[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Clinical exam](https://durgical.com/en/clinical-exam/) › [General exam and vital signs](https://durgical.com/en/clinical-exam/#a-general) › Blood pressure measurement

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# Blood pressure measurement

- Vital sign

How to measure blood pressure properly with a cuff and stethoscope, and how adult readings are classified.

Updated 2026-11-01

**See it in 3D:** [Brachial artery](https://durgical.com/en/anatomy/brachial-artery/) · [Radial artery](https://durgical.com/en/anatomy/radial-artery/)

## Key points

- Adult categories (2025 AHA/ACC guideline, unchanged from 2017): normal below 120/80; elevated 120 to 129 with diastolic below 80; stage 1 130 to 139 or 80 to 89; stage 2 140 or higher, or 90 or higher.
- The cuff bladder should be at least 40% of arm circumference wide and encircle more than 80% of it; a small cuff gives falsely high readings.
- The cuff is inflated above the expected systolic pressure (estimated by feeling the radial pulse) to avoid the auscultatory gap.
- Systolic: first Korotkoff sound (phase I). Diastolic: disappearance of sounds (phase V) in adults.
- At the first visit measure both arms; a difference above 15 mmHg suggests vascular disease (coarctation, dissection, subclavian stenosis).
- Diagnosis never rests on one reading: two or three measurements on separate occasions are averaged; if the numbers fall in different categories, the higher one applies.

## What it is

Blood pressure is the force of blood against the arterial wall: systolic reflects ventricular ejection and diastolic the residual pressure during relaxation. Measuring it correctly is the basis of diagnosing hypertension, a leading cause of heart attack, stroke and kidney disease in Colombia and worldwide. Careless technique shifts the reading by several mmHg and leads to wrong diagnoses.

## Reference values

- Normal: systolic below 120 and diastolic below 80 mmHg.
- Elevated: systolic 120 to 129 with diastolic below 80 mmHg.
- Stage 1 hypertension: systolic 130 to 139 or diastolic 80 to 89 mmHg.
- Stage 2 hypertension: systolic 140 or higher, or diastolic 90 or higher mmHg.
- Pulse pressure (systolic minus diastolic): usually 30 to 40 mmHg at rest.
- Mean arterial pressure: diastolic plus one third of the pulse pressure; normal 70 to 110 mmHg.

## How to measure it

- Patient seated, back supported, feet flat and legs uncrossed, after five minutes' rest, with no recent coffee, tobacco or exercise and an empty bladder.
- Bare arm supported at heart level; choose the cuff by arm circumference.
- Place the cuff with the bladder centred over the brachial artery and its lower edge about 2.5 cm above the elbow crease.
- Feel the radial pulse, inflate until it disappears and note that number as the estimated systolic.
- Deflate, place the stethoscope over the brachial artery in the cubital fossa, not tucked under the cuff.
- Inflate above the estimated systolic and deflate slowly, at about 2 to 3 mmHg per second.
- Record systolic at the first clear sound and diastolic when the sounds disappear.
- Wait a minute and repeat; average two or three readings and record the arm, position and method.

## Adult blood pressure categories (ACC/AHA categories). These are diagnostic categories, not treatment thresholds.

| Category | Systolic (mmHg) | Diastolic (mmHg) |
| --- | --- | --- |
| Normal | below 120 | and below 80 |
| Elevated | 120 to 129 | and below 80 |
| Stage 1 hypertension | 130 to 139 | or 80 to 89 |
| Stage 2 hypertension | 140 or higher | or 90 or higher |

## What abnormal values mean

- Repeatedly high readings: primary hypertension in most; look for secondary causes in young patients or resistant hypertension.
- Very high readings with symptoms of organ damage (chest pain, neurological deficit, dyspnea, visual change): hypertensive emergency.
- Hypotension: hypovolemia, sepsis, cardiogenic shock, anaphylaxis and drugs.
- Difference above 15 mmHg between arms: aortic dissection, coarctation or subclavian stenosis.
- Wide pulse pressure: aortic regurgitation, arterial stiffness of older age and hyperthyroidism; narrow: tamponade, severe aortic stenosis or shock.
- Systolic fall of more than 10 mmHg on inspiration (pulsus paradoxus): cardiac tamponade or severe asthma.

## Common errors

- Cuff too small for the arm: falsely high reading; cuff too large: falsely low reading.
- Arm hanging below the heart, unsupported back or crossed legs: higher readings.
- Deflating too fast: underestimates systolic and overestimates diastolic.
- Not estimating systolic by palpation first and missing the auscultatory gap, especially in hypertensive and older patients.
- Talking with the patient during measurement or measuring over clothing.
- Always rounding to zero or five instead of reading the exact value.

## Test yourself

Think of the answer, then tap the question to see it.

## What happens to the reading if the cuff is too small for the arm?

The pressure reads falsely high, because more cuff pressure is needed to compress the artery.

## What is the auscultatory gap and how is the error it causes avoided?

A silent interval between systolic and diastolic sounds, common in hypertensive patients; it is avoided by first estimating systolic by palpating the radial pulse and inflating above that number.

## Under the 2025 AHA/ACC guideline, how is a reading of 134/78 mmHg in an adult classified?

As stage 1 hypertension, because systolic is between 130 and 139 mmHg; only one of the two numbers needs to reach the category.

## What does a difference of more than 15 mmHg between the arms suggest?

A vascular problem, such as aortic dissection, coarctation of the aorta or subclavian artery stenosis.

## Which Korotkoff phase is used as the diastolic pressure in adults?

Phase V, when the sounds disappear completely.

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## See it in 3D

The structures of Durgical's 3D anatomy where it is found.

- [Brachial artery](https://durgical.com/en/anatomy/brachial-artery/)
- [Radial artery](https://durgical.com/en/anatomy/radial-artery/)

## Related

- [Vital signs: what they are and how to record them](https://durgical.com/en/clinical-exam/vital-signs-what-they-are-and-how-to-record-them/)
- [Orthostatic vital signs](https://durgical.com/en/clinical-exam/orthostatic-vital-signs/)
- [Hypertensive emergency: target-organ signs](https://durgical.com/en/clinical-exam/hypertensive-emergency-target-organ-signs/)
- [Abnormal pulses: paradoxus, alternans, parvus et tardus, bounding](https://durgical.com/en/clinical-exam/abnormal-pulses-paradoxus-alternans-parvus-et-tardus-bounding/)
- [Peripheral pulses and the ankle–brachial index](https://durgical.com/en/clinical-exam/peripheral-pulses-and-the-ankle-brachial-index/)

## Related conditions

- [Arterial hypertension](https://durgical.com/en/conditions/arterial-hypertension/)
- [Hypertensive emergency and urgency](https://durgical.com/en/conditions/hypertensive-emergency-and-urgency/)
- [Aortic dissection](https://durgical.com/en/conditions/aortic-dissection/)

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Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: [Blood pressure measurement: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/007490.htm) (U.S. National Library of Medicine (MedlinePlus), 2025); [Hypertension - Cardiology - MSD Manual Professional Edition](https://www.msdmanuals.com/professional/cardiovascular-disorders/hypertension/hypertension) (Merck & Co. (MSD Manual Professional Edition), 2025); [Cardiovascular Examination - Cardiology - MSD Manual Professional Edition](https://www.msdmanuals.com/professional/cardiovascular-disorders/approach-to-the-cardiac-patient/cardiovascular-examination) (Merck & Co. (MSD Manual Professional Edition), 2025).

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/clinical-exam/blood-pressure-measurement/