Colonoscopy

Dr Calvin Ong

mbbs M.Med (Surgery) MRCS FRCS

Indications Preparation Procedure Post-Colonoscopy Risks Results FAQ

What Is A Colonoscopy?

A colonoscopy is a medical procedure that enables doctors to inspect the inner lining of the large intestine, including the colon and rectum.

This examination aids in detecting abnormalities such as inflamed tissue, ulcers, polyps, and cancer. It is used for the early detection and prevention of colorectal cancer, which is the most common cancer in Singapore. It is also useful for diagnosing conditions like Crohn’s disease, ulcerative colitis, and diverticulosis. Colonoscopy also helps in identifying the causes of symptoms such as chronic diarrhoea, abdominal pain, change in bowel habits and rectal bleeding.

Indications for Colonoscopy

Colonoscopy is recommended for several reasons, including screening, diagnosis, and monitoring of various colon and rectum conditions:

Screening for Colorectal Cancer

Recommended starting at age 50 or earlier for individuals with a family history of colorectal cancer or polyps.

Detection and Removal of Polyps

Identifies and removes polyps, lowering the risk of cancer development.

Evaluation of Symptoms

Investigates unexplained symptoms such as chronic diarrhoea, abdominal pain, rectal bleeding, changes in bowel habits, and unexplained weight loss.

Follow-up on Abnormal Imaging or Tests

Used to further investigate abnormalities found in other tests and to obtain tissue samples if necessary.

Monitoring Inflammatory Bowel Disease

Regularly performed for patients with Crohn’s disease or ulcerative colitis to monitor disease progression and assess treatment effectiveness.

Assessment of Anaemia

Helps determine the cause of iron deficiency anaemia due to potential gastrointestinal bleeding.

Surveillance After Polyp or Cancer Removal

Patients with a history of polyps or colorectal cancer may require periodic colonoscopies to monitor for recurrence or new polyps, depending on the doctor’s recommendations.

Preparing for a Colonoscopy

Proper preparation is required to achieve a clear view of the colon during a colonoscopy. The preparation involves several steps:

Dietary Restrictions

Patients should follow a low-fibre diet for a few days before the procedure, avoiding whole grains, nuts, seeds, dried fruits, and raw vegetables. The day before the colonoscopy, patients must switch to a clear-liquid diet, which includes broth, clear juices, and gelatin. Red, purple, or blue liquids should be avoided, as they can discolour the colon lining.

Bowel Preparation

Patients must take a bowel-cleansing agent as prescribed by their doctor. This typically involves drinking a large volume of a special solution or taking oral laxatives to empty the colon. The instructions may vary, but the goal is to have clear or light yellow stool at the end of the preparation.

Medication Adjustments

Patients should inform their doctor about any medications they are taking, including over-the-counter drugs and supplements. Certain medications, such as blood thinners, may need to be adjusted or temporarily discontinued to reduce the risk of bleeding during the procedure.

Clear Fluids Only

On the day of the colonoscopy, patients should not eat or drink anything other than necessary medications and a small sip of water.

Transport arrangements

Due to the sedation used during the procedure, patients must arrange for transportation home following the colonoscopy. It is unsafe to drive or operate machinery for the remainder of the day.

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Step-by-Step Procedure

Here is what to expect during a colonoscopy, from arrival at the clinic to the completion of the procedure:

Arrival and Pre-Procedure Preparation

Upon arrival at the clinic, the patient will be asked to change into a hospital gown. A nurse will review the patient’s medical history and current medications, and confirm the completion of the bowel preparation. An intravenous (IV) line will be inserted into the patient’s arm to administer sedatives and fluids.

Administration of Sedation

The patient will be given a sedative through the IV line to help them relax and minimise discomfort during the procedure. Depending on the level of sedation, the patient may be fully asleep or just relaxed and drowsy.

Insertion of the Colonoscope

The patient will lie on their side with their knees drawn towards the chest. The doctor will gently insert the colonoscope into the rectum and gradually advance it through the colon. The scope’s camera transmits images to a monitor, allowing the doctor to examine the colon’s lining.

