Endoscopic surgery of gastrointestinal tumors

Endoscopic polypectomy. The first endoscopic polypectomy was performed in 1969 by Suneko and Ashida - mechanical cutting with a loop. Later, they began to perform electroexcision. At first, polypectomy was performed only for single polyps on a stalk.

Polypectomy can be diagnostic or therapeutic. Diagnostic polypectomy is the establishment of a diagnosis after complete removal of the polyp by histological examination.

Indications for diagnostic polypectomy.

1. For all single polyps, if technically possible.
2. In case of polyposis - removal of 2-3 polyps with the largest dimensions and altered surface.

Indications for therapeutic polypectomy.

Indicated for all single or multiple polyps if the tumor size is greater than 5 mm (less than 5 mm - forming polyp) and if polypectomy can be performed without the risk of causing severe complications

Contraindications to polypectomy.

In addition to general contraindications to endoscopy, contraindications to polypectomy include disorders of the blood coagulation system.

Methods of polypectomy.

1. Excision (cutting off). Rarely used because there is a risk of bleeding. Used to remove small formations when it is necessary to know their histological structure.
2. Electroexcision is the main method of removing polyps. A loop is thrown onto the base of the polyp and tightened until the polyp changes color - the vessels compressed by the loop are thrombosed. After 2-3 minutes, while tightening the loop, the coagulator is turned on. From the standpoint of radicality, it is necessary that the loop captures the base of the neoplasm with the adjacent mucous membrane. With this arrangement of the loop, due to the spread of the coagulation necrosis zone towards the mucous membrane, the base of the polyp and the adjacent mucous membrane and even the submucous layer are completely destroyed. However, such a technique is unsafe, since there is a real threat of perforation of the organ wall. The intersection of the polyp stalk should be started with short pulses (2-3 s) at a low diathermic current strength to achieve a coagulating effect. The longer the coagulation and the wider the polyp stalk, the deeper and larger the area of the mucous membrane defect. The polyp should be removed slowly. As the vessels feeding the polyp coagulate, it changes its color - it becomes purple, bluish, and finally black. If the loop tightens quickly, the polyp is rejected before the vessels are completely coagulated and bleeding occurs.
3. Electrocoagulation. It is indicated, firstly, in the presence of small neoplasms with a base up to 5 mm wide and 2-3 mm high, which most often cannot be removed using a loop. Secondly, the electrocoagulation method can be used when loop electroexcision is incomplete. Thirdly, this method can be widely used to eliminate bleeding that occurs during loop electroexcision of neoplasms. The technique involves bringing an electric thermoprobe to the top of the neoplasm, after which the current is turned on. A necrosis zone occurs, which gradually spreads to the entire neoplasm, as well as to the surrounding mucous membrane at a distance of 1-2 mm from the base. Before electrocoagulation, it is necessary to perform a biopsy so that the morphological structure of the neoplasm is known.
4. Photocoagulation.
5. Medical polypectomy. 96-degree alcohol, 1-2% acetic acid, etc. are injected into the base of the polyp.

The technique of polypectomy is determined by the type of polyp. Yamada proposed a classification of polyps, which allows choosing the most appropriate technical method for removing a polyp of a particular type. According to this classification, there are four main types of polyps:

• Type I polyp is a plaque-like formation located on the gastric mucosa.
• Type II polyp - has the form of a hemisphere. Its consistency is soft. The stalk is absent, but when pressed with biopsy forceps, the formation shifts moderately.
• Type III polyp - round or oval in shape, located on a wide base (wide stalk). Such polyps sometimes reach large sizes.
• Type IV polyp - has a long stalk (sometimes several centimeters), easily moves in different directions.

For polyps of types III and IV, polypectomy using a loop is preferable. Such polyps are coagulated regardless of the thickness of the stalk and the size of the polyp. In cases where the stalk diameter does not exceed 4-5 mm, polyp excision with a loop can be performed without electrocoagulation.

Removing polyps of types I and II is not easy due to the complexity of throwing a loop and tightening it at the base. To carry out this stage of the operation, it is necessary to resort to various techniques: changing the size of the loop, the angle of its exit from the device, the method of throwing. When using two-channel endoscopes, it is much easier to accurately position the loop on the polyp. Biopsy forceps are inserted into the open loop, grasp the top of the polyp and lift it. Then the loop is lowered along the forceps, as along a guide, aimed at the polyp and tightened. If attempts to grasp a small stalk of the polyp in the loop are unsuccessful, it can be created artificially by injecting 5-20 ml of 0.25% novocaine solution under the base of the polyp with a loop through a two-channel.

