Surgical Site Infection Outcomes in Natural Orifice Intracorporeal Anastomosis and Extraction (NICE) Procedure - The NICE Trial

Background and Rationale The Natural Orifice Intracorporeal Anastomosis and Extraction (NICE) procedure represents an emerging innovation in minimally invasive colorectal surgery. It combines robotic intracorporeal anastomosis (ICA) with natural orifice specimen extraction (NOSE), typically transrectal, to avoid the need for an abdominal extraction incision. This approach may reduce surgical site trauma, postoperative pain, opioid use, and rates of incisional hernias.

Intracorporeal anastomosis has been widely studied in right-sided colectomies, with consistent evidence showing reduced surgical site infections (SSIs) and improved recovery. However, application to left-sided resections introduces unique challenges. The bacterial density in the left colon and rectum, combined with transrectal manipulation, may increase the risk of deep or organ-space SSIs. While early single-center experiences suggest the NICE procedure may be safe and effective, multicenter validation in a broader clinical setting is needed.

Study Objectives The primary objective of this study is to determine the 30-day incidence of surgical site infections (superficial, deep, and organ-space) in patients undergoing robotic left-sided colorectal resections using the NICE procedure. Secondary objectives include assessment of intraoperative technical performance, perioperative complications, postoperative recovery, and longer-term functional and quality of life outcomes.

Study Design This is a prospective, multicenter, observational cohort study enrolling patients undergoing elective robotic-assisted left colectomy or rectosigmoid resection for benign colorectal disease. All procedures will use the standardized NICE technique. Participating surgeons must have performed at least 20 prior NICE procedures. The study will run over a 24-month accrual period, with each patient followed for at least 6 months postoperatively.

Study Procedures Surgical intervention involves robotic left-sided resection with intracorporeal anastomosis and transrectal specimen extraction. All sites will follow a standardized Enhanced Recovery After Surgery (ERAS) protocol tailored to robotic colorectal surgery. Operative videos will be collected for quality control, ensuring adherence to the defined NICE procedural steps.

Postoperative follow-up includes in-person or remote assessments at 30 days, 3 months, and 12 months. Functional outcomes will be measured using validated questionnaires: Wexner score for fecal incontinence, LARS score for bowel dysfunction, and PROMS-10 for health-related quality of life.

Data Collection and Oversight Clinical data will be collected prospectively using REDCap, a secure, HIPAA-compliant electronic data capture system. All patient data will be pseudonymized. A centralized coordinating center will oversee data integrity, standardization, and site compliance. Surgical cases will be video recorded to ensure procedural fidelity.

Each site must consecutively enroll eligible patients and maintain compliance with protocol-defined ERAS standards. Surgeons will be credentialed based on review of unedited operative videos prior to participation.

Outcomes The primary outcome is the 30-day SSI rate, including superficial, deep, and organ-space infections. Secondary outcomes include intraoperative variables (e.g., operative time, blood loss, conversion rate), postoperative recovery (opioid use, length of stay, complications, readmissions, reinterventions), and long-term outcomes such as hernia formation and bowel function.

Patient-reported outcome measures will be collected preoperatively and at designated follow-up intervals. These include the Wexner score, LARS score, and PROMS-10, allowing for longitudinal evaluation of continence, function, and quality of life.

Sample Size and Statistical Considerations The study is powered to detect non-inferiority in SSI rates compared to conventional techniques. Assuming a historical SSI rate of 5% and a non-inferiority margin of 5%, a sample size of at least 224 patients provides 80% power with a 5% alpha. To accommodate multivariate modeling and variability across sites, the planned enrollment target is 300-400 patients.

Data will be analyzed using multilevel logistic regression to account for center and surgeon-level effects. Sensitivity analyses will be conducted to test robustness of findings. Descriptive and inferential analyses will be used to evaluate changes in quality of life and functional outcomes over time.

Significance This trial aims to provide high-quality evidence on the safety and performance of the NICE procedure for left-sided colorectal surgery. If non-inferiority is demonstrated, the findings may support broader adoption of this technique, with implications for faster recovery, reduced SSI risk, and improved patient experience. By incorporating video-based quality control and standardized ERAS pathways, the study ensures procedural consistency and real-world applicability of results.