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A colonoscopy is a common medical procedure that allows for detailed examination and treatment of different conditions that involve the large intestine (colon) and occasionally the last part of the small intestine (terminal ileum).

Colorectal cancer screening has been recommended as routine preventative care for all adults since the 1990s. In 2024, colorectal cancers were the third most frequently diagnosed type of cancer.

What is a colonoscopy?

 

During a colonoscopy, a patient is placed under sedation (unless they specifically request otherwise), and a flexible camera and small tools are used to examine the entirety of the large intestine to look for, diagnose, and treat as necessary any encountered abnormalities.

Prior to a colonoscopy, all patients are asked to complete a purge laxative bowel prep to clear the large intestine so that the procedure can be performed safely and effectively. Bowel prep regimens have gradually improved over time and are generally better tolerated than older options used more commonly decades ago.

 

Most patients are asked to split the dose of laxative into two halves, one the evening before the procedure, and one overnight or early the morning of the procedure. While nowadays many different types of bowel prep options are available, I am always grateful for the work my patients put in prior to their procedure. Without a good prep, the procedure literally can’t happen!

The colonoscopy itself is generally the most straightforward part of the procedure. Depending on the specific type of sedation used, most patients are asleep for about 30-45 minutes, during which time the large intestine is examined and your physician works to detect and remove polyps (when done for colorectal cancer screening).

 

Almost all patients complete colonoscopy without any significant symptoms afterwards, but sometimes mild symptoms that generally improve over hours to days can occur. More serious complications from sedation or colonoscopy are possible, but are very uncommon. When performed as an outpatient procedure, patients return home the same day. The colonoscopy itself does not come with post-procedural restrictions. Because almost all patients are sedated for their procedure they are advised to not work or operate a motor vehicle for 24 hours after receiving anesthesia.

Why (and when) do you need a screening colonoscopy?

 

Routine colorectal cancer screening is recommended in all adults at age 45. Patients with a personal history of certain diseases or a family history can discuss earlier screening with a gastroenterologist.

 

Several different options for screening are available with the two most common being stool-based testing (typically tests called FIT or Cologuard) and screening colonoscopy. Unless you have a high risk personal or family history either method is a reasonable choice. Patients with a high risk (or ‘elevated risk’) history should be screened only by colonoscopy, and oftentimes more frequently than the general population.