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 orprecancerous polyps, and to enable the opportunity forbiopsy or the removal of suspectedcolorectal cancer lesions.[4][5]
Colonoscopy is similar tosigmoidoscopy, but surveys the entire colon rather than only the sigmoid colon. A colonoscopy permits a comprehensive examination of the entire colon, which is typically around 1,200 to 1,500 millimeters in length.[6][failed verification]
In contrast, a sigmoidoscopy allows for the examination of only the distal portion of the colon, which spans approximately 600 millimeters.[7][better source needed] 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.[2][need quotation to verify]
Routine use of colonoscopy screening varies globally. In the US, colonoscopy is a commonly recommended and widely utilized screening method for colorectal cancer, often beginning at age 45 or 50, depending on risk factors and guidelines from organizations like the American Cancer Society.[8] However, screening practices differ worldwide. For example, in the European Union, several countries primarily employ fecal occult blood testing (FOBT) or sigmoidoscopy for population-based screening.[9] These variations stem from differences in healthcare systems, policies, and cultural factors. Recent studies[10] have stressed the need for screening strategies and awareness campaigns to combat colorectal cancer - on a global scale.[11][12]
Fecal occult blood is a quick test which can be done to test for microscopic traces of blood in the stool. A positive test is almost always an indication to do a colonoscopy. In most cases the positive result is just due tohemorrhoids; however, it can also be due todiverticulosis, inflammatory bowel disease (Crohn's disease,ulcerative colitis), colon cancer, orpolyps.Colonic polypectomy has become a routine part of colonoscopy, allowing quick and simple removal of polyps during the procedure, without invasive surgery.[17]
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.[18]
Subsequent rescreenings are then scheduled based on the initial results found, with a five- or ten-year recall being common for colonoscopies that produce normal results.[20][21]
Among people who have had an initial colonoscopy that found no polyps, the risk of developing colorectal cancer within five years is extremely low. Therefore, there is no need for those people to have another colonoscopy sooner than five years after the first screening.[22][23]
Some medical societies in the US recommend a screening colonoscopy every ten years beginning at age 50 for adults without increased risk for colorectal cancer.[24] Research shows that the risk of cancer is low for 10 years if a high-quality colonoscopy does not detect cancer, so tests for this purpose are indicated every ten years.[24][25]
Colonoscopy screening is associated with approximately two-thirds fewer deaths due to colorectal cancers on the left side of the colon, and is not associated with a significant reduction in deaths from right-sided disease. It is speculated that colonoscopy might reduce rates of death from colon cancer by detecting some colon polyps and cancers on the left side of the colon early enough that they may be treated, and a smaller number on the right side.[26]
Since polyps often take 10 to 15 years to transform into cancer in someone at average risk of colorectal cancer, guidelines recommend 10 years after a normal screening colonoscopy before the next colonoscopy. (This interval does not apply to people at high risk of colorectal cancer or those who experience symptoms of the disease.)[27][28]
The largerandomizedpragmatic clinical trial NordICC was the first published trial on the use of colonoscopy as a screening test to prevent colorectal cancer, related death, and death from any cause. It included 84,585 healthy men and women aged 55 to 64 years in Poland, Norway, and Sweden, who were randomized to either receive an invitation to undergo a single screening colonoscopy (invited group) or to receive no invitation or screening (usual-care group). Of the 28,220 people in the invited group, 11,843 (42.0%) underwent screening. A total of 15 people who underwent colonoscopy (0.13%) had major bleeding after polyp removal.
