Colonoscopy Screening for Colorectal Cancer

What is Colonoscopy?

Colonoscopy is a day surgery procedure to inspect the inner lining of the colon and rectum. It is useful for both diagnostic and therapeutic purposes from checking a person for cause of per rectal bleeding till even removal of early cancers. The procedure will require pre-procedural bowel preparation which is often regarded as being unpleasant. 

Thankfully, there are alternatives that can be discussed with your physician. The alternatives will still require the use of laxatives but with increased tolerability. A clean bowel preparation is essential for the accuracy and reproducibility of the colonoscopy outcome.

The procedure itself is frequently done under sedation although some patients may request to do without. In all cases, patients often don’t remember the procedure due to the sedation or don’t feel any pain. It involves passing a long flexible tube through the anus and takes about 15 to 20 minutes to complete. 

Upon the detection of any polyps, these are usually removed unless contraindicated. The results of any tissue testing i.e., histology can take up to 1 week. Post procedure, patients will be advised to avoid any exercise or manual work. If sedation was given, it is also advisable to not sign any legal documents or make important decisions as it will take some time before the sedatives are eliminated from the body. 

Other side effects may include bloatedness or nausea and vomiting, but these are self-limiting and goes away within a day. Many may find this invasive procedure risky. However, the risk of this procedure is indeed very rare. The risks of colonoscopy include perforation and bleeding of which a perforation is where a puncture is made in the colon and may require an operation to repair the puncture. The estimated risks of such severe complications is less than 0.1%

Alternatives include CT colonography, flexible sigmoidoscopy, occult blood testing in stool and rarely Barium enema. These alternatives are used only in specific situations and are not always reasonable alternatives depending on the clinical indication. Hence, the advice is to discuss these with a physician to have the best choice for your needs.

Who Should Go for a Colonoscopy?

Colonoscopy is often used to detect colorectal cancer, as well as other diseases such as inflammatory bowel disease and polyps. There are several key factors that may indicate that a person should have a colonoscopy. 

If you have any of the following symptoms of colorectal cancer or a positive result for your Fecal Occult Blood Test or Faecal Immunochemical Test, you should consider going for colonoscopy. Possible symptoms of colorectal cancer are: abdominal pain, a change in bowel habits, sudden or unexplained weight loss, and blood in stools.

Additionally, it is also important for those with a family history of colorectal cancer or polyps to go for a colonoscopy. This is because individuals with a family history of colorectal cancer or polyps are at a greater risk for developing the disease. A colonoscopy can help to identify any precancerous polyps that may be present, so that they can be removed before they turn into cancer.

Finally, all individuals aged 50 and above should go for a colonoscopy, regardless of their medical history. This is because the risk of developing colorectal cancer increases significantly with age, and a colonoscopy can help to catch any precancerous polyps that may be present. In the US, the age limit is lower, where all individuals aged 45 and above are advised to go for a colonoscopy. 

Overall, if you show symptoms of colorectal cancer, have a family history of colorectal cancer or polyps, or are 50 years old and above, it is important to go for a colonoscopy. 

A colonoscopy can help to identify any precancerous polyps that may be present, so that they can be removed before they turn into cancer.

How Should You Prepare for a Colonoscopy?

The first step to preparing for your colonoscopy is to clear your colon of solid waste.  This is typically done by taking a prescribed laxative or a bowel cleansing preparation. Most of these preparations are taken the night before the procedure, but you should follow your doctor’s instructions carefully to make sure that your colon is clear before the appointment. 

If your colon is not cleared properly, remaining solid waste may obstruct your doctor from getting a clear view, and you may need to reschedule your colonoscopy. To make matters worse, you may have to repeat the entire bowel preparation and take more! Hence it is vital to follow the instructions meticulously to ensure a good quality colonoscopy being performed. 

You may also need to take or avoid certain medications before your colonoscopy. Therefore, be sure to tell your doctor about any medications that you are currently taking, especially those to do with blood thinning. Patients who need this include people with a history of stroke or heart attack. 

