Colon intestine - function, pain and problems

Colon intestine - function, pain and problems

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We call the colon the main part of the large intestine between the appendix and rectum. These include the ascending colon (ascending colon), the right bowel bow (Flexura coli dextra), the transverse colon (transverse colon), the left bowel bow (Flexura coli sinistra), the descending colon (descending colon), and the S-shaped colon (Colon sigmoideum). This section of the large intestine is followed by the rectum and ultimately the anus.

Neighbor of liver and kidney

The neighboring organs of the individual parts of the colon are: at the right bend at the level of the 9th rib the liver at the top, at the back the right kidney, at the transverse colon the liver, pancreas, stomach and gall bladder, at the left bend at the level of the 10th rib at the top Spleen and behind the left kidney. Small intestine loops are to the right of the descending colon. The S-shaped colon is over the left ureter.

The Grimms gut is about 1 meter long, and its wall forms bulges that are visible from the outside, the Haustrien. He also has plicae semilunares coli, which are internal folds and three stripes of longitudinal muscles that we can also see from the outside. The outer wall layer contains protuberances filled with fat (appendices epiploicae).

Mucosa refers to the mucous membrane. It consists of indentations, microvilli and goblet cells that produce mucus that makes the stool glide, as well as lymphatic membranes.

Three layers

The colon is divided into three layers, the epithelial layer, the connective tissue layer and the muscle layer. Then there is the submucosa, a layer of connective tissue with blood and lymphatic vessels and nerves.

The wall of the colon

The intestinal wall consists of the musculari, the dances and the peritoneum. The inner circular muscles and the outer longitudinal muscles lie in the muscularis. The colon wall is divided by three ligaments, the dances, which serve to shorten the colon. The peritoneum (serosa) consists of connective tissue that envelops the intestine.

Role of the colon

The bowel thickens the chyme, its mucus promotes the lubricity of the ingested food, and it prepares the indigestible parts of the food for bowel movements.

The so-called Bauhin valve releases portions of the meal into the appendix. Two nerve networks drive wave-like contractions of the colon muscles. Two different movements serve this purpose, namely mixed and transport movements. With mixed movements, contraction passes through the ring muscles and thus mixes the contents of the intestine. This allows the nutrients to be absorbed. Such mixing movements take place approximately 15 times per minute. The transport movements are far less frequent, they only occur two to three times a day, so we have to go to the toilet to empty the chair.

The most important task of the colon, however, is to recover water and electrolytes, in total it is one liter of fluid per day. The bacteria in the colon convert food components, break down vegetable fibers and thus produce vitamin K and vitamin B 7.


Many diseases can develop in the colon, from intestinal inflammation to colon cancer. These diseases include: Colon irritable, megacolon, colitis, ulcerative colitis, and the common intestinal polyps. If not removed, the latter can develop into intestinal tumors. The most common complaint in the colon is diarrhea.

Crohn's disease and ulcerative colitis

Crohn's disease and ulcerative colitis are the most common chronic diseases of the intestine, which are chronic inflammations of the intestine. An important difference is the extent of the illness. In Crohn's disease, the entire gastrointestinal tract is affected, whereas ulcerative colitis only rages in the large intestine.

Ulcerative colitis

Ulcerative colitis affects the upper layers of the mucous membrane on the intestinal wall. Slightly bleeding ulcers form there. The disease usually starts in the rectum, spreads in the large intestine and moves towards the appendix. In every fourth affected person, the inflammation affects the entire colon.

Most sufferers experience episodes of the disease, between which there are longer periods without symptoms. However, one in ten has no periods without complaints. In every twentieth the inflammation takes on an extreme form: very severe diarrhea, high fever and, associated with this, a high loss of water lead to circulatory shock - ulcerative colitis can even lead to death in these people.

Bloody diarrhea

In the acute phases of ulcerative colitis, sufferers suffer from diarrhea, the faeces mix with blood and mucus and torment the patient up to 30 times a day. Each time they also have stomach cramps, which are extremely painful. Sometimes there is a fever.

The symptoms rarely show up outside the intestine, as inflammation in joints, on the eyes and on the skin. If only the rectum is affected, diarrhea, which is as slimy as it is bloody, is the safest feature.

Danger: intestinal breakthrough

Dangerous complications of this disease are possible intestinal paralysis. If the inflammation severely damages the intestinal wall, the muscles there relax, the intestine cannot transport the food supplied and it expands. High fever occurs and inflammation of the peritoneum threatens. If the doctors do not operate immediately, an intestinal breakthrough is imminent - and it can cost life.

