Gastroscopy (OGD)

What is gastroscopy (OGD)? 

Gastroscopy, also known as oesophago-gastro-duodenoscopy (OGD), is a medical procedure that allows doctors to examine the lining of the upper part of the digestive system. This includes the oesophagus (food pipe), stomach, and duodenum (the first part of the small intestine). It is carried out using a thin, flexible tube called an endoscope, which has a light and camera at its tip. The endoscope is gently passed through the mouth and guided down into the digestive tract, transmitting detailed images to a monitor so that the doctor can identify abnormalities with precision.

Gastroscopy is commonly used to investigate symptoms such as persistent heartburn, difficulty swallowing, unexplained abdominal pain, indigestion, or bleeding. It also helps diagnose conditions like gastritis, ulcers, coeliac disease, and early signs of cancer. In addition to diagnosis, the procedure can be therapeutic; for example, doctors may remove polyps, take tissue biopsies, stop bleeding, or widen narrowed areas of the oesophagus. As a minimally invasive test, gastroscopy is usually safe and well tolerated. 

Why is a gastroscopy (OGD) performed? 

Gastroscopy is a key investigation for identifying and sometimes treating a wide range of conditions affecting the upper digestive tract. It is often recommended when symptoms persist despite initial treatment, or when there is a need to confirm a diagnosis with direct visual evidence or tissue sampling. Because it allows doctors to see the lining of the oesophagus, stomach, and duodenum in real time, it plays a vital role in detecting early disease and guiding targeted care.

Common reasons for having a gastroscopy include:

• Persistent indigestion or heartburn — to investigate symptoms of gastro-oesophageal reflux disease (GORD) or irritation of the stomach lining, especially if symptoms do not improve with medication.

• Difficulty swallowing (dysphagia) — to assess whether narrowing, inflammation, or abnormal growths are making it harder to swallow food or liquids.

• Unexplained symptoms — such as ongoing pain, bloating, nausea, vomiting, or early satiety that could point to gastritis, ulcers, or structural abnormalities.

• Suspected bleeding — including vomiting blood (haematemesis), passing black, tarry stools (melaena), or unexplained anaemia, which may indicate an ulcer or bleeding lesion.

• Diagnosis of conditions — like peptic ulcers, gastritis, coeliac disease, Barrett’s oesophagus, or early cancers of the stomach and oesophagus.

• Therapeutic purposes — a gastroscopy is not just diagnostic. It may also be used to stop active bleeding (e.g. from ulcers or varices), remove polyps, retrieve swallowed foreign bodies, or stretch narrowed areas of the oesophagus (dilatation).

• Monitoring known conditions — to track the progression or healing of known problems, such as checking for recurrence of ulcers or assessing response to treatment in Barrett’s oesophagus.

Because it allows both diagnosis and treatment in a single session, gastroscopy is a powerful and efficient tool in managing gastrointestinal health. When performed early, it can help prevent complications and significantly improve patient outcomes.

How to prepare for a gastroscopy (OGD)? 

Proper preparation is important to ensure the test is safe and accurate. Your doctor or nurse will give you clear instructions in advance, but the following are the usual steps:

• Fasting — you will usually be asked not to eat or drink for around 6 hours before the procedure so that the stomach is empty.

• Medication adjustments — inform your doctor about all medicines you are taking, especially blood thinners, diabetes medication, or heart medicines, as you may need special instructions.

• Allergies and health conditions — let your healthcare team know if you have any allergies, breathing problems, or other medical issues.

• Sedation planning — if you are having sedation, you should arrange for someone to accompany you and take you home afterwards, as you should not drive or operate machinery for 24 hours.

• Clothing and personal items — wear comfortable clothes and avoid bringing valuables, as you will be asked to remove dentures, glasses, or jewellery before the test.

Following these steps helps ensure the procedure goes smoothly and reduces the risk of complications.

What happens during a gastroscopy (OGD)? 

A gastroscopy is typically carried out as a day procedure, meaning there is no need for an overnight hospital stay. The procedure itself usually takes between 10 and 20 minutes, though this can vary slightly depending on whether additional treatment is required at the time. 

• Throat preparation — to begin, your throat will be sprayed with a local anaesthetic to reduce sensation and suppress the gag reflex. If you are feeling anxious or uncomfortable, a mild sedative may be administered through a vein in your arm to help you relax, though you will remain conscious throughout.

• Mouth guard placement — a small plastic mouthpiece is placed gently between your teeth. This helps protect both your teeth and the endoscope during the procedure.

• Insertion of the endoscope — the doctor will then carefully guide a thin, flexible tube called an endoscope through your mouth and down the oesophagus, into the stomach, and finally into the duodenum. The tube is lubricated and manoeuvred slowly to minimise discomfort.

• Examination — the endoscope is equipped with a high-definition camera that sends real-time images to a monitor, which allows the doctor to thoroughly inspect the lining of your upper digestive tract for any signs of inflammation, ulcers, growths, or other abnormalities.

• Biopsies or treatment — if necessary, the doctor can take small tissue samples (biopsies) using instruments passed through the endoscope. These are painless and often used to test for infections such as Helicobacter pylori, check for coeliac disease, or assess suspicious areas. In some cases, treatment such as stopping bleeding, removing polyps, or dilating strictures can also be done during the same procedure.