None of the participants experienced acolon perforation due to colonoscopy. After 10 years, anintention-to-screen analysis showed a significantrelative risk reduction of 18% in the risk of colorectal cancer (0.98% in the invited group vs. 1.20% in the usual-care group). The analysis showed no significant change in the risk of death from colorectal cancer (0.28% vs. 0.31%) or in the risk of death from any cause (11.03% vs. 11.04%). To prevent one case of colorectal cancer, 455 invitations to colonoscopy were required.[29][30]
As of 2023, the CONFIRM trial, a randomized trial evaluating colonoscopy vs.fecal immunochemical test is currently ongoing.[31]
In 2021, the US spent $43 billion on cancer screening to prevent five cancers, with colonoscopies accounting for 55% of the total.[32] The death rate from colon cancer has been on a linear decline for 40 years, falling by nearly 50 percent from the 1980s (when few were screened) to 2024; however, the increase in screening did not accelerate the decline.[33] Therefore, resources devoted to cancer screening would be better directed toward ensuring widespread access to effective cancer treatment.[34]
TheAmerican Cancer Society issues recommendations on colorectal cancer screening guidelines. These guidelines often change and are updated as new studies and technologies have become available[8]
Many other national organizations also issue such guidance, such as the UK'sNHS[35] and various European agencies,[36] guidance can vary between such agencies.
Electrolyte imbalance caused by bowel preparation solutions is possible, but current bowel cleansing laxatives are formulated to account for electrolyte balance, making this a very rare event.[42]
During colonoscopies, when apolyp is removed (a polypectomy), the risk of complication increases.[43][44] One of the most serious complications ispostpolypectomy coagulation syndrome, occurring in 1 in1000 procedures.[45] It results from a burn injury to the wall of the colon causing abdominal pain, fever, elevated white blood cell count and elevated serumC-reactive protein. Treatment consists of intravenous fluids, antibiotics, and avoiding oral intake of food, water, etc. until symptoms improve. Risk factors include right colon polypectomy, large polyp size (>2 cm), non-polypoid lesions (laterally spreading lesions), and hypertension.[46]
Although rare, infections of the colon are a potential colonoscopy risk. The colon is not asterile environment, and infections can occur during biopsies from what is essentially a 'small shallow cut', enabling bacterial intrusion into lower parts of the colon wall. In cases where the lining of the colon is perforated, bacteria can infiltrate theabdominal cavity.[47]
Minor colonoscopy risks may includenausea,vomiting orallergies to thesedatives that may have been used. If medication is given intravenously, thevein may become irritated, or mildphlebitis may occur.[48]
The colon must be free of solid matter for the test to be performed properly.[49] For one to three days, the patient is required to follow alow fiber or clear-liquid-only diet. Examples of clear fluids areapple juice, chicken and/or beef broth orbouillon,lemon-limesoda, lemonade,sports drink, andwater. It is important that the patient remains hydrated. Sports drinks containelectrolytes which are depleted during the purging of the bowel. Drinks containing fiber such asprune andorange juice should not be consumed, nor should liquidsdyed red, purple, orange, or sometimes brown; however, cola is allowed. In most cases,tea orcoffee taken without milk are allowed.[50][51]
The patient may be asked not to take aspirin or similar products such assalicylate,ibuprofen, etc. for up to ten days before the procedure to avoid the risk of bleeding if a polypectomy is performed during the procedure. A blood test may be performed before the procedure.[54]
During the procedure, the patient is often givensedation intravenously, employing agents such asfentanyl ormidazolam. Although meperidine (Demerol) may be used as an alternative to fentanyl, the concern of seizures has relegated this agent to second choice for sedation behind the combination of fentanyl and midazolam. The average person will receive a combination of these two drugs, usually between 25 and 100μg IV fentanyl and 1–4mg IV midazolam. Sedation practices vary between practitioners and nations; in some clinics in Norway, sedation is rarely administered.[55][56]
The first step is usually adigital rectal examination (DRE), to examine the tone of the analsphincter and to determine if preparation has been adequate. A DRE is also useful in detecting analneoplasms and the clinician may note issues with the prostate gland in men undergoing this procedure.[57] Theendoscope is then passed through theanus up therectum, thecolon (sigmoid, descending, transverse and ascending colon, the cecum), and ultimately theterminal ileum. The endoscope has a movable tip and multiple channels for instrumentation, air, suction and light. The bowel is occasionally insufflated with air to maximize visibility (a procedure that gives the patient the false sensation of needing to take abowel movement). Biopsies are frequently taken forhistology. Additionally in a procedure known aschromoendoscopy, a contrast-dye (such asindigo carmine) may be sprayed through the endoscope onto the bowel wall to help visualize any abnormalities in the mucosal morphology. ACochrane review updated in 2016 found strong evidence that chromoscopy enhances the detection of cancerous tumors in the colon and rectum.[58]
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. These loops often result in discomfort due to stretching of the colon and its associatedmesentery. Manoeuvres to "reduce" or remove the loop include pulling the endoscope backwards while twisting it. Alternatively, body position changes and abdominal support from external hand pressure can often "straighten" the endoscope to allow the scope to move forward. In a minority of patients, looping is often cited as a cause for an incomplete examination. 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.[59]
Polyp is identified.