In addition, the risk of colon cancer is greatly increased: chronic ulcerative colitis very often degenerates after ten years.

Crohn's disease

Crohn's disease is characterized by:

  1. Regular diarrhea. These are slimy, but mostly without blood. However, ulcerative colitis is almost always accompanied by bloody stools.
  2. Abdominal pain occurring in episodes, usually in the right lower abdomen. Here there is a risk of confusing the disease with an inflamed appendix. Ulcerative colitis also leads to abdominal pain, but this occurs spasmodically and immediately before bowel movements.
  3. Weight loss and mild fever. But that is not a must.

As with all serious illnesses, panic is just as bad a guide as carelessness. If you suffer from severe diarrhea that lasts more than three days, combined with a mild fever and severe abdominal pain, you should consider the alternative causes of the symptoms described below.

Alternative causes of symptoms

  1. Have I overexcited my gut in the past few days? Did I drink a lot of coffee, for example, or did I consume large amounts of sugar or sugar substitute, for example in the form of energy drinks, gummy bears or chocolate? Have I drunk a lot of alcohol and / or smoked a lot of cigarettes? Have I consumed a lot of animal fats - belly meat when grilling, roast goose or pork knuckle?
  2. Have I added too little fiber to my intestines, i.e. not eaten any fruits and vegetables, no legumes such as beans or chickpeas, or no flax seeds, pumpkin seeds etc.?
  3. Did the diarrhea start after a meal? Maybe there is an intolerance or food poisoning?
  4. Have I just come back from a trip? Could it be a travel diarrhea? This lasts for two to five days, coli bacteria or viruses are the cause.

At the latest when there is blood in the diarrhea, severe abdominal pain and fever, those affected should go to the doctor on the same day.

An immune response?

Crohn's disease affects all layers of the intestinal wall - but not all parts of the intestine are inflamed to the same extent. The exact cause is still unknown, but those affected show a lack of the body's own antibiotics; therefore, many researchers suspect a disturbed immune response on a genetic basis that may be activated by an infection. The antibiotics are missing, and therefore the intestinal mucosa cannot adequately ward off harmful bacteria. These bacteria then trigger the inflammation.

Crohn's disease primarily attacks the last part of the large intestine, but also affects every other section of the intestine, from the mouth to the anus. Inflammation occurs everywhere - when it heals, it leaves scars that can narrow the intestine.

If the disease is severe, nutrients from the intestine are processed insufficiently. Then weight loss and blood loss will result. The risk of developing colon cancer is increasing.

Colon cancer

Colon cancer usually arises from colon polyps, i.e. from benign growths. Preventive measures enable such polyps to be identified and removed so that they do not develop into a malignant tumor. These polyps can only be identified in preventive care because they do not cause any complaints.

Degenerate body cells

Colon cancer develops from normal body cells that degenerate. A healthy organism regulates the growth and multiplication of the cells - but the cancer cells cannot control this. They proliferate and grow in tissue where they do not belong and destroy healthy cells.

Cancer can have a genetic predisposition. In this case, the genetic material on which the body reads the information to produce proteins is changed. Or the control of genetic information is shifted: If it is read incorrectly, growth can result without control. A cancer cell is created by a series of such mutations. A change can be inherited genetically, but external factors also damage the genetic material - chemical substances or infections, but also an unhealthy lifestyle such as a diet that damages the intestinal tract.

The longer the organism is in operation, the more difficult it is to correct errors. Therefore, the older they are, the more often people get cancer.

Tumors in the mucous membrane

Colon cancer mainly occurs in the mucous membrane of the colon and rectum. However, tumors in the small intestine are rare. Carcinomas in the intestine are solid tumors. This means that the malicious mutations originate from an organ. These are usually the glandular cells of the mucous membrane that cover the intestinal walls. Other tumors in the intestine originate from the connective and lymphatic tissues; however, they are not considered colon cancer in the narrow sense.

Intestinal tumors usually develop in many years. Often only a single cell changes in the beginning and is destroyed by the immune system. Only when this control is suspended does such a cell share its genetic changes. Daughter cells develop, and these eventually form a tumor that is independently supplied with blood - the tumor.

Growths of the intestinal mucosa

Colon cancer usually arises from benign precursors. That is why colonoscopy is very important as a preventative measure: Here, growths of the mucous membrane can be identified, from which cancer develops.

Colon cancer is one of the most common forms of cancer. In 2016, an estimated 33,400 men and 27,600 women fell ill in Germany. Only lung cancer kills more people each year. Older people are affected much more often than young people; there is very little risk under the age of 40. However, the age limit does not apply to people who are burdened by their genetic material. If you suffer from familial adenomatous polyposis, you often get colon cancer at a very young age.

