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Colonoscopy

Dr Thng Yongxian

Hepatopancreatobiliary & General Surgeon
MBBS • MMed • MRCS (IRE) • FRCSED • FAMS

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What is Colonoscopy?

A colonoscopy is a diagnostic procedure that visually examines the interior of the colon and rectum using a flexible, camera-equipped tube called a colonoscope. This procedure is important for detecting colon polyps, cancers, and other conditions, affecting the large intestine.

 

Colonoscopy is recommended as a routine screening tool for colorectal cancer starting at age 45 for people at average risk. It can also help diagnose symptoms such as unexplained changes in bowel habits, rectal bleeding, and abdominal pain. The procedure not only aids in diagnosis but can also be therapeutic, allowing for the removal of polyps and tissue sampling.

When Is a Colonoscopy Recommended?

A consultation with a colonoscopy specialist may be recommended for several key reasons, ranging from routine screening to investigating specific symptoms. The main indications include:

  • Routine Cancer Screening: For individuals at average risk, regular screening for colorectal cancer is typically advised starting from age 45-50. This may be recommended earlier for those with significant risk factors.

  • Investigation of Symptoms: A colonoscopy is crucial for investigating symptoms such as rectal bleeding, chronic constipation or diarrhoea, persistent abdominal pain or bloating, unexplained weight loss, and changes in bowel habits.

  • Further Evaluation: It is often required to determine the cause of iron-deficiency anaemia or to follow up on abnormalities found on other tests like a CT scan or a Faecal Immunochemical Test (FIT).

  • Surveillance: Patients with a personal or strong family history of colorectal cancer or polyps, or those with inflammatory bowel disease (IBD) like Crohn's disease or ulcerative colitis, require periodic colonoscopies for surveillance.

Benefits of Colonoscopy

A colonoscopy is considered the gold standard for colorectal health for several reasons. It offers distinct advantages over other screening methods by providing comprehensive and actionable insights. The key benefits include its high accuracy and safety profile, its function as a real-time diagnostic tool with biopsy capabilities, and most importantly, its unique ability to both detect early-stage colorectal cancer and prevent it from developing by removing precancerous polyps during the same procedure.

Preparing for a Colonoscopy

A successful colonoscopy relies on proper bowel preparation to ensure the colon is thoroughly clean, allowing for a clear and accurate examination. Here are the key steps involved when preparing for your appointment at a colonoscopy clinic Singapore:

Dietary Restrictions

  • In the days leading up to the procedure, you will be required to follow a special low-fibre diet. For at least 24 hours before your colonoscopy, you will need to consume only clear liquids. This includes water, clear broths, black coffee or tea (without milk), and clear juices like apple juice. Avoid red or purple-coloured drinks.

Bowel Preparation

  • To cleanse your colon completely, you must take a laxative preparation prescribed by your colonoscopy doctor. This may be a large volume of liquid that you drink over several hours or a smaller volume solution taken with other clear fluids. This preparation will induce diarrhoea to empty the colon, so it is important to stay at home and near a toilet during this time.

Medication Adjustments

  • It is crucial to discuss all medications, supplements, and health conditions with your doctor before your procedure. Some medications, particularly blood thinners (like aspirin, clopidogrel, or warfarin) and diabetes medications, may need to be adjusted or temporarily discontinued to ensure your safety during the procedure.

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Pre-Procedure Setup

Upon arrival at the clinic or hospital, you will be required to complete the necessary paperwork and change into a gown. You’ll then be taken to the procedure room.

Sedation

Most colonoscopies are performed under sedation to ensure comfort throughout the procedure. You will receive sedatives intravenously, which will make you feel drowsy.

Insertion of the Colonoscope

A long, flexible tube called a colonoscope will be inserted into the rectum and gently advanced through the colon. The colonoscope has a light and camera that sends images to a monitor, allowing it to examine the intestinal lining.

Examination and Intervention

As the colonoscope is manoeuvred through the colon, it is used to identify abnormalities like polyps or signs of inflammation. Tools can be passed through the colonoscope to remove polyps, take biopsies, or perform other necessary interventions.

