[2][3] The purpose of a colonoscopy is to provide a visual diagnosis via inspection of the internal lining of the colon wall, which may include identifying issues such as ulceration or precancerous polyps, and to enable the opportunity for biopsy or the removal of suspected colorectal cancer lesions.

[7] This distinction is medically significant because the benefits of colonoscopy in terms of improving cancer survival have primarily been associated with the detection of lesions in the distal portion of the colon.

For example, in the European Union, several countries primarily employ fecal occult blood testing (FOBT) or sigmoidoscopy for population-based screening.

Recent studies[11] have stressed the need for screening strategies and awareness campaigns to combat colorectal cancer - on a global scale.

Colonic polypectomy has become a routine part of colonoscopy, allowing quick and simple removal of polyps during the procedure, without invasive surgery.

[18] With regard to blood in the stool either visible or occult, it is worthy of note, that occasional rectal bleeding may have multiple non-serious potential causes.

[23][24] Some medical societies in the US recommend a screening colonoscopy every 10 years beginning at age 50 for adults without increased risk for colorectal cancer.

Typically, the reasons are that the bowel prep done to facilitate the examination acts to reduce the potential for contamination, resulting in a higher likelihood of conservative management.

In addition, detection at the time allows the physician to deploy strategies to seal the colon, or mark it should the patient require surgery.

Examples of clear fluids are apple juice, chicken and/or beef broth or bouillon, lemon-lime soda, lemonade, sports drink, and water.

[53][54] The procedure may involve both a pill-form laxative and a bowel irrigation preparation with the polyethylene glycol powder dissolved into any clear liquid, such as a sports drink that contains electrolytes.

A DRE is also useful in detecting anal neoplasms and the clinician may note issues with the prostate gland in men undergoing this procedure.

Additionally in a procedure known as chromoendoscopy, a contrast-dye (such as indigo carmine) may be sprayed through the endoscope onto the bowel wall to help visualize any abnormalities in the mucosal morphology.

A Cochrane review updated in 2016 found strong evidence that chromoscopy enhances the detection of cancerous tumors in the colon and rectum.

[59] In most experienced hands, the endoscope is advanced to the junction of where the colon and small bowel join up (cecum) in under 10 minutes in 95% of cases.

Due to tight turns and redundancy in areas of the colon that are not "fixed", loops may form in which advancement of the endoscope creates a "bowing" effect that causes the tip to actually retract.

Alternatively, body position changes and abdominal support from external hand pressure can often "straighten" the endoscope to allow the scope to move forward.

Usage of alternative instruments leading to completion of the examination has been investigated, including use of pediatric colonoscope, push enteroscope and upper GI endoscope variants.

[62] The colon is wrinkled and corrugated, somewhat like an accordion or a clothes-dryer exhaust tube, which gives it the large surface area needed for nutrition and water absorption.

Usually, total anesthesia or a partial twilight sedative are used to reduce the patient's awareness of pain or discomfort, or just the unusual sensations of the procedure.

[1] Researchers have found that older patients with three or more significant health problems (i.e., dementia or heart failure) had higher rates of repeat colonoscopies without medical indications.

[67] Their invention, in 1969 in Japan, was a significant advance over the barium enema and the flexible sigmoidoscope because it allowed for the visualization and removal of polyps from the entire colon.

Wolff and Shinya advocated for their invention and published much of the early evidence needed to overcome skepticism about the device's safety and efficacy.

[69][better source needed] The terms colonoscopy[70][71][72] or coloscopy[71] are derived from[71] the ancient Greek noun κόλον, same as English colon,[73] and the verb σκοπεῖν, look (in)to, examine.

In English, multiple words exist that are derived from κόλον, such as colectomy,[71][75] colocentesis,[71] colopathy,[71] and colostomy[71] among many others, that actually lack the incorrect additional -on-.

[79] Actors Ryan Reynolds and Rob McElhenney have used their social media platform to raise awareness about the importance of colonoscopy as a procedure for colon cancer screening.