Anatomically, the human intestine is divided into 4 sections:
The following diseases can occur in the bowel:
Below you will find further information on these diseases.
The vast majority of benign tumors in the intestine are so-called polyps (adenomas) of the colon. These benign tumors can be detected during a colonoscopy and can also be removed directly without surgery during the colonoscopy.
As benign tumors always degenerate over time, they must always be removed. It is estimated that it takes about 10 years from the development of a benign tumor to its transformation into a malignant tumor (development of colon cancer). For this reason, colonoscopy is recommended every 10 years as a preventive measure to prevent colorectal cancer.
Figure 1: Adenoma in the colon
Malignant tumors are also found almost exclusively in the colon for the reasons mentioned above. These are tumors that initially develop from benign tumors of cells of the colon mucosa and then degenerate into colon cancer. Colorectal cancer starts to grow from the inside of the bowel and can constrict the bowel, which can lead to intestinal obstruction.
Over time, however, the tumor grows further into the wall of the intestine and can also grow outside the intestine into other organs. A general characteristic of malignant tumors is their ability to spread tumor cells and form metastases.
In the case of bowel cancer, such tumor cells can spread to lymph nodes in the bowel, so that these then form metastases and show malignant growth themselves.
Figure 2: Malignant tumor in the colon
As the lymphatic vessels and lymph nodes are located along the blood vessel supply in the bowel, it is essential that the associated lymphatic drainage area of the affected section of the bowel is also removed during bowel surgery, as otherwise further tumors may develop from any lymph nodes that remain.
Another mechanism by which bowel cancer can spread is the dissemination of cancer cells via the bloodstream. The cancer cells then preferentially settle in the liver or lungs and form metastases there.
Figure 3: Malignant tumor in the colon
Diverticula are outward protrusions of the intestinal wall. They are therefore always benign changes. These diverticula occasionally occur in the small intestine, but much more frequently in the large intestine.
Diverticula can be congenital, but in most cases they develop in middle age. The protrusions are usually caused by increased pressure in the large intestine; a congenital weakness of the connective tissue also appears to play a decisive role.
Diverticula occur at an advanced age in around 70 percent of people in industrialized countries and do not in themselves constitute a disease.
Figure 4: Diverticula in the small intestine
However, diverticula can cause painful inflammation of the intestine(diverticulitis) through mechanisms that are not yet fully understood, which can progress to intestinal perforation and life-threatening peritonitis.
Diverticula often occur in the entire large intestine, but most frequently in the so-called S-shaped section of the intestine in front of the rectum (sigmoid colon). The inflammations often occur in episodes and can lead to narrowing of the bowel after years. In addition to inflammation, severe bleeding into the bowel can also occur due to the diverticula.
Figure 5: Diverticular openings in the colon
Figure 6: Diverticula in the large intestine
This disease, the cause of which has not yet been clarified, leads to severe inflammatory episodes, sometimes lasting many years or decades. They mainly occur in the lower section of the small intestine, but sometimes also in the large intestine or rectum.
The disease occurs most frequently in younger people, with women being affected more often.
This inflammation of the bowel is primarily treated with medication. However, if severe complications such as intestinal perforations, constrictions or fistulas occur, bowel surgery is usually required. The affected section of bowel is removed as sparingly as possible.
Figure 7: Chronic inflammatory bowel disease (Crohn's disease)
Adhesions in the abdominal cavity occur after inflammation or surgery. In most cases, these adhesions do not cause any problems, but occasionally they can lead to symptoms if sections of the intestine have grown together or if there are adhesions to the abdominal wall.
These more extensive adhesions can mean that the bowel can no longer move freely or can only pass through narrow areas and kinks with difficulty.
Intestinal surgery is necessary if the symptoms can be clearly attributed to these adhesions.
Figure 8: Intestinal obstruction (ileus) in the small intestine
In addition, adhesions in the form of strands (brides) can form, particularly as a result of an operation, around which the bowel then loops, which can then lead to an acute intestinal obstruction (ileus).
This condition can mean that the blood supply to the intestine is no longer guaranteed and damage to the intestine occurs which, if left untreated, can lead to the death of the intestinal section. In this situation, only timely bowel surgery can prevent the damage and loss of the bowel.
Intestinal surgery is performed by specialists in visceral surgery or specifically intestinal surgery. The field of proctology is generally specialized in intestinal diseases. Coloproctology competence centers bring together experts from various disciplines who deal specifically with diseases and treatments of the rectum.
There are basically two surgical techniques to choose from for a bowel resection:
Figure 9: Laparoscopic surgery (laparoscopy)
The type of surgical procedure used for partial bowel resection essentially depends on the underlying disease. For example, in the case of a malignant disease, a larger part of the corresponding section of bowel usually has to be removed than would be necessary in the same section of bowel for a benign disease.
Open procedures require a larger abdominal incision, while laparoscopic procedures (minimally invasive technique, "keyhole surgery") do not require a large incision and are performed without direct access inside the body.
The two procedures do not differ in the extent of bowel removal, but only in the access route to the abdominal cavity.
Open abdominal surgery is still the most frequently performed surgical procedure in Germany for partial bowel resection.
Under general anesthesia, the abdominal cavity is opened via an abdominal incision, usually in the midline of the abdomen above and/or below the navel. During a partial bowel resection, the bowel is then released from its natural adhesions and prepared for removal of the section in question.
