Development and validation of a transanal endoscopic rectal purse string simulator

Rectal purse string placement for transanal mesorectal excision is challenging, and practice is difficult. The objective of this study is to build an endoscopic rectal purse string simulator and provide evidence for the validity of its use.

A low-cost transanal endoscopic rectal purse string simulator was created and used to measure the performance of participants. Participants included general surgery residents, fellows, and staff surgeons from several Canadian university-affiliated institutions across Canada. The performance of the rectal purse string placement was measured by the time to completion of the task as well scoring with a modified objective structured assessment of technical skills (OSATS) score and a modified advanced laparoscopic suturing (ALS) score.

Thirty-nine participants were recruited into the study. Participants were split into three groups, based on prior experience with laparoscopic suturing, for the analysis of suturing a rectal purse string on the simulator based on three performance measures. There was a significant difference found in all three measures of performance in the three groups (time to completion p = 0.014, mean blinded OSATS score p = 0.007, mean blinded ALS score p = 0.020). Participants with previous laparoscopic suturing had significantly faster times to completion and higher skills scores when compared to residents (time: 5.1 ± 1.4 min vs 9.0 ± 4.8 min, p = 0.005; OSATS: 19.7 ± 2.8 vs 13.0 ± 5.8, p = 0.00398, ALS: 27.4 ± 4.0 vs 18.9 ± 8.5, p = 0.0151).

A transanal endoscopic purse string simulator was constructed and preliminary testing has shown variable performance based on prior laparoscopic suturing experience.