Gastroscopy

What is a Gastroscopy?

A gastroscopy, also called an upper gastrointestinal (GI) endoscopy or oesophago-gastro-duodenoscopy (OGD), is a procedure in which a thin, flexible tube with a light and a tiny camera at its tip, called an endoscope, is passed through your mouth. It travels down your throat and food pipe into your stomach and the first part of the small intestine, called the duodenum. The camera sends clear, magnified images to a video monitor, so that your doctor can examine the lining of your upper digestive tract in detail.

A gastroscopy can be used to:

• Find the cause of digestive symptoms such as nausea, vomiting, abdominal pain, heartburn, difficulty swallowing and bleeding in the upper digestive tract
• Detect conditions such as gastro-oesophageal reflux disease (GERD), inflammation of the lining of the food pipe or stomach (oesophagitis and gastritis), stomach and duodenal ulcers, and growths such as polyps
• Detect Helicobacter pylori (H. pylori), a stomach bacterium that is a common cause of ulcers and gastritis and a known risk factor for stomach cancer
• Spot early signs of cancer of the food pipe or stomach, and of pre-cancerous changes in the stomach lining, when treatment is most effective
• Treat certain problems during the same procedure, such as stopping bleeding, removing polyps or foreign objects, or stretching a narrowed food pipe

Why You Might Need a Gastroscopy?

Your doctor may recommend a gastroscopy if you have:

• Heartburn or acid reflux that is frequent, severe or does not improve with medication
• Pain or discomfort in the upper abdomen, or persistent indigestion or bloating, especially if you are aged 50 or above
• Persistent nausea or vomiting
• Difficulty or pain when swallowing, or a feeling that food is getting stuck
• Feeling full after eating very little, or loss of appetite
• Unexplained weight loss
• Anaemia that is not explained by other causes, such as low iron levels
• Vomiting blood, or black, tarry stools, which may be a sign of bleeding in the upper digestive tract

A gastroscopy may also be recommended to follow up on a known condition or earlier test result, for example:

• To check that a stomach ulcer has healed, or to monitor changes in the lining of the food pipe such as Barrett’s oesophagus, which can develop after long-term reflux
• To monitor pre-cancerous changes in the stomach lining, such as atrophic gastritis or intestinal metaplasia
• To check for swollen veins (varices) in the food pipe or stomach in people with cirrhosis or other long-standing liver disease, including chronic hepatitis B
• After a positive result on an H. pylori breath or stool test, or when someone has been taking pain relievers such as aspirin or anti-inflammatory medicines for a long time and develops stomach symptoms

Screening without symptoms: Unlike colorectal cancer, there is currently no national screening programme in Singapore that invites everyone to have a gastroscopy. However, your doctor may suggest a screening gastroscopy if you have no symptoms but are at higher risk of stomach cancer.

This includes people with a parent, brother or sister who has had stomach cancer, people with a past H. pylori infection, atrophic gastritis or intestinal metaplasia, people with stomach polyps, and people aged 50 and above who smoke or who have other risk factors. Speak to your doctor about whether screening is suitable for you.

Please seek medical help immediately, and do not wait for a routine appointment, if you vomit blood, pass black or bloody stools, have severe or sudden abdominal pain, have food or liquids that are getting stuck, or cannot swallow your saliva, or if you feel faint and unwell with any of these symptoms.

Why This Matters in Singapore

Stomach cancer is among the top ten cancers in Singapore. Between 2017 and 2021, according to the Singapore Cancer Registry, it made up about 4% of cancers diagnosed in men and about 3% in women. It is more often found late, because early stomach cancer usually causes no symptoms, or only vague ones that are easily mistaken for gastric or “wind” problems. In 2017, close to 6 in 10 stomach cancers in Singapore were diagnosed at stage 3 or 4, when treatment is much harder. Gastroscopy is the best way to find stomach cancer and its early warning signs.

H. pylori infection is a major cause of stomach ulcers and a leading risk factor for stomach cancer. It is usually picked up in childhood, often without any symptoms, and can stay in the stomach for many years. Studies in Singapore have found that infection rates differ among our ethnic groups, and are lower among Malays than among Chinese and Indians. The infection can be treated with a course of antibiotics, and treating it can help to prevent ulcers and lower the risk of stomach cancer.

