A gastroscopy is a very safe procedure and the risks of serious complications are small.

A gastroscopy that is being used to diagnose a condition (diagnostic gastroscopy) has a 1 in 1,000 chance of causing a serious complication.

Because of its more invasive nature, a gastroscopy that is being used to treat a condition (therapeutic gastroscopy) has a higher risk. But this is still relatively small, at around 1 in 100.

Possible complications include:

• adverse effects from sedation
• infection
• bleeding
• perforation (tearing)

Sedation

Sedation is usually a safe procedure, but it can occasionally cause complications which can include:

• feeling or being sick
• a burning sensation at the site of the injection
• small particles of food falling into the lungs and triggering an infection (aspiration pneumonia)
• irregular heartbeat
• breathing difficulties

Very rarely, the complications arising from sedation can result in stroke, although this is extremely unlikely, occurring in 1 out of 25,000 cases.

Infection

Occasionally, during a gastroscopy bacteria can enter the bloodstream through small tears and cuts in body tissue that were formed during the procedure. In most cases, the bacteria do not cause serious problems and are killed by the immune system.

However, in rare cases, the bacteria can travel to the heart and infect the lining, muscles and valves of the heart. This type of infection is known as endocarditis.

Symptoms of endocarditis include:

• high temperature (fever) of 38°C (100.4°F) or above
• chills
• an unusual sounding heartbeat (murmur)
• fatigue
• night sweats
• aching joints and muscles

Endocarditis can usually be treated with injections of antibiotics.

Read more about the treatment of endocarditis.

Bleeding

Sometimes, the endoscope can accidentally damage a blood vessel, causing it to bleed.

The source of bleeding can usually be repaired using a further gastroscopy, in the same way that bleeding varices or an ulcer is repaired. Blood transfusions may also be required to replace lost blood.

Perforation

During a gastroscopy, there is a small risk of the endoscope tearing the tissue inside your oesophagus, abdomen or chest.

The warning symptoms include:

• neck pain
• pain when swallowing
• abdomen pain
• high temperature
• breathing difficulties

If the perforation is not severe, it can normally be left to heal by itself. You may be given antibiotics to prevent an infection occurring at the site of the tear.

If the perforation is more serious (indicated by severe pain that does not respond to painkillers), then surgery may be needed to repair it.