Editing Colonoscopy (section)

==Technique==

===Preparation===
[[File:polyethylene glycol container.jpg|thumb|alt=A container of PEG (polyethylene glycol) with electrolyte used to clean out the intestines before certain bowel exam procedures such as colonoscopy.|A container of PEG ([[macrogol|polyethylene glycol or macrogol]]) with electrolyte used to clean out the [[intestines]] before certain [[bowel]] exam procedures such as a colonoscopy.]]

The colon must be free of solid matter for the test to be performed properly.<ref name="pmid25239068">{{cite journal | vauthors = Johnson DA, Barkun AN, Cohen LB, Dominitz JA, Kaltenbach T, Martel M, Robertson DJ, Boland CR, Giardello FM, Lieberman DA, Levin TR, Rex DK | title = Optimizing adequacy of bowel cleansing for colonoscopy: recommendations from the US multi-society task force on colorectal cancer | journal = Gastroenterology | volume = 147 | issue = 4 | pages = 903–924 | date = October 2014 | pmid = 25239068 | doi = 10.1053/j.gastro.2014.07.002 | publisher = Elsevier BV | doi-access = free }}</ref> For one to three days, the patient is required to follow a [[Low-fiber diet|low fiber]] or clear-liquid-only diet. Examples of clear fluids are [[apple juice]], chicken and/or beef broth or [[Bouillon (broth)|bouillon]], [[lemon-lime]] [[Soft drink|soda]], lemonade, [[sports drink]], and [[Drinking water|water]]. It is important that the patient remains hydrated. Sports drinks contain [[electrolyte]]s which are depleted during the purging of the bowel. Drinks containing fiber such as [[prune]] and [[orange juice]] should not be consumed, nor should liquids [[Food colouring|dyed]] red, purple, orange, or sometimes brown; however, cola is allowed. In most cases, [[tea]] or [[coffee]] taken without milk are allowed.<ref>{{cite web |title=Preparing for Your Colonoscopy: Types of Kits & Instructions |url=https://my.clevelandclinic.org/health/treatments/22657-colonoscopy-bowel-preparation |access-date=9 November 2023 |website=Cleveland Clinic |archive-date=9 November 2023 |archive-url=https://web.archive.org/web/20231109202335/https://my.clevelandclinic.org/health/treatments/22657-colonoscopy-bowel-preparation |url-status=live }}</ref><ref>{{cite journal | vauthors = Parra-Blanco A, Nicolas-Perez D, Gimeno-Garcia A, Grosso B, Jimenez A, Ortega J, Quintero E | title = The timing of bowel preparation before colonoscopy determines the quality of cleansing, and is a significant factor contributing to the detection of flat lesions: a randomized study | journal = World Journal of Gastroenterology | volume = 12 | issue = 38 | pages = 6161–6166 | date = October 2006 | pmid = 17036388 | pmc = 4088110 | doi = 10.3748/wjg.v12.i38.6161 | doi-access = free }}</ref>

The day before the colonoscopy (or [[colorectal surgery]]), the patient is either given a [[laxative]] preparation (such as [[bisacodyl]], [[phospho soda]], [[sodium picosulfate]], or [[sodium phosphate]] and/or [[magnesium citrate]]) and large quantities of fluid, or [[whole bowel irrigation]] is performed using a solution of [[polyethylene glycol]] and [[electrolytes]].<ref>{{cite journal | vauthors = Hung SY, Chen HC, Chen WT | title = A Randomized Trial Comparing the Bowel Cleansing Efficacy of Sodium Picosulfate/Magnesium Citrate and Polyethylene Glycol/Bisacodyl (The Bowklean Study) | journal = Scientific Reports | volume = 10 | issue = 1 | pages = 5604 | date = March 2020 | pmid = 32221332 | pmc = 7101403 | doi = 10.1038/s41598-020-62120-w | bibcode = 2020NatSR..10.5604H }}</ref><ref>{{cite journal | vauthors = Kumar AS, Kelleher DC, Sigle GW | title = Bowel Preparation before Elective Surgery | journal = Clinics in Colon and Rectal Surgery | volume = 26 | issue = 3 | pages = 146–152 | date = September 2013 | pmid = 24436665 | pmc = 3747288 | doi = 10.1055/s-0033-1351129 }}</ref>

The patient may be asked not to take aspirin or similar products such as [[salicylate]], [[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.<ref>{{cite web|url=http://www.pamf.org/gastroenterology/ColyteColon.pdf |title=Colyte/Trilyte Colonoscopy Preparation |access-date=12 June 2007 |date=June 2006 |publisher=Palo Alto Medical Foundation |url-status=dead |archive-url=https://web.archive.org/web/20070414032341/http://www.pamf.org/gastroenterology/ColyteColon.pdf |archive-date=14 April 2007 }}</ref>

===Procedure===
[[File:Diagram showing a colonoscopy CRUK 060.svg|thumb|left|Schematic overview of colonoscopy procedure]]

