Procedure
As a rule, the patient can decide whether he/she wants to receive a sedative (e.g. midazolam) or a short anaesthetic (usually with Propofol) so that he/she does not notice anything from the examination. It should be noted, however, that in this case the ability to drive for 24 hours is considered to be limited. First, the patient is given a so-called flexula, a small tube that lies in the vein so that the sedative or narcotic can be injected.
Before this is done, the patient is usually positioned on his side. In addition, a pulse oximeter is connected to one of the patient’s fingers to measure oxygen saturation and pulse. The sedative/narcotic is injected, then the patient waits until it takes effect.
The examiner then begins to carefully insert the colonoscope rectally and advance it until it reaches the foremost part of the colon or the last part of the small intestine. The colonoscope is then slowly retracted and air is insufflated (blown in) into the intestine so that it expands, which significantly improves visibility. This air can sometimes cause slight flatulence after the examination.
Then all sections of the colon are carefully examined. During colonoscopy, not only can the intestine be assessed, but small procedures can also be performed if necessary. This is made possible by small tools that can be inserted into the colonoscope.
For example, in the case of minor bleeding in the colon, haemostasis is possible by means of injections. If colon polyps (protrusions of the mucous membrane that over the years threaten to degenerate into a colorectal carcinoma) are discovered, they are usually removed in the same examination. In the case of narrowing (stenosis) of sections of the intestine, these sections can be widened again during the examination (bougienage).
If conspicuous areas of the mucous membrane are discovered, a small tissue sample (biopsy) can be taken from these and then sent to a laboratory for examination. The entire examination usually takes about 15-30 minutes. Afterwards, the patient may eat and drink normally again.
If the patient has been given a sedative or anaesthetic, he or she will remain in the facility for some time for monitoring and can then be discharged home. In this case, however, driving is no longer permitted on this day. As a rule, the patient has no complaints after the examination.
Occasionally there is a slight flatulence and a slight feeling of dizziness which can last for the rest of the day and is due to the sedative / narcotic. If symptoms such as fever, malaise or severe abdominal pain occur after the examination, a doctor should be consulted. A frequent finding are polyps of the intestine.
These do not initially cause any symptoms, are therefore not noticed by the patient and are usually only noticed during a preventive examination. Polyps of any kind must be removed, as they can develop into dangerous carcinomas. In most cases, these polyps are immediately removed with the help of an electrical loop and sent to the pathologist for diagnosis.
Larger polyps must be removed with a small knife. In some cases a small suture is necessary after removal. Bleeding is also often seen during a colonoscopy.
Depending on whether the bleeding is acute and injects or older and already stopped, the injured vessel must be ligated with the help of a small electrical device. Sometimes it is necessary to inject adrenaline into the vessel to close it. If the vessel is bleeding heavily, the vessel must be closed with a suture.
Small inflammations of the intestinal wall are usually only documented by photographs in addition to the taking of a sample. All these colonoscopy procedures are possible with a colonoscope under certain technical transformation. Depending on the findings, the duration of a colonoscopy can vary greatly.
In addition, the anatomical conditions also play a major role. The more tortuous a colon is, the more difficult it is for the examiner to manoeuvre the colonoscope through the coils. The visibility also plays a major role.
If the patient has performed the colonoscopy too shortly before the examination and the intestine is not clean, the examination time may be extended. Depending on the findings and the number of samples taken, a shorter or longer examination time can also be achieved. The duration of a colonoscopy is between 20 minutes and one hour, taking the above factors into account.
Every procedure carries risks, even though colonoscopy is generally considered to be very low-risk and safe. In Germany, numerous therapeutic or diagnostic colonoscopies are performed every year and complications are rare. However, risks are also pointed out before every colonoscopy.
These include first of all intolerance to the anaesthetic. It is true that the doses are usually small and therefore the anaesthesia times are short. However, intolerance reactions can always occur and require intensive medical follow-up treatment.
During the colonoscopy and after the examination, bleeding may occur which may also require further medical action. Bleeding can occur especially when skin areas are biopsied or when polyps are removed. Even after the procedure, a drop in haemoglobin in the blood count should make one think of bleeding caused by the colonoscopy.
While the colonoscope (special tube) is moved back and forth through the intestine and manoeuvred over curves and past angles, in individual cases there may be perforations in the intestine, which in the worst case can end in the rupture of the intestine and result in an emergency operation during which the intestine must be sutured and the abdominal cavity cleaned of bacteria from the intestine to prevent serious blood poisoning. However, this complication is extremely rare and in most cases can be prevented. It can also affect the organs located in the immediate vicinity of the intestine.
If a perforation occurs, open surgical abdominal surgery may be necessary. After bleeding or perforation, wound healing disorders and inflammation may occur, which also require special medical treatment. Less dramatic are superficial injuries to the intestinal wall caused by the tube, which can lead to bleeding, as well as post-operative bleeding after taking samples or removing polyps from the intestine.
These bleedings have to be stopped already during the examination or make a follow-up examination necessary if the bleeding occurs later after the examination. As with all medicines, allergic reactions to all the materials and medicines used can occur, which can end in life-threatening allergic shock or even death. Any intake of medication and allergies should therefore be discussed in the preliminary consultation in order to keep the risk as small as possible.
All these complications are very rare and many can be prevented by sufficient experience of the examining physician, but nevertheless one must always point this out in the run-up to the examination, as there is no guarantee to be spared from them. However, the risk generally increases with the age of the patient. The risk also increases for patients with a chronically inflamed intestinal wall such as Crohn’s disease. Since the intestinal wall is more vulnerable in this case, the examination is never carried out during an episode of illness under normal circumstances and otherwise only with great care.