The blood vessels supplying the section of bowel in question are cut off and the bowel section is then severed. The two sections of bowel are then connected either by sutures or by appropriate mechanical staplers. The abdominal wall is then closed with sutures.
Figure 10: Open surgery
In principle, the actual extent of the removal of the bowel in laparoscopic surgery does not differ from open surgery. The main difference is that the access route to the abdominal cavity is as small as possible.
This is made possible by special sheaths (trocars), which are inserted into the abdominal wall through small incisions of between 5 and 10 millimeters. These trocars are then used to operate with special instruments in the abdominal cavity under visualization via an endoscopic camera, the image of which is transmitted to a monitor in the operating theatre.
The free space in the body required for the operation is made possible by the flow of harmless carbon dioxide gas into the abdominal cavity.
All surgical steps can be carried out safely in the abdominal cavity using special instruments and stapling devices, similar to open surgery. An incision of a few centimetres in the abdominal wall may only need to be made to remove the intestinal tissue from the abdominal cavity.
The main advantages of the minimally invasive technique are that patients experience very little pain after the operation due to the small incisions in the abdominal wall and recover much more quickly from the procedure. Other advantages include a shorter hospital stay and only very small scars.
Figure 11: Laparoscopic surgery
Figure 12: Wounds after laparoscopic surgery
A partial bowel resection can be performed using various surgical procedures:
In this procedure, only part of the intestinal wall is removed, for example to surgically remove a benign polyp that is widely attached to the intestinal wall and cannot be removed endoscopically.
The continuity of the bowel remains intact. The ablation site can be closed either with sutures or with a stapling suture instrument.
In the case of benign diseases of the small or large intestine, the operation is limited to the sparing removal of the affected section of the intestine, which is the surgical principle particularly in the case of chronic inflammatory bowel diseases.
The sections of bowel in front of or behind the removed section are reconnected using sutures or a stapling instrument.
This refers to the removal of the right-sided part of the colon(ascending colon) up to the transversecolon (transverse colon). This procedure is performed on tumors of the right-sided colon with removal of the supplying blood vessels and lymph vessels.
After removal, the end of the small intestine (ileum) is reconnected to the transverse colon (transversum).
In the case of tumors that are located exactly in the middle of the transverse colon, the entire transverse colon is removed while also removing the right and left bends of the colon(flexure) and then the right-sided colon(ascending colon) is connected to the left-sided colon(descending colon).
This refers to the removal of the left-sided part of the colon(descending colon) starting at the transverse colon(transverse colon). This procedure is performed on tumors of the left-sided colon with removal of the supplying blood vessels and lymph vessels.
After removal, the end of the transverse colon is reconnected to the rest of the colon.
Tumors in this S-shaped section of the intestine can be treated by removing this part of the intestine alone while also removing the blood vessels and lymph vessels supplying it.
However, diverticular disease occurs much more frequently in this section of the colon, which makes it necessary to remove this section of the bowel if it occurs frequently or if an inflammatory episode is severe. These procedures are preferably performed in most clinics today using laparoscopic surgical techniques, i.e. minimally invasive.
In the case of tumors of the rectum, which corresponds to the lower 16 centimetres of the bowel, part or all of the rectum must be removed. During the operation, the surrounding fatty mantle around the rectum, in which the lymph nodes are located, must also be removed.
The greater difficulty of this bowel operation is due to the fact that the rectum lies very deep in the small pelvis and is therefore more difficult to access for surgery. After removal of the rectum, the remaining rectal stump is reconnected with the sphincter muscle to the colon above.
Nowadays, this operation can also be performed using a minimally invasive technique that is gentle on the patient if the surgeon has the necessary experience.
In principle, with generally improved surgical techniques, it is now possible to preserve the sphincter muscle even in the case of tumors that are close to it. However, it must be mentioned that the rate of suture leakage in these operations is higher than in operations in other areas of the colon, so that an artificial stent is usually inserted for a shorter period of time as a safety measure, which can later be repositioned without consequences.
If the tumor is located on the sphincter muscle, it is necessary to remove the rectum while also removing the sphincter muscle.
The operation is otherwise performed in the same way as rectal surgery with sphincter preservation and is nowadays preferably performed using a minimally invasive technique if the patient has the relevant experience.
Once the sphincter muscle has been removed, an artificial bowel outlet(stoma) is created, which can nowadays be easily fitted with the appropriate supply systems so that patients are hardly restricted in their activities.
Removal of the entire large intestine(colon) may be necessary in the case of a chronic inflammatory bowel disease such as ulcerative colitis if the entire large intestine is affected.
In this case, the colon is completely removed and a reservoir (pouch) is formed from the lower part of the small intestine, which is then connected directly to the lower rectum above the sphincter (ileo-anal pouch).
This operation is performed almost exclusively using a minimally invasive technique in predominantly younger patients.
Benign tumors in the rectum are located in an area between the sphincter muscle and the transition between therectum and the lower colon(sigmoid colon). They present the difficulty that they are difficult to reach from the abdominal cavity, meaning that local removal is not possible.
However, local removal of benign adenomas from the rectal wall is possible during surgery via the anus, in which a minimally invasive removal of a tumor is possible with the help of a special rigid endoscope.
This procedure is particularly useful at a distance of between 8 and 12 centimetres from the sphincter muscle, as this area cannot otherwise be reached from the anus. Benign tumors located closer to the sphincter can be easily removed from the rectal wall under direct vision.
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