A sterile solution is injected under the polyp to lift it away from deeper tissues.
The pain associated with the procedure is not caused by the insertion of the scope but rather by the inflation of the colon in order to do the inspection. The scope itself is essentially a long, flexible tube about a centimeter in diameter — that is, as big around as the little finger, which is less than the diameter of an average stool.[60]
The colon has sensors that can tell when there is unexpected gas pushing the colon walls out—which may cause mild discomfort. Usually, total anesthesia or a partialtwilight sedative are used to reduce the patient's awareness of pain or discomfort, or just the unusual sensations of the procedure. Once the colon has been inflated, the doctor inspects it with the scope as it is slowly pulled backward. If any polyps are found they are then cut out for later biopsy.[61]
Colonoscopy can be carried out without any sedation and a number of studies have been performed evaluating colonoscopy outcomes without sedation.[62], though in the US and EU the procedure is usually carried out with some form of sedation.[63]
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. These patients are less likely to live long enough to develop colon cancer.[64]
After Curtiss[65] succeeded in 1956 in coating long, fine glass fibers – in order to reduce information and light losses during image transmission – and bundling them in parallel, the basis for flexible fiber endoscopy was laid. From Von Hirschowiz's report on the first functioning fiber gastroscope[66] in 1957, however, it took another 10 years until the limits of rigid rectoscopy could be regularly overcome with a practical fiberscope. The technical requirements for building a fiber endoscope for colon examinations were extensive. A fiber optic bundle for image transmission, a second bundle for illumination, a control system including wires for bending the instrument tip, tubing for air insufflation and a biopsy channel had to be accommodated in a long, flexible, and thin shaft. The technical pioneering work was carried out by the companies ACMI, Eder Instrument Co., Machida, Olympus, and Sass Wolf. They were supported in this effort by – to name just a few – Overholt (USA), Deyhle, Ottenjann (Germany), and Matsunaga, Niwa, Watanabe, and Yamagata (Japan).
In the 1960s, numerous prototypes were built, which were continually improved (materials, fiber optics, control technology, elasticity, etc.). The first practical fiber sigmoidoscope with a tip that could be bent in two directions and a shaft length of 50 cm was presented by Overholt,[67] in 1967. Niwa[68] Matsunaga[69] and Yamagata[70] reported in 1969 on instruments up to 120 cm long, and Deyhle[71] on an instrument with a tip that could be bent in all directions.
In 1970, Deyhle,[72] Nagasako[73] and Watanabe[74] reported successful examinations extending into the cecum using instruments from Machida and Olympus. Watanabe reached the cecum in 8 of 25 cases, and Deyhle in 22 of 28. He described the insertion technique and documented it on film. The world's first paper on a series of colonoscopies describing the preparation for the examination and the colonoscope insertion technique up to the cecum was published by Deyhle in 1971.[75] Later that same year, the first paper by Wolff and Shinya appeared.[76] During the early 1970s, colonoscopy was introduced in numerous endoscopy centers and specialty practices.
