Fainting - Diagnosis 

Diagnosing fainting 

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In some cases of fainting it is important to see a health professional after the fainting episode, to ensure there is no underlying health condition. 

Your GP will be able to diagnose the type of fainting you have, and determine whether further treatment is needed.

When to see your GP

Most cases of fainting are not a cause for concern, and require no treatment.

But if you are concerned by your fainting episode, see your GP.

You should see your GP after you have fainted if you:

  • have no previous history of fainting
  • experience repeated episodes of fainting
  • injure yourself during a faint
  • have diabetes, which is a condition that is caused by too much glucose in the blood
  • are pregnant
  • have a history of heart disease, which is where your heart's blood supply is blocked or interrupted
  • experienced chest pains, an irregular heartbeat or a pounding heartbeat before you lost consciousness
  • experienced a loss of bladder or bowel control
  • took longer than a few minutes to regain consciousness

Assessment

During an assessment after a fainting episode, your GP will ask about the circumstances surrounding your fainting episodes and your recent medical history. They may:

  • Measure your blood pressure.
  • Listen to your heartbeat using a stethoscope.

Electrocardiogram (ECG)

If your GP suspects your fainting episode may have been caused by a problem with your heat, they may suggest an ECG.

An ECG records the rhythm and electrical activity of your heart. A number of small, sticky patches called electrodes are placed on your arms, legs and chest. Wires connect the electrodes to an ECG machine.

Every time your heart beats, it produces tiny electrical signals. The ECG machine traces these signals on paper, recording any abnormalities in your heartbeat.

An ECG is usually carried out at a hospital or GP surgery. The procedure takes about five minutes and is painless.

Carotid sinus test

If your GP suspects your fainting episode was associated with carotid sinus syndrome, they may massage your carotid sinus to see whether it makes you feel faint or lightheaded. Your carotid sinus is a collection of sensors in the carotid artery, which is the main artery in your neck that supplies blood to your brain.

If the carotid sinus massage causes symptoms, it may indicate that you have carotid sinus syndrome. See causes of fainting for more information.

Blood tests

Blood tests may be carried out to rule out conditions such as diabetes or anaemia. Anaemia is a condition where the body does not produce enough oxygen-rich red blood cells.

Tilt-table test

If your GP suspects that your fainting episode was associated with low blood pressure, they may suggest a tilt-table test.

If your GP does not have access to a tilt-table, you may be referred to a specialist, for example at a hospital, to have this test.

During the test you will be strapped to a table that is tilted upwards. If the sudden move from a horizontal to a vertical position makes you feel lightheaded, it is likely that you have orthostatic hypotension.

Alternatively, your GP may measure your blood pressure while you are lying down and again after you stand up. You may have orthostatic hypotension if your blood pressure falls after you stand up.

If you have orthostatic hypotension, you may be asked further questions to help determine the cause. For example, it can sometimes occur as a side effect of some medications.

Next steps

If tests reveal that there is an underlying cause of your fainting, such as a heart problem or orthostatic hypotension, your GP may recommend treatment.

See treatment for fainting for more information.

Page last reviewed: 07/08/2012

Next review due: 07/08/2014

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