The Ultimate Guide to Gastroscopy

A comprehensive, specialist-led guide to understanding upper GI investigation—from preparation and comfort options to expert diagnostics for reflux, GORD, and stomach pain in Christchurch.


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Expert Upper GI Investigation

If your doctor has recommended a gastroscopy, you likely have questions about what the procedure involves and why it is necessary. Gastroscopy is one of the most commonly performed and effective diagnostic tools in modern gastroenterology.

This guide, authored by Dr Jimmy Tiong and co-authored by Dr Bernard Teo, provides a thorough, evidence-based understanding of the procedure—from the clinical reasons it is recommended through to what you can expect during and after the examination.


What is a Gastroscopy?

A gastroscopy (also known as an upper gastrointestinal endoscopy or OGD) allows a specialist to examine the lining of your upper digestive tract. This includes the oesophagus (food pipe), stomach, and duodenum (the first part of your small bowel). The procedure is carried out using a gastroscope—a thin, flexible tube about the thickness of a finger, fitted with a small high-definition camera and light at the tip. As the gastroscope is gently passed through the mouth, images are displayed on a monitor in real time, giving Dr Tiong a clear, detailed view of the tissue lining that imaging like X-rays or CT scans might miss.

Why a Gastroscopy is Recommended

A gastroscopy is much more than just a visual check; it is a powerful tool for both diagnosis and immediate treatment of upper digestive issues.


Investigating Persistent Symptoms

(H3) Dr Tiong may recommend a gastroscopy to find the underlying cause of several common symptoms, including:


  • Chronic Heartburn or Reflux: Investigating GORD (Gastro-oesophageal reflux disease).
  • Dysphagia: Difficulty or pain when swallowing.
  • Persistent Nausea: Or unexplained vomiting.
  • Abdominal Pain: Specifically in the upper abdomen or "pit" of the stomach.
  • Unexplained Weight Loss: Or signs of internal bleeding (anæmia).


Diagnosis and Therapeutic Actions

(H3) During the 15-minute procedure, Dr Tiong can perform several vital clinical tasks:


  • Biopsies: Taking small tissue samples to check for H. pylori (a bacteria linked to ulcers), Coeliac disease, or Barrett’s Oesophagus.
  • Polyp Removal: Identifying and removing small growths before they become problematic.
  • Stricture Dilation: Gently stretching a narrowed oesophagus to improve swallowing.
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The Procedure & Preparation

Because the specialist needs a clear view of the stomach lining, your stomach must be completely empty. Safety is our primary concern.


Preparing Your Stomach (Fasting)


  • No Food: You must not eat any solid food for at least 6 hours before your procedure.
  • Clear Fluids: You may usually drink small amounts of water up until 2 hours before your appointment.
  • Medications: It is vital to tell us if you are on blood thinners or diabetes medication. Most other medications can be taken as normal with a small sip of water.


Your Comfort: Throat Spray vs. Conscious Sedation

At 1 Health, we tailor the experience to your preference. You typically have two options:


  • Local Anaesthetic Spray: A spray that numbs the back of your throat. You remain fully awake, but the "gag reflex" is significantly suppressed. You can usually drive home immediately after.
  • Conscious Sedation: An injection that makes you feel very relaxed and drowsy. While not a general anaesthetic, most patients find they have no memory of the procedure afterward. Note: This requires a mandatory driver to take you home.

Frequently Asked Questions & Risks

  • Will I gag or feel like I can’t breathe during the gastroscopy?

    You will usually be given conscious sedation, which relaxes you for the procedure, but doesn’t completely “knock you out” like a general anaesthesia. However, people often fall asleep during the earlier part of the procedure, and may not have memory of the procedure due to the sedative effects.

  • How long do I need to fast before the procedure?

    The procedure itself typically takes between 30 to 45 minutes, depending on whether polyps need to be removed. however, you should plan to be at our Wigram clinic for approximately 2 to 3 hours in total. This allows time for pre-procedure admission, the procedure itself, and about an hour in our recovery suite as the sedation wears off.

  • Can I go back to work the same day?

    Dr Tiong will usually speak with you briefly in the recovery room once you are awake to give you a preliminary visual report. If the bowel was clear and nothing was found, you will know immediately. However, if biopsies were taken or polyps removed, these are sent to a laboratory for analysis. Formal pathology results typically take 7 to 10 working days. We will send a full report to both you and your GP as soon as these are finalised.

  • What are the actual risks of a gastroscopy?

    The success of a colonoscopy depends entirely on a clear view of the bowel lining. If residual stool remains, it can hide small polyps or early-stage cancers. If you are struggling to finish the prep or experience significant vomiting, please call the clinic immediately. We may be able to suggest an alternative "prep" or adjust your schedule. It is better to troubleshoot the prep than to have an incomplete examination that needs to be repeated.

  • What is Dr Tiong looking for during the exam?

    A gastroscopy allows for a much more detailed view than an X-ray or CT scan. Dr Tiong is looking for signs of inflammation (gastritis), ulcers in the stomach or duodenum, signs of Coeliac disease, or a condition called Barrett’s Oesophagus (often caused by long-term acid reflux). Biopsies are often taken to test for H. pylori, a common bacteria that can cause stomach issues.

  • Do I need to stop my regular medications?

    Most medications can be taken as usual with a small sip of water. However, blood thinners (e.g., Warfarin, Dabigatran, Aspirin) and diabetes medications (e.g., Insulin or Metformin) require special management. Dr Tiong will provide you with a specific plan during your consultation. Do not stop any prescribed heart or blood pressure medication unless specifically instructed by our clinical team.