The invention and market for CCD colonoscopy was led by Fujifilm, Olympus, and Hoya in Japan. In 1982, Lawrence Kaplan of the Aspen Medical Group in St. Paul, MN, USA, reported on a series of 100 consecutive colonoscopies and upper endoscopies performed in a freestanding clinic located miles from the nearest hospital to demonstrate the safety and cost-effectiveness of these outpatient procedures. (Personal communication to the Joint Commission on Outpatient Care, May 1983)[full citation needed]
The termscolonoscopy[78][79][80] orcoloscopy[79] are derived from[79] the ancient Greek noun κόλον, same as Englishcolon,[81] and the verb σκοπεῖν,look (in)to,examine.[81] The termcolonoscopy is however ill-constructed,[82] as this form supposes that the first part of the compound consists of a possible rootκολων- orκολον-, with the connecting vowel -o, instead of the rootκόλ- ofκόλον.[82] A compound such asκολωνοειδής,'like a hill',[81] (with the additional -on-) is derived from the ancient Greek word κολώνη orκολωνός'hill'.[81] Similarly, colonoscopy (with the additional -on-) can literally be translated as "examination of the hill",[82] instead of the "examination of the colon".
In English, multiple words exist that are derived from κόλον, such ascolectomy,[79][83][page needed]colocentesis,[79]colopathy,[79] andcolostomy[79] among many others, that actually lack the incorrect additional -on-. A few compound words such ascolonopathy have doublets with -on- inserted.[79][80]
A survey on colonoscopy shows a poor understanding of its protective value and widespread misconceptions. The public has perceptual gaps around the purpose of colonoscopies, the subjective experience of the colonoscopy procedure, and the quantity of bowel preparation needed.[87]
ActorsRyan Reynolds andRob McElhenney have used their social media platform to raise awareness about the importance of colonoscopy as a procedure forcolon cancer screening. They filmed their own colonoscopies as part of a campaign called "Lead From Behind",[88][89] demonstrating that the procedure can be both easy and lifesaving.[90][91]
^"Colonoscopy".The American Heritage Medical Dictionary. Houghton Mifflin Company.Archived from the original on 12 May 2021. Retrieved28 October 2012 – via TheFreeDictionary.
^"Colonoscopy - NIDDK".National Institute of Diabetes and Digestive and Kidney Diseases.Archived from the original on 3 May 2022. Retrieved10 November 2023.
^Rex DK, Bond JH, Winawer S, Levin TR, Burt RW, Johnson DA, et al. (June 2002). "Quality in the technical performance of colonoscopy and the continuous quality improvement process for colonoscopy: recommendations of the U.S. Multi-Society Task Force on Colorectal Cancer".The American Journal of Gastroenterology.97 (6):1296–1308.doi:10.1111/j.1572-0241.2002.05812.x.PMID12094842.S2CID26250449.
^Rex DK, Boland CR, Dominitz JA, Giardiello FM, Johnson DA, Kaltenbach T, et al. (July 2017). "Colorectal Cancer Screening: Recommendations for Physicians and Patients from the U.S. Multi-Society Task Force on Colorectal Cancer".The American Journal of Gastroenterology.112 (7). Ovid Technologies (Wolters Kluwer Health):1016–1030.doi:10.1038/ajg.2017.174.PMID28555630.S2CID6808521.
^Bretthauer M, Løberg M, Wieszczy P, Kalager M, Emilsson L, Garborg K, et al. (October 2022). "Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death".The New England Journal of Medicine.387 (17):1547–1556.doi:10.1056/NEJMoa2208375.hdl:10852/101829.PMID36214590.S2CID252778114.
^Clinical trial numberNCT00883792 for "The Northern-European Initiative on Colorectal Cancer (NordICC)" atClinicalTrials.gov
^Halpern MT, Liu B, Lowy DR, Gupta S, Croswell JM, Doria-Rose VP (2024). "The Annual Cost of Cancer Screening in the United States".Annals of Internal Medicine.177 (9):1170–1178.doi:10.7326/M24-0375.PMID39102723.
^Welch HG (2024). "Dollars and Sense: The Cost of Cancer Screening in the United States".Annals of Internal Medicine.177 (9):1275–1276.doi:10.7326/M24-0887.PMID39102720.
