Digestive health is crucial to our overall well-being, yet many gastrointestinal (GI) issues can remain undiagnosed until symptoms significantly worsen. This delayed diagnosis often leads to more complex treatments and poorer outcomes. Advanced visualization techniques like Oesophago-Gastro-Duodenoscopy (OGD) and colonoscopy allow medical professionals to examine the digestive tract directly. These procedures serve as diagnostic tools for the early detection of various GI conditions, from inflammation and ulcers to polyps and cancer.

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What is an Oesophago-Gastro-Duodenoscopy (OGD)?

Oesophago-Gastro-Duodenoscopy (OGD), also known as gastroscopy or endoscopy, is a diagnostic procedure examining the upper digestive tract. This examination includes the esophagus (food pipe), stomach, and duodenum (the first part of the small intestine). The procedure is performed by a specialized medical professional called an endoscopist.

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During an OGD procedure, the endoscopist uses an endoscope—a thin, flexible tube approximately 9-12mm in diameter—which is carefully passed through the mouth and guided down into the stomach and duodenum. The endoscope is equipped with a high-definition camera and light source at its tip, which transmits clear, detailed images to a monitor in real time. This allows the endoscopist to thoroughly inspect the lining of the upper GI tract for any abnormalities.
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• Persistent upper abdominal pain
• Difficulty swallowing (dysphagia)
• Frequent heartburn or acid reflux
• Unexplained weight loss
• Persistent nausea or vomiting
• Iron deficiency anemia
• Black or tarry stools (indicating potential bleeding in the upper GI tract)

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The endoscopy procedure enables visual examination and allows for tissue sampling (biopsy) if suspicious areas are identified, making it a critical diagnostic tool for conditions like gastritis, stomach ulcers, Barrett's esophagus, and even early-stage stomach cancer.

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When Should You Get an OGD?

An OGD is typically recommended when patients are faced with specific symptoms that might indicate upper digestive tract issues.

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These symptoms include:

• Persistent upper abdominal pain
• Difficulty swallowing (dysphagia)
• Frequent heartburn or acid reflux
• Unexplained weight loss
• Persistent nausea or vomiting
• Iron deficiency anemia
• Black or tarry stools (indicating potential bleeding in the upper GI tract)

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The endoscopy procedure enables visual examination and allows for tissue sampling (biopsy) if suspicious areas are identified, making it a critical diagnostic tool for conditions like gastritis, stomach ulcers, Barrett's esophagus, and even early-stage stomach cancer.

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What is a Colonoscopy?

A colonoscopy is a comprehensive examination of the inside of the large intestine, including the colon, rectum, and anus. This procedure uses a colonoscope—similar to the instrument used in an OGD but longer—to visualize the entire length of the large bowel.

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During a colonoscopy, the doctor searches for changes in the large intestine and rectum that could indicate health problems. These changes include swollen or irritated tissues, polyps (abnormal growths that can become cancerous), or signs of colorectal cancer. The high-resolution camera on the colonoscope allows for a detailed examination of the intestinal lining. At the same time, specialized tools can be passed through the scope to remove polyps or take tissue samples for further analysis.

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When Should You Get a Colonoscopy?

Colonoscopy examinations are recommended based on a comprehensive assessment of risk factors, symptoms, and evidence-based screening guidelines.

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• Screening for colorectal cancer, especially for individuals over 50 or those with family history
• Investigating causes of abdominal pain, rectal bleeding, or chronic diarrhea
• Diagnosing inflammatory bowel diseases like Crohn's disease or ulcerative colitis
• Exploring unexplained changes in bowel habits
• Following up on abnormal results from other tests, such as blood tests or imaging studies
• Treating certain conditions, such as removing polyps or stopping intestinal bleeding

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What is the Difference Between OGD and Colonoscopy?

OGD and colonoscopic procedures both examine the digestive tract, but they differ in certain key aspects, from preparation requirements to recovery processes:

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Area Examined

OGD: Focuses on the upper GI tract (esophagus, stomach, and duodenum)

Colonoscopy: Examines the lower GI tract (colon, rectum, and anus)

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Sedation and Procedure Duration

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Recovery Process

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Potential Findings During Procedure

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Can OGD and Colonoscopy Be Performed Together?

It’s possible to undergo an OGD and colonoscopy in a single session.This combined approach, sometimes called a bidirectional endoscopy or "both upper and lower endoscopy," comprehensively evaluates the entire GI tract in one visit. The combined procedure benefits patients with symptoms that could originate from either the upper or lower digestive tract or those with a family history of multiple GI conditions. Having both procedures performed together saves time, reduces costs, and requires only one session of sedation.

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The specialist will perform the OGD first during the combined procedure, followed by the colonoscopy. This ordering minimizes the risk of aspiration and provides a logical sequence for examining the digestive system. The combined procedure usually takes 45-90 minutes, depending on findings and any therapeutic interventions needed.

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Preparation for a Combined OGD and Colonscopy Procedure

The preparation for a combined endoscopy procedure follows the more stringent requirements of the colonoscopy, including:

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• Complete bowel cleansing with an oral laxative (bowel prep)
• Fasting from solid foods for at least 24 hours before the procedure
• Drinking only clear liquids until about 8 hours before the procedure
• Temporarily discontinuing certain medications like blood thinners, iron supplements, and constipating agents approximately one week before the procedure

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Preventive Gastroenterology: The Impact of Early Detection

OGD and colonoscopy represent the strong pillars of modern gastroenterology. These procedures allow medical specialists to visualize, diagnose, and treat various conditions through the digestive tract. Performed separately or combined in a single session, OG and colonoscopy are key procedures that can offer critical insights leading to early intervention, potential prevention, and improved health outcomes. These procedures are significant for the ageing Hong Kong population and those with family histories of digestive disorders.

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Remarks:

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