Withdrawal and Inspection

The colonoscope is slowly withdrawn while the lining of the colon is inspected for any additional findings.

What Happens During Colonoscopy?

Understanding the procedure can help alleviate any anxiety. Our colonoscopy services are designed for patient comfort and safety.

  • Pre-Procedure Setup: Upon arrival at the clinic or hospital, you will complete the necessary paperwork and change into a medical gown. A nurse will review your medical history, and an intravenous (IV) line will be placed in your arm.

  • Sedation: To ensure you are comfortable and relaxed, most colonoscopies are performed under sedation. The sedative is administered through the IV, making you feel drowsy and relaxed. You will likely not remember the procedure afterward.

  • The Procedure: Once you are sedated, you will lie on your side, and your doctor will gently insert the colonoscope into your rectum. Air or carbon dioxide will be slowly introduced into the colon to inflate it slightly, allowing for a better view of the intestinal lining. The flexible colonoscope is carefully advanced through the entire length of the colon while images from the camera are transmitted to a monitor.

  • Examination and Intervention: As the colonoscope is withdrawn, the lining of the colon is meticulously inspected for any abnormalities. If polyps are found, they can usually be removed immediately using tiny tools passed through the scope. Tissue samples (biopsies) can also be taken for further analysis. The entire procedure typically lasts about 20 to 30 minutes.

Recovery and Aftercare Following Colonoscopy

It is important to follow specific aftercare instructions to ensure a smooth recovery after your colonoscopy. Here’s what you can generally expect:

  • Immediate Post-Procedure Care: After the colonoscopy, you will be taken to a recovery area, where nurses will monitor you as the effects of sedation wear off. This usually takes about 1 to 2 hours. You may feel mild cramping or bloating due to the air introduced into your colon; moving and walking can help relieve this discomfort.
  • Observation for Complications: Although complications are rare, it’s important to monitor for any signs of trouble, such as severe abdominal pain, fever, bloody stool, or heavy bleeding from the rectum.
  • Resuming Diet and Activities: You can usually eat and drink normally soon after the procedure unless advised otherwise. Most people can return to normal activities the following day.
  • Managing Discomfort: You might experience mild cramping or bloating due to air introduced into the colon during the procedure. Walking and moving around can help dispel gas and alleviate discomfort.

  • Receiving Your Results: Your colonoscopy doctor will discuss the initial findings with you after the procedure. If biopsies were taken or polyps were removed, the results from the laboratory analysis will typically be available within a week.


    Complications from a colonoscopy in Singapore are rare but possible. Contact your doctor immediately if you experience severe abdominal pain, a firm or bloated abdomen, persistent vomiting, fever, or significant rectal bleeding (more than a few tablespoons).

Dr Thng Yongxian

Senior Consultant

HEPATOPANCREATOBILIARY & GENERAL SURGEON

MBBS (SG) • MMed (Surg) • MRCS (Ire) • FRCSEd (Gen) • FAMS (Surg)

Dr Thng Yongxian specialises in comprehensive colonoscopy services for screening and surveillance, utilising advanced image-enhanced techniques such as NBI, i-scan, and chromoendoscopy.
  • Bachelor of Medicine & Bachelor of Surgery
  • National University of Singapore
  • Membership of the Royal College of Surgeons, Ireland
  • Master of Medicine, General Surgery, Singapore
  • Fellow of the Royal College of Surgeons, Edinburgh
  • Fellow of the Academy of Medicine, Singapore

Dr Thng Yongxian is a hepatopancreatobiliary surgeon with expertise in comprehensive colonoscopy service for screening, surveillance, and therapeutic polypectomy. His practice provides patients with the full spectrum of diagnostic procedures including: i-enhanced colonoscopy using NBI, i-scan, and chromoendoscopy; IBD surveillance colonoscopy aligned with SCENIC recommendations using targeted and random biopsies; therapeutic colonoscopy for bleeding control, dilation, and foreign body retrieval. He is also well-known for pioneering the use of capsule colonoscopy for colorectal screening.