It is also important to follow any other instructions that your doctor has given you prior to the procedure. This may include avoiding certain foods, such as dairy and red meat, as well as avoiding alcohol and cigarettes. You may also need to fast for a period of time before the procedure.

By following these steps, you can help ensure that your colonoscopy goes smoothly and that your doctor gets a clear view of your colon. Remember to follow your doctor’s instructions carefully, and to contact him or her if you have any questions or concerns prior to the appointment.

What Can You Expect During a Colonoscopy?

When you arrive for your colonoscopy, you will be given light sedation to help you relax and make the experience as comfortable as possible. The procedure itself only takes between 10 and 20 minutes. During the colonoscopy, the doctor will insert the endoscope into your colon through your anus and examine the inside of your large intestine. 

Depending on what they find, they may take a biopsy or remove any polyps they find. Once the procedure is over, you will be moved to a day surgery ward for observation until the sedative wears off. Once the sedative has worn off, light snacks and drinks will be provided. 

Your doctor will then visit you to discuss the findings of the procedure. They will tell you about any polyps or abnormalities that were found, as well as what the next steps should be. While a colonoscopy may sound intimidating, it is usually a relatively straightforward procedure with minimal or no discomfort. 

In addition to helping your doctor diagnose any issues, having a colonoscopy can also help you reduce your risk of colon cancer. So, if you’re due for a colonoscopy, rest assured that it’s a safe and effective procedure that can help keep you healthy.

What Can You Expect After the Procedure?

After a colonoscopy, it is important to take some time to rest and let the effects of the sedative wear off before continuing with your normal daily activities. It is typically recommended to have someone else drive you home as the effects of the sedative can take up to a full day to fully pass. You may feel bloated or pass gas for a few hours after the procedure as you clear the air from your colon and walking can help to ease any discomfort.

It is also normal to notice a small amount of blood with your first bowel movement after the procedure. Generally, this is nothing to worry about however if you continue to pass blood or blood clots, experience persistent abdominal pain or have a fever, it is important to contact your doctor. It is rare but possible for delayed complications to occur from the procedure that could take up to 1 week to appear. 

Once the sedative is out of your system, you should be able to return to your normal routines and activities. Some patients report feeling more energetic and alert after the colonoscopy as the procedure can help to detect and prevent the potential for health problems down the road. 

Overall, the effects of a colonoscopy can be positive and can help to protect your health in the long-term. It is important to be mindful of any potential complications or odd sensations that you may experience after the procedure and to discuss them with your doctor if they persist or worsen.

What are Some of the Risks of Colonoscopy?

Colonoscopy is a procedure used to check the inside of the large intestine for abnormalities, such as polyps, growths, or cancer. It’s an important part of screening for colon cancer and is used to diagnose and treat certain digestive disorders.

Although colonoscopy is generally safe, it does carry some risks. As with any medical procedure, it’s important to be aware of the potential risks of colonoscopy before the exam.

Risks of colonoscopy can be related to the anesthesia used during the procedure. There is a risk of an allergic reaction to the sedative, which can cause difficulty breathing, a rash, or hives. In rare cases, the patient may experience a severe reaction that requires emergency medical care.

Another risk is bleeding from the site where a tissue sample (biopsy) was taken or a polyp or other abnormal tissue was removed. Although this type of bleeding is usually minor and stops on its own, it can sometimes require treatment.

A third risk is a tear in the colon or rectum wall (perforation). This is a rare complication that can occur when the scope is inserted into the colon. It can cause severe abdominal pain and requires emergency medical attention including surgery to repair the tear.

Before a colonoscopy, the doctor will discuss these risks with you and ask you to sign a consent form giving permission for the procedure. It’s also important to tell your doctor about any medical conditions you have that may increase your risk of complications from the procedure.

Although colonoscopy carries some risks, the procedure is generally safe and helps to detect serious problems early. If you’re due for a colonoscopy, talk to your doctor about the risks and any concerns you may have before the exam.

Frequently Asked Questions

  • Is colonoscopy a painful procedure?

