Colonic transendoscopic enteral tubing (TET) is an interventional intestine therapeutic procedure. The colonic TET technique represents a novel drug delivery route, interventional diagnosis and therapy, and paradigm for concept validation, showing broad prospects in research and practice. Since its first meeting at the China Gut Conference in 2023, our panel of experts has held a series of discussions on TET’s concept, breakthroughs, and future. We strive to lay the groundwork for further establishing the TET Study Group for designing multicenter studies and developing relevant consensus or guidelines.

The concept and application of colonic TET: The colonic TET concept was first reported in 2015.[1] Colonic TET requires inserting the colonoscope twice. The first insertion places the TET tube at the target location through the endoscopic channel. The second insertion affixes the TET tube to the intestinal wall using endoscopic clips. By 2023, colonic TET has been used in over 10,000 adults and children. Colonic TET has three major applications in clinical practice and research: frequent and timely delivery of microbiota and medications, drainage and decompression for colonic perforation and ileocolic obstruction, and sampling for microbial research [Figure 1].

Figure 1:

The diagram of colonic TET for delivering, drainage, and sampling. TET: Transendoscopic enteral tubing.

Delivering fecal microbiota through colonic TET essentially meets the physiological needs of the direct transplantation of microbiota from a healthy donor’s colon to the patient’s colon, the core process in fecal microbiota transplantation (FMT).[2] Drugs such as mesalazine, corticosteroids, hemostatic, traditional Chinese medicine, electrolytes, and contrast agents can be delivered through a colonic TET. Moreover, colonic TET can be used for conceptual validation of approved or potential drugs that can exert their potential effects through the colonic route, such as probiotics, and bacteriophages. The experts of the TET Study Group consider the retrograde administration of contrast agent via colonic TET and imaging stenosis, ulcer, mass, and fistula with fluoroscopy or computed tomography (CT) to compensate for the deficiency in the diagnostic efficiency of a CT scan with or without contrast, improving the clinical diagnosis.

Colonic TET can be used to provide samples from the deep colon for exploring host-microbiota interactions. In 2021, Liu et al[3] demonstrated for the first time the diurnal patterns or circadian rhythms in composition and function of the human gut microbiome based on sampling the ileocecal microbiota in situ through a colonic TET. Using colonic TET, researchers can accurately locate the terminal ileum and deep colon for real-time sampling of intestinal specimens for exploring dynamic microbial changes or pharmacomicrobiomics in situ.

The goal of colonic TET in rescuing endoscopy-associated perforation is zero transfer to surgery or zero ostomy surgery: Iatrogenic colonoscopy perforations can be caused by screening endoscopy and therapeutic procedures. A greater risk of iatrogenic colonoscopy perforation is associated with advanced age, female sex, low-volume practices, history of diverticular disease and inflammatory bowel disease (IBD), previous abdominal surgery, colonic obstruction, and deficient endoscopist experience.[4,5] Endoscopic clips[6] are effective for the closure of defects. However, patients with signs of abdominal infection generally are required to be transferred to surgery for irrigation, drainage, and repair, while colostomy should be performed simultaneously for patients with severe infection.

In 2021, Zhang et al[7] reported that timely drainage using a colonic TET could be an effective method to avoid surgery in patients with endoscopy-associated perforation for the first time. The colonic TET is used to rapidly drain the air and fluid from the intestinal tract with syringe suction to divert the digestive luminal contents and decompress intestinal tension. The enlarged intestinal cavity can collapse rapidly, reducing the digestive luminal contents and microbiota flow from the perforation into the abdominal cavity, which can prevent severe infection and peritonitis. The drainage and decompression via a colonic TET have been used to avoid surgery or bridge emergent surgery and scheduled surgery.[7,8] Essentially, it still embodies “effective decompression and drainage” as the core of surgery over the centuries.

The diagnostic and therapeutic endoscopy has developed rapidly worldwide over the past two decades. Notably, in developing areas, the incidence of complications that occur during endoscopic procedures still needs to be paid closer attention.[9] Endoscopists may consider the necessity for surgery when facing endoscopy-associated perforations; the uncertainty of the outcome is just like Schrödinger’s cat, which is both alive and dead. Therefore, doctors need new technology to support decision-making. Efforts should be taken to successfully rescue complications such as perforations to develop gastrointestinal endoscopy into a super minimally invasive surgery.[10] According to the unpublished early cohort studies, rescuing endoscopy-associated perforations via colonic TET improves the clinical setting.

What is the goal of using colonic TET to rescue endoscopy-associated colon perforations? One expression is “zero transfer to surgery,” and the other is “zero ostomy surgery.” Their difference lies in their varying degrees of reducing perforation-related organ injury.

