[Application of KeyPort access to transanal endoscopic mircrosurgery]

Objective: To explore the effectiveness of KeyPort access in transanal endoscopic mircrosurgery (TEM). Methods: A descriptive case series study was performed. Clinicopathological data of 20 patients undergoing KeyPort access TEM in Beijing Chaoyang Hospital of Capital Medical University from December 2016 to April 2018 were collected and analyzed retrospectively. Procedure of KeyPort access TEM: general anesthesia or combined spinal epidural anesthesia (CSEA); lithotomy or prone jack-knife position; anal dilation; placement of the KeyPortaccess; connection of TEM pneumoperitoneum device, light source and imaging equipment; placement of 5 mm dedicated endoscope; insufflation of CO2 with pressure of 1.6-2.0 kPa (12-15 mmHg); after rinsing the intestinal lumen, circular resection marginlabeled by the needle-shaped electrocautery;electric coagulation or ultrasonic knife used to perform a full-thickness resection with a 0.5 cm-1 cm margin along the marking line. Indications of KeyPort access TEM: (1) benign large sessile polyps which were difficult to resect under colonoscopy; (2) submucosal lesions with diameter <2 cm; (3) Tis and T1 stage rectal carcinoma without lymph node metastasis; (4) palliative resection of T2 stage rectal carcinoma without lymph node metastasis. Contraindications: (1) accompanying serious diseases without the tolerance of anesthesia and operation; (2) distance from lesion to anal verge >20 cm. Results: There were 10 males and 10 females with age of (63±15) years old and BMI of (24.5±3.3) kg/m(2). The diameter of the lesions was (2.0±1.3) cm, and the distance from lesion to anal verge was (6.2±2.2) cm. One patient had 3 lesions at different positions in rectum with diameters of 0.5 cm, 0.5 cm, and 1 cm, respectively. All operations were accomplished through the KeyPort access TEM and no case was transferred to other methods. The duration of surgery was 75 (30-220) minutes; intraoperative blood loss was 10 (0-30) ml. Two patients with rectal anterior wall lesions underwent full-thickness resection of the intestine wall reaching the peritoneal reflex with penetration into the peritonealcavity, and received suture closure immediately. For the patient with 3 rectal lesions, the 1.0 cm lesion received a full-thickness resection and the other 2 lesions received submucosal resection. No postoperative complication occurred. Postoperative pathology showed that there were 1 case of chronic inflammatory lesion, 4 cases of benign tumor, 3 cases of carcinoma in situ, 4 cases of neuroendocrine tumor, 6 cases of pT1 rectal cancer, 2 cases of pT2 rectal cancer (both invading the superficial muscle layer). The median hospital stay was 6 (3-7) days. The postoperative follow-up was (7.2±3.8) months. No postoperative complication or recurrence was observed. Conclusion: TEM with KeyPort access is safe, rapid and effective in the treatment of rectal tumors.