Colonoscopy is an examination of the large intestine (colon) using a special endoscope (colonoscope). This is a thin, flexible, tube-shaped instrument with an integrated light source. In contrast to sigmoidoscopy, the examination of the sigmoid colon (colon sigmoideum; last section of the large intestine/between the descending colon (“descending colon”) and the rectum), colonoscopy examines the entire colon (large intestine) up to and including the caecum (appendix, which is the most proximal section of the large intestine) or screening colonoscopy is used for the early detection of pathological (pathological) changes in the intestinal mucosa (e.g. polyps, adenomas): patients with statutory health insurance are entitled to two colonoscopies; men from the age of 50 and women from the age of 55. The minimum interval must be 10 years. Note: A 50-year-old man with high genetic risk, an unhealthy lifestyle and no screening colonoscopy has an estimated absolute risk of 13.4% of developing colorectal cancer within the next 30 years. In women with this constellation, the risk is 10.6%.
Indications (areas of application)
- Blood in the stool (hematochezia or melena (tarry stools)).
- Positive immunological stool test: This test is used to detect occult blood (small amounts of non-visible blood) in the stool.
- Change in bowel habits such as persistent diarrhea (diarrhea) or constipation (constipation).
- Persistent pain in the abdominal area
- Chronic intestinal diseases such as.
- Crohn’s disease
- Ulcerative colitis (CU):
- Control colonoscopy to record the pattern of affection no later than 8 years after the onset of symptoms.
- Surveillance colonoscopies should be performed 1-2 years after initial manifestation for extensive CU beginning at 8 years and for left-sided or distal CU beginning at 15 years.
- Suspected colorectal polyps/adenomas – 70-80% of all colorectal polyps are adenomas, which are neoplasms (new formations) that carry malignant potency, meaning they can degenerate malignantly
- Suspicion of colon cancer (colon carcinoma).
- In symptom-free patients for colorectal cancer screening as part of preventive examinations from the age of 50 in men and 55 in women.
- Patients with genetic (familial) predisposition to colorectal cancer:
- HNPCC (hereditary non-polyposis colorectal cancer; hereditary colorectal cancer without polyposis, also known as “Lynch syndrome“) – initiation of colorectal cancer screening including colonoscopy from the age of 25.
- FAP (familial adenomatous polyposis; obligate precancerous disease / later cancer significantly likely; degeneration begins from the fifteenth year of life!) – Start of colorectal cancer screening including colonoscopy already from the age of 10.
- First-degree relatives of patients with colorectal cancer should be completely colonoscoped for the first time at an age 10 years before the age of onset of carcinoma in the index patient, at the latest at the age of 40-45 years.Colonoscopy should be repeated at least every 10 years* if the colon is free of polyps in the initial colonoscopy.
- First-degree relatives of index patients in whom adenomas were detected before the age of 50 years should be colonoscoped 10 years before the age at the time of detection of the adenoma. Colonoscopy should be repeated at least every 10 years* if the colon is free of polyps in the initial colonoscopy.
* The American guideline recommends a 5-year interval,
Before the examination
It is important to prepare the patient well: Three days before colonoscopy, patients should avoid foods with seeds, grains, and fruit peels (cereals, whole-grain bread; poppy seeds, nuts, kiwi, tomatoes, grapes). This is because, despite bowel cleansing, seeds and peels could stick to the bowel wall and impair the view or block the instruments during endoscopy.The day before the examination must be drained – the cleaner the bowel, the more the gastroenterologist will see. The German Society for Digestive and Metabolic Diseases (DGVS) published a position paper on bowel cleansing before colonoscopy in 2007.This generally gives preference to the splitting dosage (= bowel cleansing spread over two days; first liter the evening before, the second liter the next morning/approx. 4 h before the examination) over the one-part regime and points out the superiority of a PEG solution (polyethylene glycol (PEG) and sodium phosphate (NaP) solutions; PEG solution plus vitamin C, drinking quantity 2 liters). Afterwards, only drinking is allowed.A metaanlysis confirms that this approach contributes to better cleaning results and higher patient satisfaction. In addition, another study proves that the splitting dosage puts less strain on the microbiome (the totality of all microorganisms colonizing the human gut). Likewise, splitting the colonoscopy solution into two doses significantly increases the adenoma detection rate (rate of adenomas found). Platelet aggregation inhibitors (antiplatelets) or oral anticoagulants (anticoagulants) do not need to be discontinued during a diagnostic colonoscopy. However, if a polypectomy (removal of polyps) is required, a second procedure is necessary after a seven-day break in therapy.
The procedure
Colonoscopy is both a diagnostic and treatment procedure. Special endoscopes with light, optical and working channels are used to see and evaluate the entire large intestine (colon). The tip of these flexible tubes can be angled in all directions so that almost all areas of the colon (large intestine) can be viewed up to the caecum (appendix, which is the most proximal section of the colon). This examination also has the advantage that small tissue samples can be taken from suspicious areas of the intestinal mucosa, which are then available for fine tissue examination (histology). Today’s technical standards include high-definition resolution as well as real and virtual chromoendoscopy. In chromoendoscopy, dyes such as indigo carmine or methylene blue are sprayed directly onto the suspect (suspicious) tissue area via the endoscope. This allows changes in the mucosa to be visualized with greater contrast; flat and sunken changes are also easier to identify. The examination is performed on an outpatient basis and under analgosedation (painless twilight sleep) in a comfortable lying position. A colonoscopy usually takes no longer than 20 to 30 minutes.
