Clinical exam · General exam and vital signs

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 · 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.

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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 (U.S. National Library of Medicine (MedlinePlus), 2025); Hypertension - Cardiology - MSD Manual Professional Edition (Merck & Co. (MSD Manual Professional Edition), 2025); Cardiovascular Examination - Cardiology - MSD Manual Professional Edition (Merck & Co. (MSD Manual Professional Edition), 2025).

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