During the procedure, the patient is often given [[sedation]] intravenously, employing agents such as [[fentanyl]] or [[midazolam]]. 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 100{{nbsp}}μg IV fentanyl and 1–4{{nbsp}}mg IV midazolam. Sedation practices vary between practitioners and nations; in some clinics in Norway, sedation is rarely administered.<ref>{{cite journal | vauthors = Bretthauer M, Hoff G, Severinsen H, Erga J, Sauar J, Huppertz-Hauss G | title = [Systematic quality control programme for colonoscopy in an endoscopy centre in Norway] | language = no | journal = Tidsskrift for den Norske Laegeforening | volume = 124 | issue = 10 | pages = 1402–1405 | date = May 2004 | pmid = 15195182 }}</ref><ref>{{cite journal | vauthors = Dossa F, Dubé C, Tinmouth J, Sorvari A, Rabeneck L, McCurdy BR, Dominitz JA, Baxter NN | title = Practice recommendations for the use of sedation in routine hospital-based colonoscopy | journal = BMJ Open Gastroenterology | volume = 7 | issue = 1 | pages = e000348 | date = 16 February 2020 | pmid = 32128226 | pmc = 7039579 | doi = 10.1136/bmjgast-2019-000348 }}</ref>

The first step is usually a [[digital rectal examination]] (DRE), to examine the tone of the anal [[sphincter]] and to determine if preparation has been adequate. A DRE is also useful in detecting anal [[neoplasm]]s and the clinician may note issues with the prostate gland in men undergoing this procedure.<ref>{{cite journal | vauthors = Farooq O, Farooq A, Ghosh S, Qadri R, Steed T, Quinton M, Usmani N | title = The Digital Divide: A Retrospective Survey of Digital Rectal Examinations during the Workup of Rectal Cancers | journal = Healthcare | volume = 9 | issue = 7 | pages = 855 | date = July 2021 | pmid = 34356233 | pmc = 8306048 | doi = 10.3390/healthcare9070855 | doi-access = free }}</ref> The [[endoscopy|endoscope]] is then passed through the [[Human anus|anus]] up the [[rectum]], the [[Colon (anatomy)|colon]] (sigmoid, descending, transverse and ascending colon, the cecum), and ultimately the [[ileum|terminal 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 a [[bowel movement]]). Biopsies are frequently taken for [[histology]]. 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.<ref>{{cite journal | vauthors = Brown SR, Baraza W, Din S, Riley S | title = Chromoscopy versus conventional endoscopy for the detection of polyps in the colon and rectum | journal = The Cochrane Database of Systematic Reviews | volume = 2016 | issue = 4 | pages = CD006439 | date = April 2016 | pmid = 27056645 | pmc = 8749964 | doi = 10.1002/14651858.CD006439.pub4 }}</ref>

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 associated [[mesentery]]. 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.<ref>{{cite journal | vauthors = Lichtenstein GR, Park PD, Long WB, Ginsberg GG, Kochman ML | title = Use of a push enteroscope improves ability to perform total colonoscopy in previously unsuccessful attempts at colonoscopy in adult patients | journal = The American Journal of Gastroenterology | volume = 94 | issue = 1 | pages = 187–190 | date = January 1999 | pmid = 9934753 | doi = 10.1111/j.1572-0241.1999.00794.x | s2cid = 24536782 }} ''Note:Single use PDF copy provided free by [[Blackwell Publishing]] for purposes of Wikipedia content enrichment.''</ref>

<gallery>
Image:Endomucosal resection 1.jpg|Polyp is identified.
Image:Endomucosal resection 2.jpg|A sterile solution is injected under the polyp to lift it away from deeper tissues.
Image:Endomucosal resection 3.jpg|A portion of the polyp is now removed.
Image:Endomucosal resection 4.jpg|The polyp is fully removed.
</gallery>

===Patient comfort and pain management===
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.<ref>{{cite journal | vauthors = Ekkelenkamp VE, Dowler K, Valori RM, Dunckley P | title = Patient comfort and quality in colonoscopy | journal = World Journal of Gastroenterology | volume = 19 | issue = 15 | pages = 2355–2361 | date = April 2013 | pmid = 23613629 | pmc = 3631987 | doi = 10.3748/wjg.v19.i15.2355 | doi-access = free }}</ref>

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 partial [[twilight anesthesia|twilight 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.<ref>{{cite journal |last1=Brown |first1=Shaun |last2=Whitlow |first2=Charles B. |date=1 March 2017 |title=Patient comfort during colonoscopy |url=https://www.sciencedirect.com/science/article/pii/S1043148916300549 |journal=Seminars in Colon and Rectal Surgery |series=SI: Advanced Endoscopy Outline |volume=28 |issue=1 |pages=1–3 |doi=10.1053/j.scrs.2016.11.004 |issn=1043-1489 |url-access=subscription |access-date=10 November 2023 |archive-date=27 February 2024 |archive-url=https://web.archive.org/web/20240227031615/https://www.sciencedirect.com/science/article/abs/pii/S1043148916300549 |url-status=live }}</ref>

Colonoscopy can be carried out without any sedation and a number of studies have been performed evaluating colonoscopy outcomes without sedation.<ref>{{cite journal | vauthors = Zhang K, Yuan Q, Zhu S, Xu D, An Z | title = Is Unsedated Colonoscopy Gaining Ground Over Sedated Colonoscopy? | journal = Journal of the National Medical Association | volume = 110 | issue = 2 | pages = 143–148 | date = April 2018 | pmid = 29580447 | doi = 10.1016/j.jnma.2016.12.003 }}</ref> Though in the US and EU the procedure is usually carried out with some form of sedation.<ref>{{cite journal | url=https://www.giejournal.org/article/S0016-5107(99)70381-0/fulltext | doi=10.1016/S0016-5107(99)70381-0 | title=Patients willing to try colonoscopy without sedation: Associated clinical factors and results of a randomized controlled trial | date=1999 | journal=Gastrointestinal Endoscopy | volume=49 | issue=5 | pages=554–559 | pmid=10228251 | vauthors = Rex DK, Imperiale TF, Portish V }}</ref>