Prospective multicentre observational study of natural orifice specimen extraction in minimally invasive colorectal surgery in the Asia-Pacific: protocol for the AP-NOSES registry.

Abstract

Natural orifice specimen extraction (NOSE) enables removal of colorectal surgical specimens through transanal or transvaginal routes while avoiding an abdominal extraction incision. Existing studies suggest potential benefits, including reduced wound morbidity and faster postoperative recovery. However, current evidence remains limited by retrospective designs, heterogeneous patient selection, variable extraction strategies and inconsistent assessment of long-term abdominal wall and patient-reported outcomes. The Asia-Pacific Natural Orifice Specimen Extraction Surgery (AP-NOSES) registry was established to prospectively evaluate clinical, abdominal wall and patient-reported outcomes following minimally invasive colorectal surgery involving natural orifice specimen extraction. AP-NOSES is a prospective multicentre observational registry coordinated by Singapore General Hospital. Consecutive adult patients undergoing elective minimally invasive colorectal resection with planned intact specimen extraction will be enrolled. The primary comparative analysis will be conducted within a predefined NOSE-eligible cohort comparing planned natural orifice specimen extraction with planned transabdominal specimen extraction. The registry aims to recruit approximately 800 patients across participating centres.The primary outcome is time to incisional hernia within 24 months following index surgery, with extraction-site incision type recorded and accounted for in the analysis. Secondary outcomes include postoperative morbidity, surgical site infection, extraction-site morbidity, length of hospital stay, patient-reported quality-of-life and functional outcomes, local recurrence, distant recurrence and disease-free survival.Patient-reported outcomes will be assessed using validated instruments including the EuroQol 5-Dimension 5-Level questionnaire, Body Image Scale and Low Anterior Resection Syndrome score. Data will be prospectively collected using a secure centralised REDCap database. Ethics approval has been obtained from the SingHealth Centralised Institutional Review Board (2026-0237). Findings from the registry will be disseminated through peer-reviewed publications and scientific conference presentations. NCT07615036.