If you do not have an increased risk, you should have colon cancer screening from the age of 50, after which the risk increases. From this age, the statutory health insurance companies assume the costs for palpation of the rectum and for the test for hidden blood. From the age of 55, they also pay for a colonoscopy.

Every third colon cancer is genetically affected

Every third colon cancer is due to genetic risks. If you have such a family history, you should definitely take preventive measures at a young age. Preventive measures can also be taken in later years for people without an increased risk, since intestinal tumors very rarely develop early.

However, if you have a family disposition, you should take preventive measures at the age of 10, but at the latest at the age of 25 - in any case ten years before colon cancer first appeared in a family member.


Colonoscopy is called colonoscopy. Doctors examine the intestine with a special instrument - the colonoscope. What is a colonoscopy used for? How does such a colonoscopy go? Does it cause pain? When is it advisable, when is it essential? Are there alternatives? Those affected are faced with many questions.

What is colonoscopy used for?

Colonoscopy reveals diseases of the large intestine (colon) and at the end of the small intestine. Gastrointestinal specialists use colonoscopy in particular to identify colon cancer and to remove precursors of cancer - but also against other diseases of the intestinal tract.

When is a colonoscopy recommended?

Doctors think about a colonoscopy to clarify symptoms that indicate intestinal diseases. Especially with blood in the stool, those affected should urgently undergo a colonoscopy.

Colonoscopy is advisable:

  • from pension provision from the age of 55,
  • if there is a family disposition for colorectal cancer, before the age of 20,
  • if there is blood in the faeces with no known cause (such as hemorrhoids),
  • if you have blackish feces and no stomach problems,
  • with a primary tumor to detect metastases, especially if patients suddenly lose weight,
  • if you suspect chronic intestinal inflammation,
  • if you suspect non-chronic diseases of the intestine,
  • if the stool changes, as diarrhea or constipation - without other causes such as known foods and diseases,
  • for pain in the middle and lower abdomen without an alternative cause,
  • as a control after colon cancer treatment,
  • with iron deficiency,
  • with strong flatulence over a longer period of time.

When should you absolutely have a colonoscopy?

Affected people should have a colonoscopy done promptly, if

  • they have blood in their stools
  • the bowel function changes,
  • the chair deforms in "ribbon noodle", "coffee bean" or "pencil" form,
  • alternate intense diarrhea and constipation,
  • you can feel hardening in the abdomen from the outside.

When is regular colonoscopy important?

Colonoscopy is important, though

  • the patients already had colorectal cancer,
  • a relative has bowel cancer or other cancers,
  • has a chronic bowel disease.

Risk factors

Colonoscopy is still advisable in the current year if patients

  • To be overweight,
  • exercise very little,
  • eat a lot of meat and animal fat,
  • get too little fiber,
  • consume lots of alcohol and nicotine.

Doctors advise having a colonoscopy approximately every 8 to 10 years from the age of 50, even if the risk factors mentioned do not exist.

How do patients prepare?

Before an examination of the intestine and a colonoscopy, the intestine must be empty so that the examination is not hindered by food residues. Those affected therefore take a strong laxative the day before - as an intestinal lavage or as an enema.

The so-called PEG laxative solution discourages many sufferers. Until recently, those examined previously drank up to five liters of unpleasant-tasting liquid - in just a few hours. The bad taste can be improved by adding clear apple juice, meanwhile they are also available with lemon and orange flavor. If in doubt, the solution can be introduced using a gastric tube.

Osmotic and secretion-inducing laxatives offer an alternative, which patients consume with plenty of tea or water. However, this method sometimes shifts the water and mineral balance in the body. This puts a strain on the circulation and the intestine is not as clean as with the bad-tasting solution.

With a new powder preparation, patients only have to drink two liters of liquid to optimally clean the intestine instead of four liters as before. It's called Moviprep, it is dissolved in water and then drunk.

The survey

Before colonoscopy, the doctor interviews patients about

  • Family history: Have there been bowel diseases or cases of colon cancer in relatives?
  • physical changes: what is the appetite, do those affected lose weight without changing their diet or exercising more?
  • the bowel movements: are there any noticeable diarrhea or constipation, blood in the faeces, blackish faeces?
  • Flatulence that was not there before without consuming "suspicious" food (e.g. beans, cabbage, onions, beer)
  • Nausea and vomiting without alternative illnesses, physical overload (e.g. through rollercoaster rides, outdoor tours with a mountain bike) or harmful consumption of coffee in excess, alcohol in large quantities, medications with special side effects or narcotics.