It is important to note that when the loop is tightened and coagulated, the underlying and surrounding tissues are pulled to the cut area, creating an elevation (false stalk) with a defect in the center. This elevation may be incorrectly assessed as the result of incomplete removal of the neoplasm and serve as a reason for a repeat operation, which may be complicated by organ perforation.

Large polyps (more than 1.5 cm) can be removed in parts: by several captures with a loop electrode, the main part of the polyp is excised, and then its base. This method allows obtaining a scab, the area of which does not exceed the area of the polyp base. Removing the polyp in parts guarantees that the entire thickness of the organ wall, especially the thick one, is not captured. This method can be used for villous tumors and polyps with a short (less than 1 cm) and thick (more than 1 cm) stalk in which large vessels pass. Electroexcision in parts allows achieving good hemostasis.

For large polyps, a two-stage polypectomy is also used. A loop is tightened at the base of the polyp and the current is turned on, demarcation develops and a stalk is formed, and the polyp is cut off after 3-4 days.

Two-stage polypectomy is also used for multiple polyps. If the operation proceeds successfully and the patients are in good condition, one can aim for simultaneous cutting off and extraction of all polyps (up to 7-10). But if the patients do not tolerate the introduction of the endoscope well, then 3-5 polyps can be removed, and the operation can be repeated in 2-3 days.

Polyp extraction. Extraction of a single polyp is mandatory. In case of polyposis, extraction of each excised polyp is reliable, however, repeated insertions and withdrawals of the endoscope are unpleasant and not indifferent for patients. Polyps can be collected in a basket, but it is quite sufficient to extract the polyp with the greatest morphological changes. Extraction of excised polyps can be done in various ways: aspiration (suction of the polyp to the end of the endoscope), grasping them with biopsy forceps, diathermic loop and special instruments (trident, four-pronged, basket). The extraction method depends on the type of endoscope and the set of appropriate instruments. Glucagon can be used to suppress peristaltic movements of the stomach and esophagus walls, which prevent the removal of the drug.

After polypectomy, a control examination is carried out after 1 week, if there is no epithelialization - after another week. Epithelialization occurs after 1-3 weeks. For 3 years, the patient is observed once every 6 months. Then once a year throughout life.

Complications.

1. Bleeding - up to 5% of cases. The causes of bleeding are violations of the technique of electroexcision of neoplasms (rupture or mechanical cutting of the polyp, insufficient coagulation, prevalence of the cutting moment and rapid cutting), the formation of deep and extensive defects of the mucous membrane. To reduce the likelihood of bleeding after polypectomy, a solution of adrenaline in a dilution of 1:10000 is injected into the stalk of large polyps before their resection.
2. Perforation is a rare but serious complication that requires surgical treatment to eliminate. Perforations may be caused by prolonged coagulation, the use of high-power and high-strength current, a wide pedicle of the neoplasm, or a violation of the surgical technique (pressure on the organ wall, detachment of the neoplasm). The likelihood of perforation increases with increasing pressure on the wall and decreases with the introduction of 1-2 ml of 0.9% sodium chloride solution or other solutions under the base of the polyp.
3. Burns and necrosis of the mucous membrane outside the polyp zone - in 0.3-1.3% of cases. Occurs when the walls of the organ are touched by the apex of the polyp, the loop and the uninsulated metal part of the endoscope, or when there is liquid at the base of the polyp. In this case, the electric current can spread not only to the base of the polyp, but also to the walls of the organ. To prevent this complication, it is necessary to visually monitor the progress of the operation and ensure that there is no content in the lumen of the organ.
4. Long-term non-healing defects of the mucous membrane. In 95-99%, epithelialization of coagulation defects occurs within 4 weeks.
5. Relapses of the disease. The frequency of relapses of the disease and the appearance of new polyps in the stomach is 1.5-9.4%. If the polyp is not completely removed, its remains can be excised during a control endoscopic examination in the immediate postoperative period. Relapses at the site of removed polyps are associated with violations of the technique performed, and the appearance of new polyps in the distant period is a characteristic feature of polyposis as a disease.

