Clinical abbreviation reference
DxHx
What the abbreviations in a chart actually mean. 80 codes across 9 categories, the SOAP structure they sit inside, and the small number that mean two different things.
Reviewed 13 October 2026. 80 codes, 81 meanings.
Definition The two in the name
Dx
Diagnosis
The condition identified as the cause of the patient's presentation. Written in the assessment section of a note. Related forms you will see beside it are DDx for a differential diagnosis, the list still under consideration, and R/O for a condition being ruled out.
Hx
History
The patient's medical background. It is almost always qualified by what kind: PMH for past medical history, PSH for past surgical history, FH for family history, SH for social history. On its own it means the background generally.
Read carefully One code here means two different things
Abbreviation collisions are a documented patient-safety problem, which is why they are marked rather than quietly deduplicated. Where the reading is not obvious from context, write the word out.
- PE Physical Exam, or Pulmonary Embolism
Do not write The abbreviations The Joint Commission bans
Every accredited US hospital must keep a Do Not Use list, and these eight are the required minimum under Joint Commission standard IM.02.02.01. QD appears in the reference below because you will still meet it in older charts; write the word instead.
| Do not write | Meant | Misread as | Write instead |
|---|---|---|---|
| U, u | unit | 0 or 4 (4U read as 40), or cc | unit |
| IU | international unit | IV, or the number 10 | units |
| Q.D., QD, q.d., qd | every day | QID, four times daily | daily |
| Q.O.D., QOD, q.o.d., qod | every other day | QD or QID | every other day |
| 1.0 mg (trailing zero) | 1 mg | 10 mg when the decimal point is missed | 1 mg |
| .5 mg (no leading zero) | 0.5 mg | 5 mg when the decimal point is missed | 0.5 mg |
| MS, MSO4 | morphine sulfate | magnesium sulfate | the full drug name |
| MgSO4 | magnesium sulfate | morphine sulfate | the full drug name |
ISMP's longer error-prone list also flags SQ ("5 every") and D/C (discharge read as discontinue), both marked in the reference below. Sources: The Joint Commission, Do Not Use list; ISMP List of Error-Prone Abbreviations, Symbols, and Dose Designations (2024).
Reference The codes, by category
| Code | Stands for | In practice |
|---|---|---|
| CC | Chief Complaint | Primary reason for visit |
| FH | Family History | Hereditary conditions in relatives |
| HPI | History of Present Illness | Current problem narrative |
| Hx | History | Patient's medical background |
| LMP | Last Menstrual Period | Date of last period |
| NKA | No Known Allergies | Allergy status clear |
| NKDA | No Known Drug Allergies | Allergy status |
| PMH | Past Medical History | Prior illnesses & conditions |
| PSH | Past Surgical History | Prior operations |
| ROS | Review of Systems | Systematic symptom checklist |
| SH | Social History | Lifestyle, occupation, habits |
| Code | Stands for | In practice |
|---|---|---|
| CVA | Cerebrovascular Accident | Stroke, ischemic or hemorrhagic |
| DDx | Differential Diagnosis | List of possible diagnoses |
| DM | Diabetes Mellitus | Type 1 (autoimmune) or Type 2 (insulin resistant) |
| Dx | Diagnosis | Identified condition or disease |
| NAD | No Acute Distress | Patient appears comfortable |
| R/O | Rule Out | Exclude a diagnosis |
| WDL | Within Defined Limits | Results within normal range |
| WNL | Within Normal Limits | Normal findings |
| Code | Stands for | In practice |
|---|---|---|
| A&O | Alert & Oriented | Neurological baseline (×1–4) |
| A&O ×4 | Alert & Oriented ×4 | Person, place, time, event, neuro baseline |
| BMI | Body Mass Index | Weight/height² metric |
| BP | Blood Pressure | Systolic/diastolic mmHg |
| HR | Heart Rate | Beats per minute |
| PE | Physical Exam | Head-to-toe examination |
| RR | Respiratory Rate | Breaths per minute |
| SpO₂ | Oxygen Saturation | Pulse oximetry reading |
| Temp | Temperature | Body temperature in °F or °C |
| Code | Stands for | In practice |
|---|---|---|
| ABG | Arterial Blood Gas | pH, PaO₂, PaCO₂, HCO₃, acid-base status |
| BMP | Basic Metabolic Panel | Electrolytes, glucose, BUN, Cr |
| BUN | Blood Urea Nitrogen | Renal function marker |
| CBC | Complete Blood Count | WBC, RBC, Hgb, Hct, Plt |
