsal: ankle
• Pedal: foot

Laboratory Units and Conversions

Common Laboratory Units

Hematology:

• RBC: × 10⁶/μL or × 10¹²/L
• WBC: × 10³/μL or × 10⁹/L
• Hemoglobin: g/dL or g/L
• Hematocrit: % or fraction
• Platelets: × 10³/μL or × 10⁹/L
• MCV: fL
• MCHC: g/dL or g/L

Chemistry:

• Glucose: mg/dL or mmol/L
• BUN: mg/dL or mmol/L
• Creatinine: mg/dL or μmol/L
• Sodium, potassium, chloride: mEq/L or mmol/L
• Calcium: mg/dL or mmol/L
• Albumin: g/dL or g/L
• Bilirubin: mg/dL or μmol/L
• Cholesterol: mg/dL or mmol/L

Therapeutic Drug Levels:

• Usually: mcg/mL, ng/mL, or μmol/L

Unit Conversions (Selected)

Glucose:

• mg/dL ÷ 18 = mmol/L
• mmol/L × 18 = mg/dL

Creatinine:

• mg/dL × 88.4 = μmol/L
• μmol/L ÷ 88.4 = mg/dL

Bilirubin:

• mg/dL × 17.1 = μmol/L
• μmol/L ÷ 17.1 = mg/dL

Cholesterol:

• mg/dL × 0.0259 = mmol/L
• mmol/L × 38.67 = mg/dL

Hemoglobin:

• g/dL × 10 = g/L
• g/L ÷ 10 = g/dL

Grading and Staging Systems

Cancer Staging (TNM)

T (Primary Tumor):

• TX: Cannot be assessed
• T0: No evidence of primary tumor
• Tis: Carcinoma in situ
• T1-T4: Size and/or extent of primary tumor

N (Regional Lymph Nodes):

• NX: Cannot be assessed
• N0: No regional lymph node metastasis
• N1-N3: Involvement of regional lymph nodes

M (Distant Metastasis):

• M0: No distant metastasis
• M1: Distant metastasis present

Stage Grouping:

• Stage 0: Tis N0 M0
• Stage I-III: Various T and N combinations, M0
• Stage IV: Any T, any N, M1

NYHA Heart Failure Classification

• Class I: No limitation. Ordinary physical activity does not cause symptoms
• Class II: Slight limitation. Comfortable at rest, ordinary activity causes symptoms
• Class III: Marked limitation. Comfortable at rest, less than ordinary activity causes symptoms
• Class IV: Unable to carry out any physical activity without symptoms. Symptoms at rest

Child-Pugh Score (Liver Disease)

Parameters: Bilirubin, albumin, INR, ascites, encephalopathy

Classes:

• Class A (5-6 points): Well-compensated
• Class B (7-9 points): Significant functional compromise
• Class C (10-15 points): Decompensated

Glasgow Coma Scale

Eye Opening (1-4):

• 4: Spontaneous
• 3: To speech
• 2: To pain
• 1: None

Verbal Response (1-5):

• 5: Oriented
• 4: Confused
• 3: Inappropriate words
• 2: Incomprehensible sounds
• 1: None

Motor Response (1-6):

• 6: Obeys commands
• 5: Localizes pain
• 4: Withdraws from pain
• 3: Abnormal flexion
• 2: Extension
• 1: None

Total Score: 3-15 (3 = worst, 15 = best)

• Severe: ≤8
• Moderate: 9-12
• Mild: 13-15

Medical Prefixes and Suffixes

Common Prefixes

• a-/an-: without, absence (anemia, aphasia)
• brady-: slow (bradycardia)
• dys-: abnormal, difficult (dyspnea, dysuria)
• hyper-: excessive, above (hypertension, hyperglycemia)
• hypo-: below, deficient (hypotension, hypoglycemia)
• poly-: many (polyuria, polydipsia)
• tachy-: fast (tachycardia, tachypnea)
• macro-: large (macrocephaly)
• micro-: small (microcephaly)
• hemi-: half (hemiplegia)
• bi-/di-: two (bilateral, diplopia)

Common Suffixes

• -algia: pain (arthralgia, neuralgia)
• -ectomy: surgical removal (appendectomy, cholecystectomy)
• -emia: blood condition (anemia, leukemia)
• -itis: inflammation (appendicitis, arthritis)
• -oma: tumor (carcinoma, melanoma)
• -osis: abnormal condition (cirrhosis, osteoporosis)
• -pathy: disease (neuropathy, nephropathy)
• -penia: deficiency (thrombocytopenia, neutropenia)
• -plasty: surgical repair (rhinoplasty, angioplasty)
• -scopy: visual examination (colonoscopy, bronchoscopy)
• -stomy: surgical opening (colostomy, tracheostomy)

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This reference provides comprehensive medical terminology, coding systems, abbreviations, and nomenclature standards. Use these guidelines to ensure accurate, standardized clinical documentation.