Possible complications
- More severe bleeding (e.g., after polyp removal or tissue sampling) (0.2-0.3%)
- Injury or perforation (puncture) of the intestinal wall with injury to adjacent organs (e.g., spleen) (0.01-0.1%)
- Injury to the sphincter (sphincter muscle) with the endoscope (very rare).
- Injuries to the intestinal wall that lead to peritonitis (inflammation of the peritoneum) only after a few days.
- Accumulation of gases in the intestine possible, which can lead to colicky pain.
- Hypersensitivity or allergies (e.g., anesthetics/anesthetics, dyes, medications, etc.) may temporarily cause the following symptoms: Swelling, rash, itching, sneezing, watery eyes, dizziness or vomiting.
- Infections after which severe life-threatening complications concerning heart, circulation, respiration, etc. occur are very rare (1.6 patients have severe infections per 1,000 examinations). Similarly, permanent damage (e.g., paralysis) and life-threatening complications (e.g., sepsis/blood poisoning) are very rare after infections.
Through a questionnaire survey, complications during and within 4 weeks after colonoscopy were recorded. 5,252 participants who completed the questionnaire were included in the study. There were 10 physician-confirmed bleeds and 2 perforations during colonoscopy and 6 bleeds and 2 perforations in the 4 weeks after colonoscopy (= complication rate of 20/5 252 = 0.38%). Note: Patients older than 75 years have a significantly increased risk of complications following colonoscopy. Elderly patients required hospitalization more than 2.3 times as often as younger patients in the first 30 days after colonoscopy in a study of 38,069 patients; all comorbidities (concomitant diseases) and associated factors were considered: The rate of post-colonoscopy bleeding was increased 3-fold, that of bowel perforation doubled, and that of infection quadrupled; smokers had a tripled risk of complications.The 30-day mortality rate (death rate) was 0.1% among younger patients and 0.2% among older patients. Additional notes
- Stage T1 colon carcinomas are detected by the endoscopist with the naked eye in a screening after a positive immunologic stool test in only 39% of cases. This creates a risk of inappropriate resection techniques (procedures of surgical removal), such as the use of piecemeal rather than en bloc ablation of the tumor (piecemeal ablation rather than ablation in its entirety).
- Patients who underwent surgery for colorectal carcinoma had recurrent interval colon cancer (metachronous colon carcinoma) in 3% of cases. Possible iatrogenic tumor seeding by colonoscopy through the working channel was demonstrated in an analysis of primary and secondary tumors.
- An important quality parameter for screening colonoscopy is the adenoma detection rate (ADR; proportion of screening colonoscopies performed by a physician that result in the detection of at least one adenoma), which should be at least 30% in men and at least 20% in women in Western countries.
- Adenoma detection rates are significantly increased when water rather than air is insufflated during colonoscopy: Overall ADR in the water insufflation (WI) group was 18.3% and in the air insufflation group was 13.4% (RR 1.45, 95% CI 1.20-1.75; p < 0.001). Furthermore, more small (< 10 mm), flat, and tubular adenomas were also found in the WI group (better detection rate under WI); likewise, patient satisfaction was higher in the WI group (94.5% versus 91.5%).
- After negative screening colonoscopy (screening colonoscopy), the incidence of colon cancer in the tenth year after colonoscopy is about half, and colorectal cancer mortality is even 88% lower than in unscreened patients of the same age.
- Even a single sigmoidoscopy (common colorectal cancer screening in the UK) between the ages of 55 and 64 can reduce the risk of colon cancer even after 17 years (per-protocol analysis: reduction in colon cancer rate 35%; distal tumors: reduction 56%).
- Results of a second examination: frequency of lesion occurrence (lesions/changes) after initial colonoscopy in relation to the duration of the past years after the first colonoscopy:
- 1-5 years: 20.7% of all examined had lesions.
- 5-10 years: 23 %
- > 10 years: 21.9
Results when considering the clinically much more relevant advanced precursors:
- 1-5 years: 2.8% of all examined had lesions
- 5-10 years: 3.2 %
- > 10 years: 7
CONCLUSION: In a follow-up colonoscopy in the first ten years after an inconspicuous colonoscopy, relevant findings are found only very rarely. However, in special cases, such as an increased risk due to a family history, a follow-up examination should be performed earlier.
Benefit
Colonoscopy provides you with an effective screening test for the early detection of:
- Colorectal cancer (colon carcinoma)
- Colon polyps/adenomas
- Diverticulitis – diverticulosis is the term used to describe protrusions of the intestinal wall. If these protrusions become inflamed, one speaks of diverticulitis.
- Chronic inflammatory bowel disease
It offers you the opportunity for early detection of pathological changes in the mucosa of the intestine, such as colon polyps / adenomas or colon cancer. The initially benign (benign) changes can be detected and removed in time. In this way, the development of cancer can be prevented. Colonoscopy is one of the recommended screening examinations and should be repeated at regular intervals (see below “Screening plan for men” or “Screening plan for women”.