Diagnosis and tests

Thereafter, the therapists listen to the abdomen in order to conclude from the bowel sounds how the bowel works and whether there are any symptoms. As a result, the abdomen is also scanned - possible resistance could be tumors. In addition, possible changes can be determined by tapping the abdomen. In a rectal examination, the practitioner takes smears to assess the mucous membrane.

A quick test for invisible blood in the faeces is carried out by a paper strip test. Such a test is advised annually for people over the age of 50. If such a test reveals blood in the stool, a colonoscopy is pending. However, colon cancer can also be present in the feces without blood.

Consent form

A tissue sample is legally a surgical procedure. Therefore, the patient must give his consent in the form of a signature. Information about the advantages and disadvantages of general anesthesia is also recorded in writing. Before taking a tissue sample, it is checked whether the patient has problems with blood clotting. For this, a few milliliters of blood are taken from an arm vein. The examination in the laboratory can take up to two days.

Affected people should inform the doctor whether they are taking medications that inhibit blood clotting - especially for heart diseases. This also applies to the spectrum of agents that contain acetylsalicylic acid (aspirin / ASA). At times, those affected have to withdraw them for a while. If necessary, those affected receive a sick leave from their doctor.

The colonoscope

Today's colonoscopes are approximately one centimeter in diameter and approximately 1.2 meters long. A video colonoscope contains a video chip at the tip that transfers images from the intestine to a monitor. Affected people can see what is going on inside them on the screen.

The colonoscope also has an aspirator that removes stool residues and irrigation fluid. A working channel offers space to insert instruments such as pliers and loops, which can be used to remove polyps and take tissue samples.

How does the colonoscopy go?

As with gastroscopy, patients can take sedatives such as midazolam if desired, as well as pain relievers such as pethidine and tramadol. Today, doctors also use Propofol and use it to perform general anesthesia. However, this is controversial, since half of the complications in the examination are due to this anesthesia - especially the cardiovascular and respiratory complaints.

When the doctor advances the device, it sometimes pulls on the hanging straps of the colon, which causes pain. The pain relievers completely suppress them. Patients under anesthesia are constantly monitored by a sensor on their finger that measures oxygen and pulse. The patients are initially on their back and when the anesthesia works, they are turned to the left side with their legs bent.

The practitioner pushes the colon tube down into the appendix or the last part of the small intestine. Then air is blown in until the intestine unfolds. Now the doctor examines the entire intestinal mucosa for pathological abnormalities. It takes about 25 minutes. The blown-in air often causes intestinal gas, but this almost always disappears.

Colonoscopy can detect the following symptoms: sagging, polyps, inflammation, intestinal diseases, ulcers, tumors, constrictions, mucosal bleeding, parasites and foreign bodies.

The treatment

Bagging is not a disease and does not require treatment. The bleeding should only be stopped if they bleed, which is possible with a colonoscopy. Inflamed bulges can injure the intestinal wall and should therefore not be removed as long as they are inflamed.

Although polyps are harmless, they can develop into colon cancer, which is why they are removed with a colonoscopy as a precaution. Ulcers are examined by forceps being pushed through the colonoscope to take samples of the mucous membrane. The doctor then examines these samples bacteriologically.

Tissue is taken from tumors. Preventive colonoscopy curbs cancer. A study in Saarland showed that 11.4% of patients who underwent colonoscopy for the first time had advanced cancer levels - against 6.4% of patients who had undergone colonoscopy in the previous ten years.

In narrow spaces, a balloon is inserted and blown up with the colonoscope. So the spot stretches. This method should only be used by specialists, because there is a risk of an intestinal tear.


Colonoscopy is a particularly safe routine examination today. As with all interventions in the body, complications sometimes occur. For example, blowing in the air or inserting the colonoscope can damage the intestinal wall. Then bacteria and intestinal contents may get into the abdominal cavity, which makes an operation necessary.

Removing the polyps and tissue can cause bleeding. However, these are usually stopped during treatment - by means of heme clips or injecting. Blood poisoning, on the other hand, is more serious if intestinal bacteria enter the blood. Then antibiotics are the order of the day. In the worst case, cardiac arrest threatens. The risk is generally higher in older patients than in younger ones.

In addition to physical complications that also arise when the procedure is carried out professionally, there are often difficulties caused by inexperienced doctors. Introducing a colonoscope is also an art, and those who act awkwardly easily damage the sensitive intestinal walls. This also applies if a "gross motorist" separates polyps and thereby injures the mucous membranes.