Our diets and habits also play a part. Salted, pickled, smoked and preserved foods, such as salted fish and preserved vegetables, are linked with a higher risk of stomach cancer, as are smoking and heavy drinking. Heartburn and reflux are also very common here, and long-standing reflux can damage the lining of the food pipe over time. Many people put up with these symptoms for years, take over-the-counter antacids or traditional remedies, or assume that it is simply “gastric”. If your symptoms keep coming back, last for more than a few weeks, or come with any warning signs listed above, see a doctor rather than treating yourself.

Many Singaporeans are worried that a gastroscopy will be painful or uncomfortable, and put off having one. The procedure is usually done under sedation and is short. Many people remember very little of it afterwards. 

Preparing for Your Gastroscopy?

Your stomach needs to be empty so that your doctor can see clearly and to lower the risk of food coming up while you are sedated. Our team will give you specific instructions when you make your appointment. In general:

• Fasting: Do not eat or drink for at least 6 hours before the procedure. Ask our team whether you may have small sips of plain water, and until what time. Remember that kopi, teh, milk, soup and bubble tea all count as food and drink.
• Medication: Take your regular medicines as advised by your doctor, with a small sip of water if allowed. Blood-thinning medicines such as aspirin, clopidogrel or warfarin, and certain diabetes medicines and insulin, may need to be adjusted or stopped a few days before. Do not stop any medicine unless your doctor tells you to.
• Supplements and traditional medicine: Tell your doctor about all the medicines you take, including over-the-counter pain relievers, Chinese or other traditional medicines, herbal products and supplements such as fish oil, ginkgo and ginseng, as some may increase your risk of bleeding.
• Acid-reducing medicines and H. pylori testing: Medicines that reduce stomach acid, and recent antibiotics, can affect H. pylori test results. Ask your doctor whether you should stop them before your gastroscopy.
• Medical conditions: Tell our team if you have diabetes, heart disease, lung disease, sleep apnoea, high blood pressure, kidney disease or liver disease, or if you have had previous problems with sedation or anaesthesia.
• Allergies: Tell our team about any allergies, especially to medicines, sedatives, anaesthetic spray or latex.
• Pregnancy: Tell our staff if you are pregnant or think you may be pregnant.
• Bring a companion: As you will be sedated, you will need an adult to take you home and stay with you for the rest of the day. Please arrange this beforehand, as we may not be able to proceed without one.
• What to bring: Your doctor’s referral letter, your NRIC (or passport if you are an international patient), previous endoscopy or biopsy reports, and a list of your medications.
• What to wear: Wear comfortable, loose clothing. Remove dentures, if you have any, and leave jewellery at home.
• Smoking: Do not smoke on the day of the procedure, as it can increase stomach acid and affect how you react to sedation.
• Costs and insurance: Check with your insurer whether pre-authorisation is needed, and bring your insurance details if you wish to make a claim.

What Happens During a Gastroscopy?

• The procedure is performed in our Endoscopy Suite. You will be asked to confirm your details and when you last ate or drank, and the doctor will explain the procedure and ask you to sign a consent form.
• A small tube (cannula) will be placed in a vein in your hand or arm, so that sedation can be given. Your breathing, heart rate, blood pressure and blood oxygen level will be monitored throughout the procedure.
• You will be asked to lie on your left side. A numbing (anaesthetic) spray will be applied to the back of your throat, and a small mouthguard will be placed between your teeth to protect your teeth and the scope. It does not block your breathing.
• Sedation is usually given through the cannula. Most people feel relaxed and drowsy, and many do not remember the procedure afterwards.
• Your doctor will gently pass the endoscope through your mouth and down your throat. Swallowing as instructed will help it to pass. Air is gently passed through the scope to open up the stomach so that the lining can be seen clearly, so you may feel some bloating or belching.
• The doctor examines your food pipe, stomach and the first part of your small intestine. Small tissue samples (biopsies) may be taken, including a test for H. pylori. Polyps may be removed, and bleeding can be treated through the scope.
• The scope is then withdrawn. Most of the air is removed through the scope, which helps to ease any bloating.

Are There Any Risks?

Gastroscopy is a safe procedure and serious problems are uncommon. As with any procedure, there are some risks, which your doctor will explain before you sign the consent form. They include:

• A sore throat, bloating, cramps or wind, which are common and usually settle within a day
• A reaction to the sedative or anaesthetic spray, including problems with breathing, heart rate or blood pressure, which are more likely in older people and in those with heart or lung disease
• Bleeding, which is more likely after a biopsy or removal of a polyp, and which often stops by itself or can be treated through the scope
• A tear (perforation) in the wall of the food pipe, stomach or duodenum, which is very rare but may need hospital admission, and sometimes surgery
• Damage to teeth, crowns or dental work, which is uncommon

What Happens After a Gastroscopy?