| CMP | Comprehensive Metabolic Panel | BMP + LFTs |
| CT | Computed Tomography | Cross-sectional imaging |
| CXR | Chest X-Ray | Thoracic radiograph |
| EKG | Electrocardiogram | Heart rhythm tracing |
| INR | International Normalized Ratio | Clotting time measure |
| LFT | Liver Function Tests | ALT, AST, ALP, bilirubin |
| MRI | Magnetic Resonance Imaging | Soft tissue cross-section |
| UA | Urinalysis | Urine chemistry & microscopy |
| US | Ultrasound | Sonographic imaging |
| Code | Stands for | In practice |
|---|---|---|
| Abx | Antibiotics | Anti-bacterial medications |
| ASA | Aspirin | Acetylsalicylic acid |
| Epi | Epinephrine | Adrenaline, emergency med |
| Meds | Medications | Current drug regimen |
| OTC | Over-the-Counter | No prescription needed |
| Rx | Prescription / Treatment | Medication order |
| Code | Stands for | In practice |
|---|---|---|
| CPR | Cardiopulmonary Resuscitation | Emergency chest compressions |
| Foley | Foley Catheter | Indwelling urinary catheter |
| IM | Intramuscular | Into muscle tissue |
| IV | Intravenous | Into a vein |
| NGT | Nasogastric Tube | Tube via nose to stomach |
| OR | Operating Room | Surgical suite |
| SQ | Subcutaneous | Under the skin. ISMP flags SQ as error-prone: it has been misread as "5 every". Write "subcutaneous" or SUBQ. |
| Code | Stands for | In practice |
|---|---|---|
| AFib | Atrial Fibrillation | Irregular atrial rhythm |
| CAD | Coronary Artery Disease | Atherosclerotic heart disease |
| CHF | Congestive Heart Failure | Cardiac pump failure |
| DVT | Deep Vein Thrombosis | Blood clot in deep vein |
| HTN | Hypertension | High blood pressure |
| MI | Myocardial Infarction | Heart attack |
| PVD | Peripheral Vascular Disease | Arterial insufficiency |
| Code | Stands for | In practice |
|---|---|---|
| ARDS | ARDS | Acute respiratory distress syndrome |
| COPD | COPD | Chronic obstructive pulmonary disease |
| PE | Pulmonary Embolism | Clot in pulmonary artery |
| PNA | Pneumonia | Lung parenchymal infection |
| URI | Upper Respiratory Infection | Common cold / rhinopharyngitis |
| Code | Stands for | In practice |
|---|---|---|
| BID | Twice Daily | Bis in die |
| CP | Chest Pain | Thoracic discomfort |
| D/C | Discharge / Discontinue | Context-dependent. ISMP flags it: a discharge order read as "discontinue" has stopped medications early. Write the word. |
| ED | Emergency Department | ER / A&E |
| EHR | Electronic Health Record | Digital patient chart |
| HCP | Healthcare Provider | MD, DO, NP, PA, RN, etc. |
| HOH | Hard of Hearing | Hearing impairment |
| ICU | Intensive Care Unit | Critical care ward |
| NPO | Nothing by Mouth | Nil per os, fasting order |
| PRN | Pro Re Nata (As Needed) | Take only when necessary |
| Pt | Patient | The person receiving care |
| QD | Once Daily | Quaque die, every day. On The Joint Commission's Do Not Use list because it is misread as QID (four times daily). Write "daily". |
| QID | Four Times Daily | Quater in die |
| SOB | Shortness of Breath | Dyspnea |
| TID | Three Times Daily | Ter in die |
Structure The SOAP note
Most of these codes appear inside a note with four parts, in this order. Knowing which section you are reading usually settles what an ambiguous abbreviation means.
-
Subjective
What the patient reports: the complaint in their words, the history of the present illness, the review of systems.
-
Objective
What was measured or observed: vital signs, physical exam findings, laboratory and imaging results.
-
Assessment
The clinical interpretation: the working diagnosis or differential that the subjective and objective sections support.
-
Plan
What happens next: further investigation, treatment, medication changes, referral, follow-up.
Please note This is a reference card, not clinical guidance
DxHx explains what abbreviations mean in clinical documentation. It is not medical advice, it is not a substitute for professional judgement, and it does not tell you how to treat anyone. Usage varies between institutions, and local policy governs which abbreviations are permitted in a record. Several organisations maintain do-not-use lists precisely because some of these are dangerous in writing.
If you are a patient trying to understand your own notes, the person who wrote them is the right person to ask.