Colonoscopy as a precaution

Statutory health insurance pays a colonoscopy for prevention from the age of 55. Precaution means that a person undergoes a colonoscopy without showing any symptoms. A preventive medical check-up is always a consideration: Which complications can arise, is the risk worth the intervention?

Colon cancer screening

Regular colonoscopy is particularly recommended for colon cancer. Intestinal tumors can be treated well in the early stages. In addition, intestinal polyps are relatively common and these can mutate into cancer. After all, 114 out of 1000 patients show such protuberances at the first mirroring. This contrasts with complications in 35 out of 10,000 examinations. The possible negative consequences can therefore be classified as low in relation to the positive ones.

Colonoscopy also shows precursors of cancer very reliably - around 97 out of 100 potential tumors are recognized with it. However, the experience of the doctor plays a role, and therefore German doctors have to prove 200 examinations and 10 polyp ablation before they can settle outpatient colonoscopes with the health insurance company.

A comprehensive study in the USA showed that the death rate in colon cancer patients would decrease by 53% if the affected person had bowel polyps removed by colonoscopy beforehand.


Colonoscopy is often filled with shame, and hardly anyone is enthusiastic when another person inserts a tube through their anus into the intestine. Many do not admit this shame and fear, but rather, despite symptoms, do not go to an examination that could amount to a colonoscopy.

Doctors who perform such reflections are, however, experienced - even when dealing with those affected. They treat patients gently and safely. In case of doubt, it helps to be treated as a woman by a doctor and as a man by a doctor, or to speak openly to the person treating you about feelings of shame and fear and to seek advice from specialist staff.

After colonoscopy

Colonoscopy is generally not very stressful. 76 out of 100 respondents in a Berlin study described the study as "well acceptable", 16 as "somewhat unpleasant" and 7 out of 100 as "unpleasant but tolerable". Only 1 in 100 described it as "very unpleasant".

Those affected can eat again immediately after the mirroring, even if the doctor has removed polyps or removed tissue. When taking a narcotic, however, those affected should wait until the effect wears off. If the colonoscopy went without complications, those affected do not need to be physically gentle.


In the follow-up consultation, the doctor explains the result of the examination. Was the mucous membrane normal, were polyps discovered or did it even become a tumor? The patients send tissues and polyps to a laboratory. The microscopic results are available after several days.

If the colonoscopy showed no abnormalities, those affected should only repeat it after ten years. However, if there were polyps and / or precursors to cancer, those affected should undergo another colonoscopy in shorter periods.

If sufferers have not thoroughly cleaned their intestines, a doctor cannot fully assess the condition with a colonoscopy. Sometimes those affected have to repeat the examination.


Rarely, outpatient colonoscopy cannot be completed because intestinal polyps are so large that there is heavy bleeding after removal. A stationary colonoscopy is then added in order to observe those affected longer.

Sometimes intestinal constrictions, such as previous operations, prevent full colonoscopy. Perhaps the procedure can then be repeated with a thinner tube, which is used for children.

If those affected reject a colonoscopy, a virtual colonoscopy is sometimes an option. However, this does not remove polyps or foreign bodies, nor does it take tissue samples.

The small colonoscopy

A possible alternative is also a small colonoscopy, as a technical term sigmoidoscopy. The tube is pushed less far into the intestine, and only the rectum and the end of the colon are examined.

The advantage is that it takes less effort to examine and prepare, and there can be fewer complications. The disadvantage is that large parts of the large intestine remain hidden and the doctor does not recognize any tumors lying there. In the "Specialist Guideline for Colorectal Carcinoma", this examination is therefore only recommended for patients who refuse complete colonoscopy.

In virtual colonoscopy, images of the intestine are created using computer tomography. In contrast to colonoscopy, radiation exposure occurs here. Many doctors therefore reject this procedure for the diagnosis of colon cancer. The exceptions are: If a colonoscopy is too risky or is not possible due to narrowing.

Capsule endoscopy

Capsule endoscopy is a new method. Here, those affected swallow the camera as a pill. The pill has two cameras at each end and sends pictures from inside the body. It passes through the digestive tract and is excreted in the stool. So far, however, this method has not been sufficiently reliable since many tumors remain undetected. Complete colonoscopy is still the first choice for colorectal cancer screening. (Dr. Utz Anhalt)

Author and source information

This text corresponds to the requirements of the medical literature, medical guidelines and current studies and has been checked by medical doctors.

Dr. phil. Utz Anhalt, Barbara Schindewolf-Lensch


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