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What Is Gastroscopy? 4 Key Facts About Gastroscopy Procedure [2023]

Dr QM Leong
Dr QM Leong

Gastroscopy, or upper gastrointestinal endoscopy or upper GI endoscopy, is a widely-used diagnostic procedure to examine the upper part of the gastrointestinal (GI) tract.

We’ll discuss the gastroscopy procedure, its applications, and how to prepare for it.

1. What Can A Gastroscopy Detect?

A gastroscopy can detect various issues within the upper GI tract, including the oesophagus (food pipe), stomach, and the first part of the small intestine (duodenum). Common medical conditions that can be diagnosed through this procedure include:


Gastritis is an inflammation of the stomach caused by various factors. Gastroscopy allows for direct visualisation of the stomach lining.

The doctor can identify signs of inflammation or irritation like redness, swelling, or erosions during the procedure. In some cases, they may also observe changes in the stomach’s mucosal pattern or the presence of ulcers.

Gastric Cancer

Gastroscopy is vital in diagnosing gastric cancer in its early stages, as it allows doctors to inspect the stomach wall and obtain tissue samples for biopsy.

Gastroesophageal Reflux Disease (GERD)

Gastroscopy helps determine the extent of damage caused by stomach acid reflux, a key contributor to GERD.

Peptic Ulcers

These painful sores can develop in the stomach or small intestine due to excessive stomach acid production or bacterial infection. Gastroscopy is crucial in identifying their presence and severity.

Celiac Disease

A gastroscopy can confirm or rule out this autoimmune disorder by examining the small bowel and collecting tissue samples.

Strictures Or Narrowing Of The Food Pipe

Gastroscopy can detect strictures, which may cause difficulty swallowing, and help identify the underlying cause.

Inflammation Or Swelling In The Upper GI Tract

Gastroscopy effectively diagnoses conditions like esophagitis, gastritis, and duodenitis, which involve inflammation of the oesophagus, stomach, or duodenum, respectively.

2. What To Expect During A Gastroscopy Procedure?

What To Expect During A Gastroscopy Procedure?

A gastroscopy is typically performed as an outpatient procedure, which means patients can return home the same day. The process involves several steps to ensure patient comfort and accurate diagnosis.

Here’s what to expect during a gastroscopy procedure:

Step 1: Consultation

Before the gastroscopy, the doctor will review the patient’s medical history, discuss any ongoing medical conditions, and address any concerns or questions the patient might have. This is also the time to inform the doctor about any allergies or medications the patient is taking.

Step 2: Sedation And Anaesthesia

To ensure patient comfort during the procedure, a sedative is usually administered intravenously to help them relax. Some patients may also receive a local anaesthetic spray to numb the throat, minimising the gag reflex and making it easier to insert the endoscope.

Patients may feel drowsy or have difficulty breathing due to the sedation, but this is generally well-controlled by the medical staff.

The sedation will wear off gradually after the procedure, but patients should still avoid operating heavy machinery or making important decisions for at least 24 hours.

Step 3: Insertion Of The Endoscope

Once the patient is relaxed and their throat is numbed, the doctor will gently insert a thin, flexible tube called an endoscope through the patient’s mouth and down the food pipe (oesophagus). 

The endoscope has a light and a camera at its tip, enabling the doctor to examine the upper GI tract in detail.

Step 4: Inspection And Tissue Samples

The endoscope transmits real-time images to a monitor, allowing the doctor to closely inspect the oesophagus, stomach, and the first part of the small intestine (duodenum).

The doctor will look for abnormalities like inflammation, ulcers, or strictures. The doctor may take tissue samples using small instruments passed through the endoscope for further analysis if needed. These samples can help diagnose gastritis, celiac disease, or gastric cancer.

Step 5: Additional Procedures

Sometimes, the doctor may perform additional procedures during the gastroscopy to address specific issues. This can include removing polyps, dilating strictures, treating bleeding ulcers, or placing stents to open a narrowed area.

Step 6: Removal Of The Endoscope

Once the examination is complete, the doctor will carefully remove the endoscope, ensuring the patient’s comfort throughout the process.

Step 7: Recovery

After the procedure, patients are monitored in a recovery area until the sedative wears off. Depending on the patient’s reaction to the sedative, this can take anywhere from 30 minutes to a few hours.

They may experience a mild sore throat or bloating, which typically subsides within a few hours.

Having someone accompany the patient to drive them home is essential, as they may still feel tired from the sedative.

Step 8: Post-Procedure Care And Follow-Up

The doctor will discuss the results of the gastroscopy with the patient and provide any necessary recommendations for further tests, treatment, or lifestyle changes.

