Skip to content

Colonoscopy vs. Flexible Sigmoidoscopy: Understanding the Key Differences

  • by
Colonoscopy vs. Flexible Sigmoidoscopy: Understanding the Key Differences


Colorectal cancer is a major health problem that needs to be found early and stopped by getting regular tests. Colonoscopy and flexible sigmoidoscopy are two scans that are often used to check for colorectal cancer. Both do pretty much the same thing, but there are some important differences that affect how they are used, how they are done, and how well they work. We will talk about the differences between colonoscopy and flexible sigmoidoscopy in this in-depth guide so that you can make smart choices about your digestive health.

What Are Colonoscopy and Flexible Sigmoidoscopy?

Before we talk about how they are different, let’s talk about what colonoscopy and flexible sigmoidoscopy are and why they are so important for your health.

Colonoscopy: A colonoscopy is a medical procedure that uses a colonoscope, a long, flexible tube with a camera on the end, to look at the whole colon (large intestine). It lets you see the whole colon, which makes it a complete screening tool for intestinal problems, such as cancer.

Flexible Sigmoidoscopy: This method, on the other hand, is mostly used to look at the sigmoid colon and the rectum. A flexible sigmoidoscope, which is shorter than a colonoscope, is used to look at this part of the large intestine.


Scope of Examination

The scope of the examination is one of the main changes between colonoscopy and flexible sigmoidoscopy.

Colonoscopy: A colonoscopy looks at the whole colon, which is about 4 to 6 feet long, as the word suggests. From the cecum to the rectum, it gives a full picture of the colon and lets problems be found all the way along its length.

Flexible Sigmoidoscopy: This type of sigmoidoscopy only looks at the sigmoid colon and the rectum, which aren’t even close to the whole colon. This process only looks at the last 1 to 2 feet of the colon, so it doesn’t give a full picture of the colon.

Procedure Length and Preparation

It’s important to think about how long the process will take and how much work needs to be done ahead of time.

Colonoscopy: This is a more in-depth process that usually takes between 30 minutes and an hour to finish. A tighter diet and a cleansing process may be needed for a few days to get ready for a colonoscopy. A lot of the time, patients have to stick to a liquid diet and use laxatives to really empty their stomachs.

Flexible Sigmoidoscopy: This is a shorter process that most of the time only takes 10 to 20 minutes. Most of the time, getting ready for a sigmoidoscopy is easier than getting ready for a colonoscopy. To get ready for the test, the patient may only need to fast for a short time and use an enema or oral laxative.

Sedation and Discomfort

A big difference is also the comfort during the process.

Colonoscopy: To make sure the patient is comfortable and relaxed, sedation or anesthesia is generally used during a colonoscopy. Most people don’t feel any pain or discomfort during the process, and a lot of them don’t remember it either.

Flexible Sigmoidoscopy: Some people may ask for sedation during flexible sigmoidoscopy, but it is not necessary. The process might be painful at times, but most people can handle it.

Screening Interval

The amount of time between screenings for these treatments varies.

The average chance of getting colorectal cancer is about 1 in 10 people. Starting at age 45, this risk should be checked for every 10 years. If polyps or other problems are found, the time between screenings may need to be changed.

Flexible Sigmoidoscopy: People should get a flexible sigmoidoscopy at least once every five years. It’s important to know, though, that this process only checks a small part of the colon. Because of this, it can be used with other screening methods or after a good stool test as a follow-up.

Detection Capabilities

There are distinct distinctions between the capabilities of each of these methods when it comes to the detection of colorectal abnormalities.

Colonoscopy: Colonoscopy provides a more thorough view of the colon, which enables the detection of polyps, cancers, and other abnormalities throughout the entirety of the colon. Colonoscopy is performed by inserting a thin, lighted tube through the patient’s mouth into the colon. It is an effective method for both early detection and the prevention of diseases.

Although flexible sigmoidoscopy is able to detect abnormalities in the sigmoid colon and rectum, it is possible for it to miss problems that are present in other areas of the colon. This treatment is appropriate for identifying problems within its limited scope; however, it may not be as effective as other procedures in identifying problems within the ascending and transverse colons.

Clinical Utility

How useful these processes are in the real world depends on the person’s health history and risk factors.

  1. Cononoscopy: Because it looks at the whole colon, a colonoscopy is the gold standard for checking for colorectal cancer. People with a normal risk or a family history of colorectal cancer are often told to get it.
  2. Flexible Sigmoidoscopy: This type of biopsy is used in certain cases, like when someone has a positive stool test and needs more tests or when they might not be able to have a full colonoscopy. People who are less likely to get colon cancer should do it.

Cost and Insurance Coverage

Prices and insurance plans may be different for these treatments.

Colonoscopy: Colonoscopy is usually more expensive than flexible sigmoidoscopy. As a recommended preventive test, colonoscopy is covered by a lot of insurance companies.

Flexible Sigmoidoscopy: This type of sigmoidoscopy is often less expensive, but insurance companies may not pay it. You should talk to your insurance company to find out what they cover.


Colonoscopy and flexible sigmoidoscopy are both very important for digestive health, but they are used for different things and have different features. Which one you choose should depend on your personal risk factors, what your doctor suggests, and how comfortable you are with the idea.

Remember that regular colon screenings are important for finding problems early and stopping them before they get worse. Talk to your doctor or nurse if you have questions or worries about which procedure is best for you. In the end, the goal is to protect your colorectal health and lower your chance of colorectal cancer by getting the right tests and getting help early.

Leave a Reply

Your email address will not be published. Required fields are marked *