Medical Terminology and Coding Standards

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:

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)

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