New Classifications of Intraoperative Bleeding and Muscularis Propria Injury in Endoscopic Resection
With the advancement of endoscopic techniques and equipment, endoscopic surgery has become a widely adopted method for treating various diseases, including early gastrointestinal cancer, submucosal tumors, and achalasia. Endoscopic surgery can be broadly categorized into two main techniques: the digestive endoscopic tunnel technique (DETT) and the non-tunnel technique. The non-tunnel technique encompasses several procedures such as endoscopic mucosal resection, endoscopic piecemeal mucosal resection, endoscopic submucosal dissection (ESD), multi-band mucosectomy, endoscopic submucosal excavation, and endoscopic full-thickness resection. On the other hand, DETT includes procedures like endoscopic submucosal tunnel dissection (ESTD), peroral endoscopic myotomy (POEM), and submucosal tunneling endoscopic resection (STER). Endoscopic resection is considered safer and less invasive compared to traditional open surgery and video-assisted surgery. The safety of endoscopic surgery is often evaluated based on the complication rate, with bleeding and perforation being the most common intraoperative complications.
A New Classification of Intraoperative Bleeding
The incidence of immediate bleeding during endoscopic procedures has been reported to range from 22.6% to 90.6%. However, accurately assessing the amount of bleeding during endoscopic resection remains challenging. There is no unified definition for intraoperative bleeding related to endoscopic resection, and only one study has proposed a classification method to define the degree of bleeding. This study graded immediate bleeding as follows: Grade 0 (no visible bleeding), Grade 1 (trivial bleeding that stops spontaneously or is easily controlled by a single session of hemocoagulation), Grade 2 (minor bleeding that is controlled by multiple sessions of hemocoagulation or is easily controlled by hemoclips), and Grade 3 (major bleeding that requires multiple hemoclips and sessions of hemocoagulation). This classification, however, is not entirely accurate due to its limitations. The standards for evaluating immediate bleeding rates vary across studies, making the results incomparable. Immediate bleeding is believed to be influenced by both the characteristics of the lesions and the experience of the operators. Evaluating the amount of bleeding during endoscopic operations is more difficult than during surgical operations, and the operators’ experience significantly affects the hemostatic time. Therefore, grading intraoperative bleeding based solely on the amount of bleeding and hemostatic time may not be appropriate.
A new classification of intraoperative bleeding, termed the endoscopic resection bleeding (ERB) classification, has been proposed based on 30 years of endoscopic experience. The ERB classification is suitable for evaluating the amount of bleeding during both DETT and non-tunnel resection. It is divided into three main grades, with five sub-grades as follows: ERB-0 indicates no bleeding, as the exposed vessel was immediately treated by electrocoagulation. ERB-controlled (ERB-c) refers to bleeding that can be controlled by endoscopy. ERB-c is further divided into three sub-grades: ERB-c1 (minor bleeding that can be easily controlled by endoscopy without affecting postoperative vital signs and without the need for blood transfusion), ERB-c2 (bleeding with an amount between c1 and c3), and ERB-c3 (major bleeding that can be controlled under endoscopy but requires blood transfusion intra- or post-operatively). ERB-uncontrolled (ERB-unc) refers to uncontrollable bleeding under endoscopy that must be treated by surgery or vessel embolotherapy.
A New Classification of Muscularis Propria Injury (MPI)
The incidence of perforation related to endoscopic procedures has been reported to range from 1.2% to 4.1%. Perforation typically refers to a full-thickness injury of the muscularis propria (MP). Mucosal injury is an inevitable part of non-tunnel resection, and perforation often indicates injury to the MP layer. However, the term “perforation” can cause significant psychological stress to patients and does not accurately evaluate the severity of MP injury (MPI). To address this, a new MPI classification has been proposed to better quantify the severity of lesion adhesion, the proficiency of the operation, and the condition of the postoperative wound. The MPI classification is divided into three main grades, with five sub-grades as follows: MPI-0 indicates no injury to the MP. MPI-injury (MPI-i) refers to partial injury of the MP without full perforation. MPI-i is further divided into two sub-grades: MPI-ia (partial injury of the MP where the gas inside the cavity does not penetrate out of the cavity after pressurization) and MPI-ib (partial injury of the MP where the gas inside the cavity penetrates out of the cavity after pressurization). MPI-perforation (MPI-p) refers to full-thickness injury. MPI-p is further divided into two sub-grades: MPI-pa (perforation that can be closed under endoscopy) and MPI-pb (perforation that cannot be closed under endoscopy and must be treated by surgery). The MPI classification is suitable for evaluating MP injury during non-tunnel resection.
A New Classification of Muscularis Propria Defect (MPD) During DETT
Compared to non-tunnel resection, DETT has the advantage of maintaining the integrity of the mucosa. However, incision and resection of the MP layer during DETT can result in defects of the MP layer. The classification of MP defect (MPD) during DETT is different from that of non-tunnel resection. The MPD classification is suggested to classify the defect grade of the MP layer and includes three main grades: MPD-0 (no defect of the MP), MPD-p (partial defect of the MP without full perforation), and MPD-f (full defect of the MP with perforation). When MPD-f is diagnosed, the location and the circumferential degree of the lesion should be mentioned. The MPD classification is indicated to evaluate the defect grade of the MP layer during ESTD, POEM, and STER.
These three classifications—ERB, MPI, and MPD—are based on 30 years of clinical experience. The ERB classification offers a relatively accurate evaluation of the severity of intraoperative bleeding, although it is influenced by the experience of the operators and the equipment used for hemostasis, in addition to the lesion itself. Similarly, the MPI and MPD classifications are also related to the experience of the operators and the equipment used. The MPD classification can also serve as a predictor for diverticulum and postoperative scarring that may cause stricture. Therefore, these classifications can be used to estimate the level of different centers and the ability of different doctors. Immediate hemostasis is essential to provide a satisfactory endoscopic view, which can decrease the incidence of MPI and defects. Lesions in the upper stomach, lesions larger than 20 mm, and excessive coagulation and hemostasis have been identified as risk factors for perforation during ESD. Good fluid cushion and repeated injection during resection are essential to ensure the integrity of the MP.
These classifications aim to standardize the reporting of complications during endoscopic procedures. They are intended to increase the knowledge of both physicians and patients regarding complications related to endoscopic resection. By providing a more accurate and detailed classification system, these classifications can help improve the safety and efficacy of endoscopic surgery, ultimately leading to better patient outcomes.
doi.org/10.1097/CM9.0000000000000357
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