To achieve the goal of zero transfer to surgery, the TET Study Group recommends the following items based on their experience: (1) Preliminary management should be performed when the doctor anticipates or detects a perforation. During endoscopy, colonic TET should be used immediately for drainage, decompression, and carbon dioxide insufflation. (2) Proper, timely, and near-perforation placement of the TET tube is required during endoscopy. Multiple aspirations, decompression, and drainage should be performed. For left-sided colon perforation, regular rectal decompression and drainage can be used along with antibiotic treatment. (3) There are two options for colonic TET tubes: 2.7 mm and 3.3 mm (FMT Medical, Nanjing, China), with the latter more advantageous for efficient decompression and drainage. (4) Basic techniques such as tissue clipping and purse-string suturing are crucial for managing endoscopy-induced, passive, and large perforation. When there is abundant intra-abdominal gas, intraoperative needle aspiration of the abdominal cavity and observation of gas release using a normal saline water-sealed syringe can be performed. (5) Closure operations may be challenging for delayed perforations. However, if the perforation is small, early and timely managed, colon TET drainage can still be successful. (6) The goal of achieving zero transfer to surgery depends mainly on endoscopists’ timely use of colonic TET drainage and decompression. Successful drainage and decompression show comprehensive signs in patients within 6–12 h.

To achieve the goal of zero ostomy surgery, the experts recommend the following items based on their experience: (1) When colon perforation requires surgical intervention, the ideal surgical approach is primary perforation repair and intra-abdominal drainage via a tube. However, when a surgeon chooses to perform an ostomy, a subsequent re-anastomosis procedure will be needed, which is a consequence that both the doctor and the patient should consider seriously. (2) During surgery (mainly laparoscopic repair), combining colon TET for decompression and drainage with endoscopy is recommended. Carbon dioxide insufflation should be used during endoscopy. Rectal decompression can also be performed for perforations near the rectosigmoid region. These decompression techniques can enhance the surgeon’s confidence in avoiding ostomy surgery. (3) Proper, timely, and repeated aspirations for decompression and drainage are essential to prevent postoperative anastomotic leakage.

In conclusion, the clinical outcome of the patient should be determined by decisions rather than luck, the timely implementation of TET decompression and drainage rather than hesitation, and actual decompression and drainage rather than only the formal presence.

Why should physicians, researchers, and patients care about TET? Allegretti et al[11] in the Lancet commented that the colonic TET is a promising direction in the future. A randomized controlled trial has shown that cap-assisted colonoscopy can reduce the second insertion time during the colonic TET tube implantation process to 2.2 min compared to conventional colonoscopy, especially for patients with constipation.[12] The success rate of colonic TET procedure is 100% (303/303). No serious adverse events have been observed during the endoscopic procedure, the retention period, or the tube removal period.[1] In patients with anal lesions such as anal ulcers or fissures, adjusting the orientation of the TET tube fixation can minimize stimulation at the affected part. According to the left, posterior, right, and anterior (LPRA) endoscopic anal rapid positioning method (LPRA anus positioning method), the direction of fluid accumulation is toward the left side of the anus with the left lateral decubitus position. In a clockwise direction, the positions including the anus (even the intestine) are sequentially left, posterior, right, and anterior.[13] If the anal lesion is located on the left side of the anus, the TET tube is fixed toward the right buttock. The satisfaction rate with colonic TET is 98.1% (53/54)[1] and most preferred it as the first choice. The mean length of the TET tube inserted into the colon in adults was 85.9 cm.[12]

In summary, colonic TET is a new concept and technology for research, diagnosis, and treatment centered around the intestine, promoting the development of microbiota medicine.

TET Study Group

Gaochen Lu, Nanjing; Lihao Wu, Guangzhou; Xin Wang, Xi’an; Huihong Zhai, Beijing; Quan Wen, Nanjing; Bota Cui, Nanjing; Xiaomeng Jiang, Nanjing; Jia Hu, Nanchang; Yan Jin, Wuxi; Liqing Yao, Shanghai; Lin Miao, Nanjing; Guifang Xu, Nanjing; Rui Li, Suzhou; Wei Wei, Beijing; Yongzhan Nie, Xi’an; and Faming Zhang, Nanjing. The entire information of the study group is shown in the Supplementary File 1, https://links.lww.com/CM9/B903.

Funding

This work is supported by the National Key Research and Development Program (No. 2021YFA0717004).

Conflicts of interest

Faming Zhang conceived the concept of GenFMTer and transendoscopic enteral tubing and related devices. The others declare no conflict of interest.

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