Patients may experience some mild discomfort like sore throat or bloating, but these usually resolve on their own after a few hours or a day.

If the doctor took tissue samples, the results may take a few days to be processed, and the doctor will schedule a follow-up appointment to discuss the findings.

3. How To Prepare For Gastroscopy

How To Prepare For Gastroscopy

Proper preparation is essential for a successful gastroscopy. Here’s how patients can get ready for the procedure:


To ensure a successful gastroscopy, patients must have an empty stomach. This allows the doctor to have a clear view of the upper GI tract and minimises the risk of complications, such as aspiration of stomach contents into the lungs.

Patients should follow a low-residue diet or refrain from eating or drinking for at least 6-8 hours before the procedure. This means no solid foods, liquids, or even gum.

Water may be allowed in small amounts up to two hours before the procedure, but patients should follow their doctor’s instructions.

Adjust Your Medication

Patients should provide their doctor with a complete list of medications they are taking, including prescription drugs, over-the-counter medicines, vitamins, and supplements.

Some medications, such as blood thinners or nonsteroidal anti-inflammatory drugs (NSAIDs), may need to be adjusted or stopped temporarily before the gastroscopy.

This is because they can increase the risk of bleeding, especially if the doctor needs to take a biopsy or perform a therapeutic intervention during the procedure.

Patients should follow their doctor’s instructions regarding medication adjustments.

Don’t Engage In Strenuous Activities

On the day of the gastroscopy, patients should avoid engaging in strenuous activities or anything that may cause discomfort or stress.

They should arrange for a close friend or family member to accompany them to the procedure and drive them home afterwards, as they may feel tired and unable to drive safely due to the sedation administered during the procedure.

4. Is A Gastroscopy Safe?

Gastroscopy is typically a very safe procedure and is valuable in diagnosing gastrointestinal issues like stomach ulcers, inflammation, or tumours.

However, as with any medical procedure, there is a small risk of complications, such as bleeding, infection, or perforation of the gastrointestinal tract. 

Patients should be aware of these risks and discuss them with their doctor to make an informed decision about undergoing the procedure.

Conclusion On What Is Gastroscopy

A gastroscopy or gastrointestinal endoscopy is an essential diagnostic tool for examining the upper gastrointestinal tract. Proper preparation, including fasting and medication adjustments, can help minimise the risk of serious complications and ensure a successful procedure.

If you are experiencing gastrointestinal issues or require colorectal surgery, schedule a consultation with Dr QM Leong. 

As a specialist in colorectal surgery in Singapore, he is highly experienced in diagnosing and treating a wide range of colorectal and gastrointestinal cancers.

His other areas of expertise include cyst removal, gallstone removal, hernia surgery, colonoscopy, and more.

You may also visit his clinic at the following address:

820 Thomson Road, Mount Alvernia Hospital Medical Centre A 
#01-06, Singapore 574623

Frequently Asked Questions About What Is Gastroscopy

No, gastroscopy is generally not painful, as patients are typically sedated or given local anaesthesia to minimise discomfort during the procedure. They may feel a slight gagging sensation or pressure when the endoscope is inserted, but the sedation helps to keep them relaxed.

Endoscopy is a broad term to describe a range of procedures that involve inserting a flexible tube with a light and camera into the body to examine internal organs. Gastroscopy is a type of endoscopy specifically focused on examining the upper gastrointestinal tract, including the oesophagus, stomach, and the first part of the small intestine (duodenum).

Side effects of gastroscopy are generally mild and temporary. These may include a sore throat, bloating, or mild abdominal discomfort. More serious complications, such as bleeding, infection, or perforation of the gastrointestinal tract, are rare but can occur.

Preliminary gastroscopy results are often available immediately after the procedure, as the doctor can observe the upper gastrointestinal tract directly during the examination. However, if a biopsy is taken, it may take several days to a week for the results to be analysed and returned.

Patients should avoid alcohol, caffeine, and spicy or acidic foods until they have fully recovered and feel comfortable eating them.

Gastroscopy is used to examine the upper GI tract, including:

  • Oesophagus
  • Stomach
  • Duodenum (first part of the small intestine)

A gastroscopy examines the upper gastrointestinal tract (oesophagus, stomach, and duodenum), while a colonoscopy focuses on the lower gastrointestinal tract, specifically the colon and rectum. Both procedures involve inserting a flexible tube with a light and camera into the body, but the gastroscopy uses the mouth as the entry point, while the colonoscopy uses the rectum.

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