Examination and Intervention

As the colonoscope is advanced, the doctor carefully examines the entire length of the colon. If any polyps or abnormal tissues are found, they can be removed using special instruments passed through the colonoscope. Tissue samples (biopsies) may also be taken for further analysis.

Withdrawal of the Colonoscope

After the examination and any necessary interventions, the doctor will slowly withdraw the colonoscope. The procedure typically takes 30 to 60 minutes, depending on the findings and any interventions performed.

Post-Colonoscopy Care

Proper care after a colonoscopy ensures a smooth recovery.

Immediate Care

Patients will be monitored in a recovery area until the sedation wears off, usually taking 30 minutes to an hour. Vital signs such as blood pressure, heart rate, and oxygen levels will be checked regularly. Mild bloating or cramping may occur due to the air introduced into the colon during the procedure.

Recovery Process

Most patients can resume normal activities the day after the procedure but should rest for the remainder of the day. Mild discomfort, bloating, or gas usually resolves within a few hours. Drinking plenty of fluids helps flush out any remaining bowel-cleansing agent.

Dietary Recommendations

Start with light meals and gradually return to a normal diet. Avoid heavy, greasy, or spicy foods initially to prevent gastrointestinal discomfort.

Follow-up

If polyps were removed or biopsies taken, results typically take several days to a week. The doctor will discuss findings and any further steps needed.

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Risks and Complications

Colonoscopy is generally a safe procedure, but as with any medical intervention, it carries some risks and potential complications. Patients should be aware of these risks and discuss any concerns with their doctor before undergoing the procedure.

Risks

The potential risks associated with a colonoscopy include:

Bleeding: Minor bleeding can occur at biopsy sites or where polyps were removed. This is usually self-limiting but may require medical attention if it persists.
Abdominal Discomfort: Some patients experience bloating, cramping, or mild discomfort due to the air introduced into the colon. This typically resolves within a few hours.
Perforation: There is a small risk of a tear or perforation in the colon wall, which may require surgical repair.
Infection: Although rare, infections can occur, particularly if a polyp is removed or a biopsy is taken.

Post-Procedure Complications

Potential post-procedure complications include:

Severe Pain: Severe abdominal pain after the procedure may indicate a complication such as perforation or infection.
Heavy Bleeding: Heavy or prolonged rectal bleeding should be reported to your doctor immediately.

Results and Follow-up

Immediate Results: The doctor often shares initial findings right after the procedure. If polyps or abnormal tissues were removed, preliminary information will be provided.

Biopsy and Polyp Removal: Samples sent to the lab for analysis typically take a few days to a week. The doctor will follow up to discuss results and any further actions.

Normal Results: If no abnormalities are found, the next routine screening is usually scheduled in 10 years for average-risk patients.

Abnormal Results: If polyps, inflammation or other abnormal issues are detected, the doctor will recommend further tests, more frequent surveillance, or specific treatments.

Follow-up Appointments: Patients with specific conditions, such as large polyps, multiple polyps, or inflammatory bowel disease, may require more frequent colonoscopies, with a tailored surveillance plan from their doctor.

Dr Calvin Ong Jianming

Senior Consultant, Colorectal & General Surgeon

MBBS (S’pore)|

M.Med (Surgery)|

MRCS (Ireland)|

FRCS (Edin)|

王健名医生

Dr. Calvin Ong is a Senior Consultant with more than 15 years of surgical experience. He specializes in colorectal and general surgery, performing minimally invasive as well as advanced robotic surgeries for benign and malignant colorectal conditions, including inflammatory bowel disease, pelvic floor disorders, colorectal cancer, and hernia repair. He is dedicated to providing high-quality, personalised care for his patients.

Dr. Ong graduated with a Bachelor’s degree in medicine and surgery from the National University of Singapore in 2008 and completed his Masters of Medicine (Surgery) at the same institute. He finished his advanced specialist training in 2016 and became a fellow of the Royal College of Surgeons of Edinburgh.

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