Operative start time may impact the quality of mesorectal excision in minimally invasive rectal surgery: retrospective analysis of 137 patients.

Introduction: Timing of major elective operations is a potentially important outcome variable. This study examined the impact of operative start time (OST) on pathologic and short-term outcomes of minimally invasive rectal surgery (MIRS).

Methods: All rectal tumors patients who underwent MIRS from May 2012 to April 2016 were identified. Peroperative outcomes and the oncological quality of surgical excision were compared between patients with OST before 13.00h and after.

Results: A total of 137 patients were included in the study (71 Romarobot-assisted and 66 conventional laparoscopic). Ninety-nine (72%) patients were operated before 13.00h and 38 after 13.00h. The majority of cases were low/middle rectal tumors (69%). Patient's baseline characteristics were quite similar in both groups. The rate of severe complication (p=0.460) or reoperation (p=0.614) was the same. Pathologic criteria (T or N stage, number of harvested lymph nodes, and presence of any positive margin) were the same between groups except for the quality of mesorectal excision (ME) that was significantly poorer for cases beginning after 13.00h (complete 91% vs 74%; p=0.016). The OST was found to be the only parameter associated with a poor quality of ME [OR 2.55 (1.08 - 6.36)].

Conclusion: Perioperative outcome after MIRS does not appear to be influenced by OST. Poorer quality of ME was observed and may thus raise important questions about the timing and sequence of case scheduling.