The goal of this observational study is to learn if a new surgical technique, called the NICE procedure, is as safe as standard methods for treating benign left-sided colon and rectal diseases in adults. The main question it aims to answer is:

Does the NICE procedure lead to similar or lower rates of surgical site infections (SSIs) within 30 days compared to traditional surgery?

Researchers will gather information from hospitals across the country to evaluate how well this procedure works when performed by experienced surgeons in everyday clinical settings.

Participants will:

Have surgery using the NICE procedure, which uses a robotic platform and removes the specimen through a natural opening (the rectum).

Be monitored for any infections or complications after surgery.

Complete surveys to track their recovery, bowel function, and quality of life for up to 6 months.

This study may help improve recovery, reduce pain, and lower infection risk in future colorectal surgeries.

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.

Inclusion Criteria

1. Diagnosis: Patients must be diagnosed with benign left-sided colon and rectosigmoid disease, including diverticulitis and benign colon neoplasia.

2. Age Requirement: Patients aged 18 years or older. 3. Cancer-Free: There must be no evidence of cancer or metastatic disease in the patients. This includes:

• Colonoscopy with no evidence of malignant lesion in the last 12 months

• CT scan with no concern for malignancy in the prior 6 months

• No other clinical concern for possible malignancy 4. Surgical Eligibility: Patients must be eligible to undergo robotic left colectomy with primary anastomosis without a planned diverting stoma.

  5. Informed Consent: Participants must be able to understand and willing to sign a written informed consent form.

  6. Treatment with NICE: Patients who undergo surgical treatment specifically with the NICE procedure.

  7. Surgeon Experience: The patients should be treated by surgeons who have performed at least 20 NICE procedures.

  8. General Practice Inclusion: Patients treated by surgeons who offer the NICE procedure as part of their general surgical practice and do not super-select patients for the procedure.

Exclusion Criteria

1. Urgent or emergent procedure

2. Patients diagnosed with cancer or metastatic disease are not eligible for the study. This includes:

   • Known genetic predisposition to colorectal cancer
   • First-degree family history of colorectal cancer
   • Any concern about colorectal cancer

3. Patients with an ongoing infection other than diverticulitis (e.g., pneumonia) or taking antibiotics unrelated to diverticulitis.

4. Patients with a history of pelvic radiation

5. Patients with prior anorectal surgery or prior colorectal surgery

6. Patients with fecal incontinence, outlet obstructive defecation, anismus, or levator spasm at baseline are excluded from the study

7. Any procedure in which a primary anastomosis is not feasible or diversion of the fecal stream is anticipated

8. Patients with a high ASA of 4 or more and clinical frailty score of 8 or more

9. Patients requiring preoperative nutritional support, such as total parenteral nutrition (TPN) or enteral feeding via percutaneous endoscopic gastrostomy (PEG) or nasogastric (NG) tube within 30 days prior to surgery

10. Systemic steroids used within the last 12 months or immunomodulators and biological agents used within the last 60 days prior to surgery will render the patient ineligible for the trial.

    • Preoperative antibiotics used within two weeks to treat diverticulitis are permitted.
    • Antibiotics used within 30 days before surgery for any condition other than treating an infection related to diverticulitis will render the patient ineligible for the trial.

11. Regional block anesthesia (e.g., epidural and spinal) is not permitted in this trial.

12. Chronic Opioid Use: Chronic use of opioids in the prior 3 months.

Participants will be recruited from multiple high-volume colorectal surgery centers across the United States that routinely perform robotic-assisted procedures. All participating sites follow a standardized Enhanced Recovery After Surgery (ERAS) protocol and are required to have surgeons experienced in the NICE procedure. The study population will consist of patients scheduled for elective robotic left-sided colectomy or rectosigmoid resection for benign disease, treated in real-world, non-super-selected surgical practice settings.

Individual participant data (IPD) will not be shared outside the study team due to privacy concerns and the multicenter observational nature of the study. Although data are pseudonymized, the complexity and volume of surgical video and clinical data could still risk indirect identification. Data access is restricted to investigators approved by the study's steering committee to ensure confidentiality and ethical compliance.