How is an abscess diagnosed?

What is an abscess?

An abscess is a collection of pus caused by an infection. It can form in the skin, gums, teeth, or deeper inside the body.

Common signs include swelling, pain, redness, warmth, and sometimes a raised lump. Some abscesses may also cause fever or make you feel generally unwell.

How a GP diagnoses an abscess

A GP will usually start by asking about your symptoms and how long they have been present. They may also ask whether you have had any injury, skin condition, or dental problem that could have led to the infection.

The next step is often a physical examination. A GP will look at the area, check for tenderness, heat, swelling, and any discharge, and may gently feel the lump to assess it.

What the doctor looks for

Doctors often look for a soft centre, which can suggest pus has collected under the skin. They may also check whether the skin around it is red or inflamed.

If the abscess is near the mouth, gums, or teeth, a dentist may examine it more closely. Tooth abscesses often cause pain when biting, sensitivity to hot or cold, and swelling in the face or jaw.

Tests that may be needed

Many abscesses can be diagnosed from the symptoms and examination alone. However, if the abscess is deep, unusual, or not clearly visible, more tests may be needed.

An ultrasound scan can help confirm whether there is a pocket of fluid under the skin. In some cases, blood tests may be taken to look for signs of infection or inflammation.

Diagnosing abscesses inside the body

Abscesses deeper inside the body, such as in the abdomen or around internal organs, are harder to diagnose. Symptoms may include fever, pain, fatigue, or feeling very unwell without an obvious cause.

Doctors may use imaging tests such as a CT scan or MRI to find the abscess. These scans help show where the infection is and whether it has spread.

When to seek urgent medical help

You should seek medical advice promptly if you think you have an abscess, especially if the area is getting bigger or more painful. This is important if you have a weakened immune system, diabetes, or a fever.

Get urgent help if the swelling is on the face, near the eye, or making it hard to breathe, swallow, or open your mouth. These can be signs of a more serious infection that needs quick treatment.