• Completion — once the examination is complete, the endoscope is gently withdrawn. If you were given sedation, you will be taken to a recovery area where the medical team will monitor you until the effects wear off.

Most patients tolerate the procedure well, with only minor side effects such as a mild sore throat, burping, or a bloated sensation due to air introduced during the examination. These symptoms typically resolve within a few hours.

The doctor may discuss preliminary findings with you shortly after the procedure, and you will receive more detailed results, especially if biopsies were taken, at a follow-up appointment or via your referring doctor.

Are there any risks of Gastroscopy (OGD)? 

Gastroscopy is generally a safe procedure, but like any medical test, there are some risks. Serious complications are rare, and your doctor will explain these before the test.

Possible risks include:

• Sore throat or bloating — common and usually settle within a day or two.

• Reaction to sedation — mild drowsiness or dizziness may occur; you will be monitored until safe to go home.

• Bleeding — may happen if a biopsy is taken or a polyp is removed, though it is usually minor and stops on its own.

• Perforation (tear in the lining) — very rare, but may require surgery to repair.

• Infection — extremely uncommon, as equipment is thoroughly cleaned and sterilised.

Our healthcare team will take every precaution to minimise these risks, and the benefits of early diagnosis and treatment usually far outweigh the small chance of complications.

What are the benefits of Gastroscopy (OGD)?

Gastroscopy offers both diagnostic and therapeutic advantages, making it one of the most valuable tools in gastroenterology.

The main benefits include:

• Accurate diagnosis — provides a clear, direct view of the oesophagus, stomach, and duodenum to detect problems early.

• Targeted treatment — allows doctors to treat issues such as bleeding, narrowing, or polyp removal during the same procedure.

• Tissue sampling — enables biopsies to check for infections, coeliac disease, or early cancers without the need for surgery.

• Minimally invasive — offers detailed results without major surgery, with quick recovery and minimal discomfort.

• Prevention of complications — early detection and treatment can prevent serious problems like ulcers, strictures, or cancer progression.

By combining diagnosis and treatment in a single procedure, gastroscopy helps patients receive timely, effective care with lasting benefits for digestive health.

What to expect after a Gastroscopy (OGD)? 

Most people recover quickly following a gastroscopy, particularly if no sedation was used. The procedure is typically performed as a day case, so you will be monitored for a short time after the test and allowed to go home once you are stable. Your recovery experience may vary depending on whether you received sedation and whether any interventions (such as biopsies or treatments) were performed during the procedure.

After the procedure:

• Throat discomfort — it is common to have a mild sore throat, hoarseness, or a dry cough for a day or two due to the endoscope passing through the throat. You may also feel slightly bloated from the air introduced during the examination.

• Effects of sedation — if you were given a sedative, you might feel drowsy or light-headed for several hours afterwards. For safety, you should not drive, operate heavy machinery, return to work, or make important decisions (including signing legal documents) for at least 24 hours.

• Eating and drinking — you can typically resume eating and drinking once the numbness in your throat has worn off, usually after 30 to 60 minutes. Start with light meals and avoid hot drinks initially, especially if your throat is sore.

• Results discussion — the doctor may give you an overview of the findings immediately after the procedure. If biopsies were taken, these will be sent to a laboratory and the results may take several days. Your referring doctor or the specialist will follow up with a detailed explanation and further recommendations if needed..

• Return to normal activities — most patients are able to return to their usual daily activities the following day, provided they feel well. If no sedation was given, recovery is usually even quicker.

When to seek medical advice:

Although complications are rare, it is important to contact your doctor or seek medical help if you experience any of the following after the procedure:

• Severe or persistent abdominal pain
• Vomiting (especially if it contains blood)
• High fever or chills
• Difficulty breathing
• Bleeding from the mouth or black, tarry stools

Being aware of what to expect helps reduce anxiety and ensures a smoother recovery process. Our healthcare team will provide personalised aftercare instructions based on your individual needs and the findings from your procedure.

Summary 

Gastroscopy, or oesophago-gastro-duodenoscopy (OGD), is a highly valuable diagnostic and therapeutic procedure that allows direct visual assessment of the upper digestive tract. Using a slender, flexible camera, doctors can examine the oesophagus, stomach, and duodenum in detail, which helps identify the cause of persistent symptoms such as heartburn, nausea, swallowing difficulties, or unexplained weight loss. It is commonly used to diagnose a wide range of conditions, including acid reflux disease, peptic ulcers, gastritis, coeliac disease, and early-stage cancers, offering clarity when other tests remain inconclusive.

What sets gastroscopy apart is that it not only helps to detect problems early, but also allows immediate treatment during the same procedure. Biopsies can be taken painlessly, bleeding can be controlled, polyps can be removed, and narrowed areas of the digestive tract can be gently widened, all without the need for open surgery. The procedure is generally safe, well-tolerated, and performed as a day case, with most patients resuming normal activities soon after.

If you are experiencing persistent indigestion, difficulty swallowing, unexplained abdominal pain, or any other worrying digestive symptoms, schedule a consultation with Tan Siong San Surgery for a thorough evaluation and comprehensive care.

Frequently Asked Questions (FAQs)