Common Questions About Gastroscopy

Gastroscopy is a procedure used to investigate problems in the upper part of the digestive system, including the oesophagus, stomach and small intestine. Understandably, many patients feel uncertain before their test, especially if it’s their first time.

We spoke to Professor Lee Dvorkin, Consultant Laposcopic and General Surgeon at St John & St Elizabeth Hospital to create a guide to common questions about gastroscopy. Professor Dvorkin’s clinical practice includes the investigation and management of gastrointestinal problems, such as irritable bowel syndrome (IBS), inflammatory bowel disease, diverticular disease, abdominal pain and all common anal conditions.

This page brings together answers to the most common questions about gastroscopy, covering everything from how to prepare and what happens during the procedure, to when and how you’ll receive your biopsy results. Whether you’re visiting our endoscopy unit for a routine check or to investigate specific symptoms, we’re here to help you feel informed and at ease.

What is a Gastroscopy?

A gastroscopy is a type of endoscopy procedure that allows a doctor to examine the inside of your oesophagus, stomach and the first part of your small bowel (the duodenum). It uses a thin, flexible tube known as a gastroscope, which has a tiny camera and light at the tip. This small tube is gently passed through your mouth and down into your stomach, allowing the doctor to check for inflammation, ulcers, or other issues that may be causing symptoms like pain, heartburn, or difficulty swallowing.

You may also hear this test referred to as an ‘upper endoscopy’. It is carried out in our endoscopy unit and typically takes less than 15 minutes. The procedure is often performed with a local anaesthetic spray to numb the throat, and in some cases, a sedative is given to help you feel relaxed. During the test, your consultant may take a small tissue sample (biopsy) for further analysis. This is painless and helps us understand more about your health.

Why You Might Need a Gastroscopy

A gastroscopy is used to investigate symptoms affecting your throat, stomach or small intestine. Some of the most common reasons patients are referred for a gastroscopy include:

• Persistent indigestion or heartburn
• Difficulty swallowing (dysphagia)
• Unexplained weight loss
• Ongoing nausea or vomiting
• Suspected stomach ulcers
• Anaemia linked to blood loss
• Checking for inflammation, infection or bleeding
• Monitoring known conditions such as Barrett’s oesophagus

The procedure may also be used to take tissue samples (biopsies) or to treat certain problems directly. Your consultant will discuss your medical history before the test and explain why a gastroscopy has been recommended in your case.

Preparing for Your Gastroscopy

To get the most accurate results from your gastroscopy, your stomach must be empty during the procedure. This means you’ll need to stop eating six hours before your appointment, and avoid drinking for at least two hours beforehand, only small sips of water may be allowed. If you’re unsure, please contact us or check the information leaflet provided at your clinic appointment.

• You should continue taking medicines as normal unless you’ve been advised to stop taking certain ones (such as those for diabetes or blood thinning). Your consultant or nurse will let you know what’s safe to take, especially if you have conditions like diabetes or heart problems.
• You might be offered a local anaesthetic spray (also called throat spray) to numb the throat, or a mild sedative to help you feel relaxed during the test. The endoscopy staff will discuss these options with you in advance and answer any questions you may have.
• Before the procedure, you will be asked to sign a consent form to confirm that you understand what’s involved. You should also bring any important documents and a list of your current medications. If you wear false teeth, you may be asked to remove them just before the test.
• If you have also been given bowel preparation for a different endoscopy procedure, such as a flexible sigmoidoscopy or colonoscopy, please follow the separate instructions given for that specific test.

What to Expect During a Gastroscopy

When you arrive at the endoscopy unit, a nurse will greet you and check your medical history, blood pressure, and any relevant information from your clinic appointment. You will be given time to ask questions, and the endoscopist explains everything again before the test begins.

The procedure itself takes place in a dedicated endoscopy room. You will lie on your left side, and a local anaesthetic throat spray will be used to numb the back of your mouth. A sedative can also be given through a small tube (cannula) in your arm if you wish, to help you feel relaxed, but this means you will need someone to accompany you home.

The doctor gently passes a small, flexible tube through your mouth and down into your stomach. This tube contains a tiny camera which sends images to a screen, allowing the doctor to examine your upper digestive system. Air is passed into the stomach to provide a clear view, which may make you feel bloated or cause some mild discomfort. If necessary, a tissue sample (biopsy) may be taken using small instruments through the tube.

