Plain English

Medical words on reports, explained

Reports and letters are written for the next doctor, not for you. These are the words people look up most, in plain English. They explain the word, not what it means for your own body; for that, ask the doctor who ordered the test.

Words about results

What the lab or the scan found, and whether it was expected.

Unremarkable: Normal. Nothing was found that was worth remarking on. On a scan report it is one of the best words you can read.
Within normal limitsalso WNL: The result falls inside the range expected for healthy people.
Negative: The test did not find what it was looking for. For most tests this is the result people hope for.
Positive: The test found what it was looking for. Whether that is good or bad news depends on the test: a positive pregnancy test and a positive infection test mean very different things.
Reference rangealso Normal range, Reference interval: The range where results from most healthy people fall, usually the middle 95%. About 1 in 20 healthy people land just outside it on any single test, so a result slightly outside is common.
H or L flagalso High, Low, Abnormal flag: A mark next to a result that sits above (H) or below (L) the reference range. It says the number is outside the usual range, not that something is wrong. How far outside, and the trend, matter more.
Borderline: The result is close to the edge of the range, either just inside or just outside. Doctors often repeat the test or watch the trend.
Critical valuealso Panic value, Critical result: A result so far outside the range that the lab contacts the doctor straight away. If a report says critical, call your doctor's office the same day.
Inconclusivealso Indeterminate, Equivocal: The test could not give a clear answer either way. It is usually repeated or followed by a different test.
Non-specificalso Nonspecific: A finding that can have many different causes, most of them harmless, so on its own it does not point to any one thing.
Benign: Not cancer. A benign growth does not spread to other parts of the body.
Malignant: Cancerous: able to grow into nearby tissue or spread. It is a word to discuss with your doctor in person, with time for questions.

Words about what was seen

Common words in scan and X-ray reports.

Lesion: Any area of tissue that looks different from the tissue around it. It is a general word and does not mean cancer. Many lesions are harmless.
Nodule: A small, rounded lump or spot. Most small nodules, for example in the lungs or the thyroid, are harmless; size and change over time guide what happens next.
Cyst: A small sac filled with fluid. Simple cysts are very common and usually harmless.
Mass: A lump of tissue, usually larger than a nodule. The word describes size and shape, not what the tissue is.
Incidental findingalso Incidentaloma: Something noticed by chance while looking for something else. Most are harmless; some are worth a follow-up check.
Opacity: An area on an X-ray or CT that looks whiter or denser than expected. It describes what the image looks like, and has many possible causes, from a small scar to an infection.
Calcification: A small deposit of calcium in tissue, which shows up bright on X-rays and scans. Many are harmless and come with age or old, healed injuries.
Effusion: Extra fluid collected in a space in the body, such as around a lung (pleural effusion) or in a joint.
Edemaalso Oedema: Swelling caused by fluid in the tissues, often in the legs or ankles.
Atelectasis: A small part of a lung that is not fully filled with air. Mild atelectasis is common on scans, for example after surgery or in someone who has been lying down.
Degenerative changes: Wear and tear, usually in joints or the spine. It is very common with age and is often seen on scans of people who have no pain.
Stenosis: Narrowing of a tube or passage in the body, such as a blood vessel or the spinal canal.
Hypertrophy: Enlargement of an organ or tissue because its cells have grown bigger, for example a thickened heart muscle.
Atrophy: Shrinking of a tissue or organ. Some atrophy is a normal part of ageing.
Hyperdense / hypodensealso Hyperechoic, Hypoechoic, Hyperintense, Hypointense: Brighter (hyper-) or darker (hypo-) than the tissue around it on a scan. Dense and attenuation are CT words, echoic is ultrasound, intense is MRI. They describe the picture, not a diagnosis.
Enhancement: An area that lights up after contrast dye is given during a CT or MRI. It shows where blood flow is, and is read together with everything else on the scan.
Artifactalso Artefact: Something on an image that is not really in the body, such as a blur from movement or a streak from metal. Radiologists mention it so it is not mistaken for a finding.

Where and which side

Words that place something in the body.

Bilateral / unilateral: Bilateral means on both sides of the body; unilateral means on one side only.
Anterior / posterior: Anterior means towards the front of the body; posterior means towards the back.
Proximal / distal: Proximal means closer to the center of the body or to where a limb attaches; distal means further away. Your wrist is distal to your elbow.
Superior / inferior: Superior means higher up, towards the head; inferior means lower down. They are directions, not judgments.

How long and how much

Words about timing and size.

Acute: Started recently or came on suddenly. It describes timing, not how serious something is.
Chronic: Long-lasting, usually for three months or more. It describes duration, not danger.
Subacute: Between acute and chronic: a few weeks rather than days or many months.
Mild / moderate / severe: How marked a change is, compared with what the specialist usually sees. A mild finding is often not a reason for treatment on its own.
Stablealso Unchanged, No interval change: No change compared with an earlier test or scan. For something being watched, stable is usually reassuring.

Words in doctors' letters

What clinicians write to each other about a plan.

Impressionalso Conclusion, Summary: The short summary at the end of a scan report, where the radiologist says what the findings mean together. Read this part first.
Clinical correlation recommendedalso Correlate clinically: The radiologist is asking your own doctor to compare the finding with your symptoms, examination and history. It is a routine phrase, not a warning sign by itself.
Follow-up recommended: Another test or visit is suggested later, often to check that something has not changed. Ask when, and write the date down.
Differential diagnosisalso DDx, Differential: The list of possible explanations a doctor is still considering. Being on the list does not mean it is likely.
Rule outalso R/O: A test is being done to make sure something is not the cause. It does not mean the doctor thinks it is.
Idiopathic: No known cause has been found. It is common and does not mean something was missed.
Prognosis: The likely course or outcome of a condition. Ask your doctor what it means for you specifically.
Remission: Signs and symptoms of a disease have reduced or gone away. It can be partial or complete.
Patient denies: You said no when asked about something, for example "denies chest pain". It is standard wording and does not mean anyone doubted you.
PRN: As needed. A medicine marked PRN is taken only when a symptom appears, within the limits on the label.
BID / TID / QID: Twice a day, three times a day and four times a day, from Latin abbreviations still used on prescriptions.

Reading a blood test?

The free blood test guide explains more than 100 common tests: the typical range, what a high or low result usually means, and what to ask your doctor.

General health information, not medical advice. Ask your doctor or pharmacist what a word on your own report means for you. If a report says a result is critical, or you feel very unwell, call your doctor the same day or your local emergency number.