^Smith G, D'Cruz JR, Rondeau B, Goldman J (2023),"General Anesthesia for Surgeons",StatPearls, Treasure Island (FL): StatPearls Publishing,PMID29630251,archived from the original on 26 March 2023, retrieved10 November 2023
^Bretthauer M, Hoff G, Severinsen H, Erga J, Sauar J, Huppertz-Hauss G (May 2004). "[Systematic quality control programme for colonoscopy in an endoscopy centre in Norway]".Tidsskrift for den Norske Laegeforening (in Norwegian).124 (10):1402–1405.PMID15195182.
^Lichtenstein GR, Park PD, Long WB, Ginsberg GG, Kochman ML (January 1999). "Use of a push enteroscope improves ability to perform total colonoscopy in previously unsuccessful attempts at colonoscopy in adult patients".The American Journal of Gastroenterology.94 (1):187–190.doi:10.1111/j.1572-0241.1999.00794.x.PMID9934753.S2CID24536782.Note:Single use PDF copy provided free byBlackwell Publishing for purposes of Wikipedia content enrichment.
^Zhang K, Yuan Q, Zhu S, Xu D, An Z (April 2018). "Is Unsedated Colonoscopy Gaining Ground Over Sedated Colonoscopy?".Journal of the National Medical Association.110 (2):143–148.doi:10.1016/j.jnma.2016.12.003.PMID29580447.
^Curtiss LE, Hirschowitz BI, Peters CW (1956). "A long fiberscope for internal medical examinations".J. Am. Opt. Soc.46: 1030.
^Hirschowitz BI, Curtiss LE, Peters CW, Polland HM (16 May 1957). "Demonstration of a new gastroscope, the "fiberscope"".Ann. Meeting Am. Gastroscop. Soc. Colorado Springs, USA.
^Niwa H, Utsumi Y, Kaneko E, et al. (1969). "Clinical application of colonofiberscope (Japanese)".Gastroenterol. Endosc.11:163–173.
^Matsunage F, Mashima A, Uchino C, et al. (1969). "New large fiberscope (second report) (Japanese)".Gastroenterol. Endosc.11: 219.
^Yamagata K, Miyura K, Watanabe A (1969). "Clinical applications of the large fiberscope Type VII (Japanese)".Gastroenterol. Endosc.11: 219.
^Deyhle P, Ottenjann R, Paul F (1969). "Die proximale peranale coloskopie".73. Tagung der Nordwestdeutschen Gesellschaft für Innere Medizin. Bremen: 32.
^Deyhle P (1970). "Fibercolonoscopy".EEOC Congress. Munich: cited in Classen, M.: Progress Report. Fiberendoscopy of the Intestines. Gut 12,330–338, April 1971.
^Nagasako K, Takemoto T, Kondo T (1970). "The insertion of fibercolonoscop into the caecum and direct observation of the ileocaecal valve".Endoscopy.2:121–126.doi:10.1055/s-0028-1098446.
^Watanabe H, Narasaka T, Uezu J, et al. (1970). "An improved fibercolonoscope and its application to colonic diseases".2nd World Congress of Ganstroint. Endoscopy, Cited in Classen, M.: Progress Report. Fiberendoscopy of the Intestines. Gut 12, 330-338, April 1971. Rome and Kopenhangen.
^abcdLiddell HG, Scott R (1940).A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with the assistance of. Roderick McKenzie. Oxford: Clarendon Press.
^abcAnastassiades CP, Cremonini F, Hadjinicolaou D (2008). "Colonoscopy and colonography: back to the roots".European Review for Medical and Pharmacological Sciences.12 (6):345–347.PMID19146195.
^Foster FD (1891–1893).An illustrated medical dictionary. Being a dictionary of the technical terms used by writers on medicine and the collateral sciences, in the Latin, English, French, and German languages. New York: D. Appleton and Company.
^Selby JV (September 2000). "Explaining recent declines in colorectal cancer incidence: was it the sigmoidoscope?".Am J Med.109 (4):332–4.doi:10.1016/s0002-9343(00)00540-4.PMID10996587.
^Gilbert RE (2014). "The politics of presidential illness. Ronald Reagan and the Iran-Contra Scandal".Politics Life Sci.33 (2):58–76.doi:10.2990/33_2_58.PMID25901884.S2CID41674696.
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