Most patients find the test uncomfortable rather than painful. The whole procedure usually takes just a few minutes.

After the Gastroscopy

After the test, you will be taken to a recovery area within the endoscopy unit, where the nursing team will monitor you for a short period, usually around 30 minutes to a few hours, depending on whether you had sedation. Most patients feel well enough to go home soon after, though it is normal to have a slightly sore throat or feel bloated due to the air used during the procedure.

If you had a sedative, you won’t be able to drive or operate machinery for at least 24 hours, and you will need a family member or friend to take you home and stay with you for a short while. If you were awake during the procedure, you’ll likely be able to resume normal activities more quickly.

The endoscopist explains any initial findings before you leave, and if a biopsy or tissue sample was taken, your consultant will discuss the biopsy results with you at a later clinic appointment or by phone. If you have questions, feel uncertain, or develop new symptoms afterwards, please contact our endoscopy department directly.

Are There Any Risks with a Gastroscopy?

Gastroscopy is generally considered a safe procedure, but like all medical tests, there are a few risks to be aware of. These are rare, and your doctor or nurse will discuss them with you beforehand, as part of the consent form process.

Some possible risks include:

• Sore throat – common and usually mild, lasting a day or two
• Bleeding – particularly if a biopsy or treatment is performed
• Infection – uncommon, but may require treatment if it occurs
• Reaction to the sedation – including drowsiness or feeling hot or dizzy
• Damage to teeth – very rare, but possible if your mouthguard slips
• Chest infection – an unusual but potential complication if you have pre-existing health issues
• Tear or hole (perforation) of the food pipe – extremely rare, but may require further treatment

If you have underlying health conditions, such as heart problems, diabetes, or are taking medicines that affect blood clotting, it is important to discuss these in advance with your medical team. The staff in our endoscopy units are trained to manage complications if they occur and your safety is always our priority.

How to Find Us for a Private Gastroscopy in London

St John & St Elizabeth Hospital is located in St John’s Wood (NW8), a well-connected and trusted destination for private endoscopy procedures in London. Our hospital is easily accessible from surrounding areas including Hampstead (NW3) and Kilburn (NW6), making it convenient for patients across North West London.

More About Endoscopy at St John & St Elizabeth Hospital

Choosing St John & St Elizabeth Hospital for your gastroscopy means receiving expert care in a calm, supportive setting. Our endoscopy units are equipped with modern technology and staffed by highly trained consultants, nurses, and endoscopy staff who prioritise patient comfort and safety at every stage of the procedure.

We offer:

• Prompt appointments – reducing the wait for both your test and any follow-up treatment
• Expert consultants – experienced in diagnosing and treating a wide range of conditions affecting the throat, stomach, and small bowel
• Sedation and comfort options – including local anaesthetic spray to the throat or intravenous sedative, so you can choose what suits you best
• On-site support services – including pharmacy, imaging, and same-day diagnostic tests where needed

From the moment you arrive in our waiting area to the time you leave the recovery area, our team is there to help you feel relaxed, answer your questions, and make the process as smooth as possible. If you need to contact us before your appointment, for example, to discuss medicines you are taking or to confirm arrival details, our team will be happy to assist.

Additional Questions

Is gastroscopy used before bariatric surgery?

Yes. An upper endoscopy procedure is sometimes carried out before bariatric surgery to check the oesophagus, stomach, and small intestine for any problems that could affect your treatment. It can help identify ulcers, inflammation, or other conditions that may need attention before surgery.

How is gastroscopy different from a colonoscopy?

A gastroscopy examines the upper digestive system, the oesophagus, stomach, and small bowel, using a small flexible tube with a tiny camera. A colonoscopy looks at the large bowel (colon) and rectum, often requiring bowel preparation beforehand.

What’s the difference between an endoscopy and a gastroscopy?

“Endoscopy” is a general term for procedures using a flexible tube to examine inside the body. “Gastroscopy” is a type of endoscopy focused on the upper digestive tract.

What should I eat after the procedure?

If you’ve had a local anaesthetic spray, wait until the numbness wears off before eating or drinking, usually around 30 to 60 minutes. Start with small sips of cool water, then soft foods like yoghurt or soup. Avoid hot drinks until your throat feels normal again. If sedation was used, follow the advice given by your nurse.