The H/O medical abbreviation most often means history of, a quick way to flag a condition, event or procedure from a patient's past, as in "h/o asthma" or "h/o fall." It is usually written in lower case, h/o, right before the condition it describes.
In some hospitals the same letters also refer to hematology and oncology, the specialty that treats blood disorders and cancer, more often written Heme/Onc. The two meanings separate quickly when you check what comes right after the letters. This page shows both, with sample lines, and explains how h/o relates to HX and PMH.
At a glance
Stands for
History of (most common)Other meanings
Hematology and oncology, usually written Heme/OncWritten as
h/o, H/O, hx ofWhere you see it
Opening line of notes, problem lists, referralsRelated terms
Do not confuse with
C/O, complains of
How the H/O medical abbreviation reads as history of
When h/o comes right before a diagnosis or event, it means the patient has had that condition or experience at some point in the past. Sometimes the condition is still present and being managed, as with h/o high blood pressure, and sometimes it is over, as with h/o kidney stones. The letters alone do not say which; the rest of the note does.
Writers use it to give context quickly. A chest pain workup reads very differently in someone with h/o heart attack than in someone with no such past, so the first line of many notes lists the most relevant history right away.
Sample lines with history of
Emergency note opener: "62M with h/o HTN, DM2 and CAD presents with chest pain x 2 hours." In plain words: a 62 year old man with a past of high blood pressure, type 2 diabetes and coronary artery disease came in with two hours of chest pain.
| Line | Plain meaning |
|---|---|
| h/o falls | Has fallen before, a safety flag for staff |
| h/o MRSA | Has had a resistant staph infection in the past |
| h/o CVA | Has had a stroke |
| no h/o bleeding | Has never had a bleeding problem |
| FH: mother with h/o breast cancer | Family history, about a relative, not the patient |
H/O as hematology and oncology
The second meaning is a specialty. Hematology deals with blood and blood forming organs, such as anemia, clotting problems and blood cancers. Oncology deals with cancer care. Many practices combine them, and staff often call the service Heme/Onc. In that use, H/O may appear in a referral, a clinic name on a schedule or a consult request, such as "Consult H/O re: new anemia."
The clue is grammar. History of is followed by a condition. The specialty sense usually appears where a team or clinic name would go, after words like consult, referred to, follow up with or seen by.
Medical abbreviation h/o versus HX, PMH and S/P
Several abbreviations describe the past, and each has its own job.
- HX means history in general. A note may say "Hx: asthma" or use it in compounds like PMHx.
- PMH is past medical history, the formal section that lists all major conditions.
- h/o is used inline, inside a sentence, to point to one item from that history.
- S/P, status post, refers to something done or happened, often a procedure, as in s/p appendectomy.
A related line, c/o for complains of, describes current symptoms rather than past ones, which is why the two often appear in the same opening sentence.
Using h/o well when you chart
For students and scribes, h/o is a time saver in the first line of a note, the HPI and problem lists. Keep it to items that matter for the current visit, and spell out the condition after it rather than stacking more abbreviations when the reader might be a patient. If a condition is fully resolved, adding a word such as resolved or remote helps the next reader.
The chart abbreviations section gathers other note openers such as PMH, HPI and C/O.
History items in a chart are a summary written for the care team. If something listed about your past looks wrong, mention it at your next visit, and your clinician can check and correct the entry.
Frequently asked questions
How is h/o used in a chart?
It usually means history of. For example, h/o asthma means the patient has had asthma in the past, and it may still be an active condition.
Can H/O mean hematology oncology?
Yes. Some hospitals use H/O for the hematology and oncology service, though Heme/Onc is more common. It appears where a team or clinic name would go, such as a referral.
What is the difference between h/o and HX?
Both relate to history. Hx stands for history in a broad sense and heads sections, while h/o is used inside a sentence before one particular condition.
What does no h/o mean?
It means no history of. For example, no h/o seizures means the patient has never had a seizure as far as the record shows.