 

Dr Thng obtained his subspecialty training in Hepatopancreatobiliary surgery at Singapore General Hospital followed by a clinical fellowship in Minimally Invasive Hepatopancreatobiliary Surgery at Seoul National University Hospital in Bundang, South Korea.

 

Dr Thng Yongxian also serves on various committees at hospital, cluster, and ministry levels, contributing to policy and standards of care. Most notably, he has served as a member of the Ministry of Health (MOH) Laparoscopic Cholecystectomy Clinician workgroup for value-driven care.

Education

  • Bachelor of Medicine & Bachelor of Surgery
  • National University of Singapore
  • Membership of the Royal College of Surgeons, Ireland
  • Master of Medicine, General Surgery, Singapore
  • Fellow of the Royal College of Surgeons, Edinburgh
  • Fellow of the Academy of Medicine, Singapore

Frequently Asked Questions about Colonoscopy

Is colonoscopy painful?

No, a colonoscopy is not considered painful. The procedure is performed under sedation to ensure you are comfortable and relaxed. While you may feel some bloating or mild cramping from the air used to inflate the colon, you should not experience pain during the examination.

A colonoscopy is the gold standard for detecting colon cancer and precancerous polyps, with very high accuracy. It allows for a direct visual inspection of the entire colon lining. While it is the most effective tool available, no medical procedure is 100% perfect, and there is a very small chance that tiny or flat polyps could be missed.

Recovery after a colonoscopy is typically very quick. You will need 1-2 hours at the clinic for the sedation to wear off. Most people feel back to normal by the next day and can resume their usual diet and activities. You should not drive or make important decisions for 24 hours after the procedure due to the effects of sedation.
For average-risk individuals with a normal result, a screening colonoscopy is recommended every 10 years. If polyps are found, or if you have other risk factors like a family history of colon cancer or IBD, your colonoscopy doctor will recommend more frequent surveillance, typically every 1-5 years, depending on the findings.
A FIT is a non-invasive screening test that checks for tiny amounts of hidden blood in your stool, which can be a sign of cancer or large polyps. It is a good first-step screening tool. However, a colonoscopy is a diagnostic procedure. If a FIT test is positive, a colonoscopy is required to find the source of the bleeding, confirm a diagnosis, and remove any polyps found.
CT colonography uses a CT scanner to create 2D and 3D images of the colon. While it is less invasive than a conventional colonoscopy, it still requires the same bowel preparation. Its main limitation is that if polyps or other abnormalities are found, a standard colonoscopy must still be performed to remove them or take a biopsy. A conventional colonoscopy allows for both diagnosis and immediate therapeutic intervention in a single session.

Corporate and Personal Insurance Plans

Our Clinic Location

Precision Surgical Centre
@ Gleneagles Hospital Annexe Block

Precision Surgical Centre @ Gleneagles Hospital Annexe Block

Clinic Locations

Nexus Surgical @ Mt. Alvernia

Nexus Surgical @ Mt. Elizabeth Orchard

Nexus Surgical @ Mt. Elizabeth Novena

Nexus Surgical @ Parkway East

Nexus Surgical @ Gleneagles Medical Centre

Nexus Surgical @ Mt. Alvernia

Nexus Surgical @ Mt. Elizabeth Orchard

Nexus Surgical @ Mt. Elizabeth Novena

Nexus Surgical @ Parkway East

Nexus Surgical @ Gleneagles Medical Centre

Nexus Surgical @ Mt. Alvernia

Nexus Surgical @ Mt. Elizabeth Orchard

Nexus Surgical @ Mt. Elizabeth Novena

Nexus Surgical @ Parkway East

Nexus Surgical @ Gleneagles Medical Centre

Need help navigating your health?

Dr. Thng Yongxian extensive surgical experience includes specialised expertise as both a liver cancer surgeon and a gallbladder specialist. If you wish to learn more about our colonoscopy services or our other specialised treatments in Singapore, please contact our clinic today.