    Colonoscopy is not a painful procedure. Some patients in fact opt to do it without any sedation or pain killers. The reason for most colonoscopy to be done under sedation is to relieve the anxiety patients go through when the scope is traversing the large intestine.

    After the procedure, it is very common for patients to not remember anything about what was done. Thankfully, pictures and videos are usually taken during the procedure to reassure the patient that he did go through the scope and the results are usually given back on the day itself.

  • What diseases can be detected through colonoscopy?

    Colonic polyps, colorectal cancer, inflammatory bowel disease like Crohn’s disease, diverticular disease, colitis, angiodysplasia, piles and other rarer findings like gastrointestinal tumor can all be found during the colonoscopy.

    It is of note that a colonoscopy just examines the large intestine and examination of the small intestine is not required as it is very uncommon to detect diseases in the small intestine. The terminal ileum may be intubated to check for lymphomas, infection like tuberculosis or inflammatory bowel disease like Crohn’s.

  • How long will a colonoscopy take?

    It usually takes less than 20 mins to complete a colonoscopy. The reason is because most colonoscopies are uncomplicated and do not require multiple interventions like polypectomies and multiple biopsies. There are some reasons for which the duration is longer than 1 hour.

    For example, the removal of a huge polyp via endoscopy also termed endoscopic submucosal dissection. This requires a skilled endoscopist with the necessary equipment to allow for safe dissection and removal of a huge polyp through the scope thereby avoiding the need for a major surgery.

  • How much will a colonoscopy cost?

    The cost of the colonoscopy varies depending on the complexity of the procedure. The fee benchmark provided by MOHH 2020 applies to most colonoscopies. The surgeon’s fee range for a colonoscopy without polypectomy is about $1,100 to 1,600 SGD. The facilities fees will depend on the day surgery center or hospital that the scope is performed in.

  • How long is the recovery period for colonoscopy?

    After the procedure, most patients are monitored for 1 to 2 hours. After which, they will be ready for discharge. Patients are advised not to do any work on the day itself and also not to sign any important documents as they may continue to have drowsiness and temporary memory loss during this period of time. They should be fully functional the very next day and there are long term no side effects from the colonoscopy.

  • What are the dos and don’ts of colonoscopy?


    1. Always check with the doctor about the indication of the colonoscopy. Not all patients need colonoscopy especially the time frame for the next colonoscopy after having one before
    2. Plan your colonoscopy in a stress free period where you can comfortably be excused from work. Although most patients can opt to go back to work the next day (some even the afternoon on the day itself!), but it would be advisable to rest with 2 days of hospitalization leave.
    3. Do follow the bowel preparation regime in order to have a smooth and good quality colonoscopy done. This gives the best assurance that the colon is cancer free.

    Do Nots

    1. Avoid planning your colonoscopy during festivals or big celebrations. Most people forget about their diet restrictions! Especially for patients who are older, it is very important to follow the diet restrictions as their colon tends to have poorer motility and the bowel preparation may not be as effective as compared to the younger counterparts.
    2. Avoid sleeping late during the days leading up to the day of scope. As the preparation takes time and often results in shorter hours of sleep the day before scope. This might lead to you waking up late and arriving late on the day of scope.
    3. Avoid doing work during your bowel preparation on the day before scope. This is because the bowel preparation requires multiple trips to the toilet and the bowel preparation is not effective if you sip it like coffee and work at the same time.
    4. Avoid driving on the day of your scope. This is due to the drowsiness that can persist even after the colonoscopy on the day of scope. It is safer to take a taxi or Grab or have someone pick you up.
    5. Avoid wearing tight clothes on the day of scope. After colonoscopy, some patients may still feel somewhat bloated due to the presence of gas in the intestine. Tight clothes may be hard to fit in or may cause discomfort as it takes time for the gas to pass out after the scope.

  • What are some common colonoscopy complications?

    In general complications are rare for colonoscopy. Complications of colonoscopy include sedation related like hypotension, myocardial infarction and stroke. Bleeding, infection and perforation may also occur especially if there is a polypectomy. Other complications include post-polypectomy syndrome which is essentially a form of inflammation that requires some antibiotics to be given after the colonoscopy.