Endoscopic removal of submucous neoplasms. Endoscopic removal of submucous tumors is performed for diagnostic and therapeutic purposes. Indications for surgery are determined by the possibility of its technical implementation and safety, as well as the prospect of extraction.

Without the risk of serious complications, the operation is technically feasible in the case of exophytic tumors, dangerous in the case of intramural tumors, and impossible in the case of endophytic tumor growth.

Contraindications to endoscopic treatment are:

1. large tumors (8-10 cm), which are dangerous to remove due to the possibility of complications and are difficult to cut into pieces for extraction;
2. endophytically growing tumors of any size;
3. malignant tumors with infiltration of surrounding tissues.

There are two types of endoscopic operations for the removal of submucosal tumors, which differ fundamentally from each other in technique and complexity of surgical procedures.

The first type is endoscopic electroexcision with a diathermic loop similar to conventional endoscopic polypectomy. This operation is performed for small (up to 2 cm) neoplasms that are assessed as polyps based on visual data. Only a histological examination can establish the non-epithelial nature of the removed tumor.

During endoscopic electroexcision, not only the tumor itself is captured in the loop, but also the surrounding tissues. When the loop is tightened, the tumor is squeezed out of its bed and moves up into the loop.

The second type of surgery is endoscopic excision (enucleation) of the tumor from the surrounding tissues with preliminary dissection of the mucous membrane covering it. It is performed in several stages:

• hydraulic separation of the tumor from surrounding tissues;
• dissection of the mucous membrane covering the tumor;
• excision of the tumor from surrounding tissues;
• tumor removal.

1. At the top of the tumor, up to 5-10 ml of 0.25% novocaine solution with 1 ml of 0.1% adrenaline solution are injected into the submucosal layer using a needle. This produces a hydraulic preparation of the tumor, which facilitates its excision and prevents bleeding from the bed.
2. The apex of the neoplasm is dissected with a diathermic electric knife. The length of the incision should correspond to the diameter of the tumor. As the dissection proceeds, the tumor prolapses into the incision due to the stretching of the organ walls by the introduced air.
3. Further actions depend on the depth of the tumor, the form of its growth, the nature of the relationship with the surrounding tissues. The main condition determining the success of the operation is the mobility of the tumor. To determine its mobility, it is necessary to take the tumor with forceps and vigorously move it. If there are no adhesions and the tumor is located superficially, then after the mucous membrane is cut, it protrudes significantly into the lumen of the stomach and it must be separated only at the base.

When using a single-channel fibroendoscope, this is easier to do with a diathermic loop, which is thrown over the base of the tumor and gradually tightened. If the tumor is freely enucleated, then the operation can be completed without using diathermic current. If an obstacle is felt during tightening, then electroexcision of the tumor is performed with periodic short (up to 1 s) current pulses. In this case, it is imperative to pull it up to the end of the endoscope.

When using a two-channel fibroendoscope, the apex of the tumor is grasped with holding forceps and pulled upward. The exposed strands between the tumor and its bed are dissected with a diathermic knife or scissors passed through the second channel. In the presence of adhesions and a deeply located tumor, it is possible to remove only with a two-channel endoscope and it is better to refuse the operation if it is not available.

If the tumor does not come out of the incision when pulled up and the adhesions are not exposed, then electroexcision is continued with a loop. The loop is gradually tightened by alternating "coagulating" and "cutting" currents, and the tumor is lifted and moved aside with holding forceps so that the depth of the incision can be visually controlled. It should be taken into account that adhesions are difficult to cut with electricity, and unlike conventional polypectomy, it is necessary to use a high-power current, but in short intervals, and widely apply mechanical extraction of tumors.

4. Tumors are removed using one of the known methods (special forceps, basket). The size of the tumor is important. Tumors larger than 3 cm in diameter are dangerous to remove, as they can damage the esophagus, so they need to be dissected and removed in parts. Postoperative management is the same as for endoscopic polypectomy.

Complications.

The risk of complications (perforations and bleeding) during endoscopic excision of submucosal tumors is significantly higher than during conventional polypectomy. In this regard, special attention should be paid to measures to prevent them: correct selection of patients for operations, determination of the depth of the tumor, availability of special instruments, and careful adherence to the surgical technique.

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