• You will be taken to a recovery area to rest, and your vital signs will be closely monitored until the effects of the sedation wear off. This usually takes about an hour.
• You may have a sore throat, bloating, cramps or belching for a short while. These should improve with time. Throat lozenges and walking around can help.
• Do not eat or drink until the numbness in your throat has worn off, usually after about an hour. Start with sips of water, then a light meal, and go back to your normal diet if you feel well. If a biopsy was taken or a polyp removed, your doctor may give you specific advice on diet.
• Sedation can affect your judgement and reactions for the rest of the day. Do not drive, ride or operate machinery, drink alcohol, make important decisions or sign legal documents for 24 hours. Have an adult take you home and stay with you.
• Your doctor will tell you what was seen. As the sedation may cause you to forget what you were told, it is helpful for your companion to listen too. You will be given a written report.
• If biopsies were taken, the results usually take several days to a week. You will be given a follow-up appointment to go through your results. Depending on the findings, your doctor will prescribe the appropriate treatment.

Understanding Your Results

Your doctor will consider what was seen during the procedure together with any biopsy results, your symptoms and your medical history.

• Normal findings: No ulcers, inflammation or growths were seen. This is reassuring. If you still have symptoms, your doctor may look for other causes, such as functional dyspepsia (indigestion without a structural cause), or problems in other parts of the digestive system.
• Gastritis or oesophagitis: Redness or inflammation of the lining of the stomach or food pipe. This may be caused by acid reflux, H. pylori, medicines such as aspirin or anti-inflammatory pain relievers, alcohol or other causes. Treatment depends on the cause and often includes medicine to reduce stomach acid.
• Ulcers: Open sores in the lining of the stomach or duodenum. They are most often caused by H. pylori or by anti-inflammatory medicines. Treatment usually includes acid-reducing medicine, and antibiotics if H. pylori is found. Stomach ulcers may be biopsied or checked again with a repeat gastroscopy to make sure that they heal.
• H. pylori infection: If H. pylori is found, you will usually be given a course of antibiotics and acid-reducing medicine for about two weeks. It is important to complete the full course. A follow-up test is usually done a few weeks after treatment to confirm that the infection has cleared.
• Reflux and Barrett’s oesophagus: Signs of acid reflux, such as inflammation at the lower end of the food pipe, may be seen. In some people, long-standing reflux changes the lining of the food pipe (Barrett’s oesophagus), and your doctor may recommend regular check-ups.
• Polyps: Most polyps in the stomach are harmless, but some can turn cancerous over time. Your doctor may remove or biopsy them.
• Pre-cancerous changes: Biopsies may show atrophic gastritis or intestinal metaplasia, which are changes in the stomach lining that can raise the risk of stomach cancer. Most people with these changes do not develop cancer, but your doctor may recommend follow-up gastroscopies at regular intervals.
• Cancer: If a growth or suspicious area is found, biopsies will confirm the diagnosis. Your doctor will explain the results and refer you to a specialist for further tests and treatment. The earlier a cancer is found, the more treatment options are available.

Looking After Your Digestive Health

• See a doctor if you have heartburn, indigestion or stomach pain that keeps coming back, or any warning signs such as weight loss, trouble swallowing, vomiting or black stools
• Ask your doctor about testing and treatment for H. pylori if you have a family history of stomach cancer or a history of ulcers
• Cut down on salted, pickled, smoked and preserved foods such as salted fish and preserved vegetables, and limit charred and heavily processed meats
• Eat more fresh fruit and vegetables, and choose a balanced diet
• Do not smoke, and limit alcohol, as both irritate the stomach lining and increase the risk of stomach and food pipe cancer
• Avoid taking aspirin and anti-inflammatory pain relievers regularly without medical advice. Take them with food and ask your doctor or pharmacist about safer options if you need them for a long time
• If you have reflux, eat smaller meals, avoid lying down for two to three hours after eating, and avoid heavy late-night suppers. Raising the head of your bed and losing excess weight can also help
• Keep to a healthy weight and stay physically active
• If you have chronic hepatitis B or liver disease, keep to your regular follow-up appointments, as your doctor may advise a gastroscopy to check for swollen veins in the food pipe

Should you feel unwell after the scope, contact your doctor immediately or call our 24-Hour Medical Urgency Clinic.