This retrospective cohort study evaluated whether supervised trainee involvement in highly specialized rectal surgery affects intraoperative safety or short‑term postoperative outcomes. The authors analyzed 573 consecutive elective procedures performed at a Swiss high‑volume academic centre between 2014 and 2023, including low anterior resection (LAR), abdominoperineal resection (APR), and ileal pouch–anal anastomosis (IPAA). Procedures were classified as “expert‑led” or “teaching” a fellow under direct consultant supervision when >75% of the operation was performed by the trainee. After 1:1 propensity score matching for key demographic and clinical variables, 374 patients remained (187 per group), with well‑balanced baseline characteristics.
Intraoperative outcomes were comparable between groups. Intraoperative adverse events (IAEs) occurred in 16% and 17% of expert‑led and teaching procedures, respectively (p=0.9). Operative time, blood loss, transfusion rates, conversion to open surgery, and creation of a protective ostomy showed no significant differences. Postoperative morbidity was also similar: overall complications occurred in 43% of expert-led versus 46% of teaching cases, and severe complications (Clavien–Dindo ≥IIIb) in 16% versus 17% (all p>0.05). Thirty‑day mortality was low (1.1% vs. 0%). Teaching was neither associated with overall morbidity (OR 0.60, 95% CI 0.30–1.17) nor severe complications (OR 0.64, 95% CI 0.26–1.48).
Multivariable analysis identified patient factors, not teaching, as drivers of adverse outcomes. Higher ASA class and immunosuppression were independent predictors of morbidity, while robotic surgery was associated with significantly lower postoperative complications. Severe complications were linked to ASA >2 and open surgery.
Overall, the study provides robust evidence that closely supervised trainee participation in complex rectal surgery does not compromise perioperative safety. These findings support the integration of structured teaching into high‑volume colorectal units, reinforcing the dual mission of maintaining excellent clinical outcomes while training future specialists.
Interview with Prof. Fabian Grass (CHUV)
What inspired you to conduct this study?
Rising healthcare costs and the well-established correlation between surgical volume and improved outcomes have led to the centralization of highly specialized medical (HSM) procedures, including deep pelvic rectal resections, within high-volume centers such as ours. This strategy aims to increase and concentrate institutional caseloads in order to improve outcomes and foster supervised surgical training programs. Furthermore, training of the next generation of colorectal surgeons remains a core mission of high-volume teaching facilities to ensure continuity of surgical care.
To date, no analysis exclusively focused on HSM rectal procedures. This gap is relevant given the associated technical complexity and potential risks and challenges, while the effects of trainee involvement on perioperative and functional outcomes remain unclear. Simon Cheseaux, a medical student at the University of Lausanne, was particularly interested in this topic, allowing him to complete his master's thesis, after observing several HSM procedures in the operating room.
Were there any unexpected findings?
One of the most interesting findings was the protective effect of the robotic platform. While we intuitively knew that the robot facilitated both navigation in deep and narrow spaces and surgical teaching thanks to the double console, proving it through robust institutional data was important to justify further implementation of robotic platforms into our clinical practice. This will not only benefit our patients – the study also helped demonstrate advantages to the hospital administration.
The finding of similar outcomes in expert-led and teaching procedures was important to us, implying that patients’ safety is not compromised when younger colleagues are trained under direct supervision. Looking closer at the results, we also found that there remains a selection bias (despite matching) regarding very low and more advanced tumors, which were mainly carried out by the expert surgeons.
What is the direct impact on the surgeon’s work?
It was important to prove that teaching the next surgical generation does not compromise patient outcomes. The results of this study help refine surgical teaching further by entrusting trainees with more challenging surgical steps, adapted to their surgical skills level. This is even more important in an era where centralization will lead to a higher case load of HSM procedures.
What is your learning point from this project?
Standardization of procedure steps and a “common language” among surgical consultants are key factors. We aim to provide trainees a structured and repeatable framework to perform challenging procedures. The results of this study help us to further develop and implement surgical teaching into our clinical practice, trusting that patient safety is not compromised. Dedicated fellowship programs will be further developed to identify and train the next surgical generation.
Are there any subsequent projects planned?
Yes, several follow-up projects and related master theses are underway. A first one will focus on long-term oncological outcomes to assess oncological safety of rectal cancer surgery when comparing expert-led and teaching procedures. A second one will focus on outcomes over time in relation to technical innovations at our institution, to assess more specifically advantages related to the robotic platform.
