1.1 General Information
A total of 38 patients who underwent colonoscopy and EUS diagnosis of carcinoids at the endoscopy center of our hospital from January 2019 to May 2020 were selected for study inclusion. Their lesions ranged in diameter from 0.6 to 2.0 cm. All patients were examined by colonoscopy and computed tomography (CT) before their operation. To be eligible for study inclusion, their tumor borders needed to be clear, without surrounding organs and tissues or distant metastasis. Patients who relapsed after previous surgical treatment and/or who could not tolerate anesthesia were excluded.
Prior to surgery, doctors talked with patients and their families in detail about the advantages and disadvantages of precut EMR as well as the possible risks of surgery. Study participants were those willing to undergo endoscopic treatment and follow-up and who signed the treatment consent form. This study complied with the appropriate ethical regulations.
1.2 Materials
In this study, the following equipment was used: a CF-H260 electronic colonoscope, hot biopsy forceps, and KD-612L IT nano-knife from Olympus (Tokyo, Japan); an AF-D2423PN disposable sterile endoscope injection tube from Shanghai Elton Medical Instrument Company (Shanghai, China); an SD-T-1823-25 disposable electric trap from Jiangsu Kangjin Medical Instrument Company (Jiangsu, China); an HA-L-4 disposable hemostatic clip from Jiangsu Anrei Medical Instrument Company; and a VI0200D+APC2 endoscopic electrosurgery workstation from Erbo Medical Equipment Company (Tuebingen,Germany). Also, the Angus UW-600 endoscopic water pump and Olympus CO2 pumping system were used (Tokyo, Japan). A submucosal injection of glycerin, fructose, sodium chloride, and methylene blue solution was adopted, and a transparent cap was installed on the colon lens.
1.3 Treatment method
1.3.1 Preoperative preparation
Patients underwent complete preoperative examinations, except for those with contraindications to surgery and anesthesia. Oral anticoagulant and antiplatelet drugs needed to be discontinued for more than seven days. All patients were given polyethylene glycol 4000 powder (PEG-4000). Patients were instructed to prepare their bowels and adopt dietary restrictions, including a low-residue and low-fiber diet for 24 hours before treatment. Patients took 1 L of PEG-4000 orally at 9:00 pm on the day before the examination and another 2 L of PEG-4000 four to six hours before the examination until clean water was eliminated.
1.3.2 Ultrasonic testing
During testing, the operator cleaned the intestinal tract, located the lesions, injected normal saline into the intestinal tract, and immersed all the lesions in water. We inserted the small-probe endoscopic ultrasound device into the endoscope pipeline and performed EUS, recording results such as lesion size, shape, boundary, echogenic intensity and hierarchical origin, depth of infiltration, and the presence or absence of local lymph node metastasis.
1.3.3 Surgical method
A submucosal injection was completed to determine whether endoscopic surgery was appropriate according to the uplift signs of the lesions. The operation process (Figure 1) was as follows: First, (1) the submucosal injection was performed at the base of the lesion, and the lesion was fully lifted; then, (2) a KD-612L IT nano-knife was used to open the lateral edge of the lesion to avoid injury to the muscular layer. Next, (3) after the edge of the lesion was completely cut open, the lesion was encircled with a snare, and (4), after observing all the lesions, the snare was tightened and the diseased tissue was removed with electricity. Subsequently, (5) the wound was rinsed with normal saline to observe whether there was residual lesion and hemorrhage, and hot biopsy forceps were used to stop any bleeding and hemostatic clips were retained to close the wound to prevent delayed bleeding and perforation. Finally, (5) a pin was affixed along the edge of the lesion, the integrity of the incision edge was observed, the size of the lesion was measured and recorded, and the lesions were fixed with formalin solution and sent for pathological analysis.
1.3.4 Postoperative care
Patients were asked to fast for 48 hours after surgery, with water given after 24 hours. Hemostatic drugs, circulatory fluids, and antibiotics were administered. We closely observed each patient's abdominal condition, vital signs, and stool color.
1.3.5 Evaluation and follow-up
The surgical procedure; complete tumor resection rate; and postoperative complications such as perforation, bleeding, abdominal pain, and infection were evaluated. Colonoscopy was performed at three, six, and 12 months after surgery to observe the wound healing and ascertain the recurrence rate.