48: Laparoscopic trocar insertion: A comparison of insertional and rotational forces between expert and novice surgeons


      More surgical complications occur during laparoscopic entry into the peritoneal cavity then with any other step in surgery. Learning how to safely perform laparoscopic entry has traditionally been through the “see one, do one, teach one” method and mastery gained through in vivo surgical experience. In order to better understand the training needs of novice surgeons, we sought to characterize differences in force and torque applied to the abdominal wall between expert and novice surgeons during laparoscopic trocar insertion.

      Materials and Methods

      This IRB-approved study was performed in August 2017 at an academic medical center in the department of obstetrics and gynecology. Twenty-nine subjects were recruited to participate in this study, including: 14 novices (medical students and new interns), 7 residents, 3 fellows (MIGS, REI, Gyn Onc), and 5 experts (gynecologic surgery faculty). Using a 6-axis force torque sensor (Nano-17, ATI Inc., Apex, NC) mounted to a 5-mm Kii Fios Trocar (Applied Medical, Rancho Margherita, CA), participants were asked to make a 5-mm incision through a silicone skin layer then perform entry though a simulated abdominal wall made by Applied Medical, Inc. with anatomically correct layers corresponding to the tissue layers of the anterior abdominal wall and mounted to a laparoscopic box trainer. Axial forces, torques, and frequency spectra were measured and compared using ANOVA.


      Mean axial force, a direct measurement of insertional force, was higher in novices than experts (3.53 vs. 4.98 N, p = 0.03). Mean variance of insertion force was also higher in novices (3.63 vs. 4.80 N, p = -0.03). Maximum insertion forces were not different between experts and novices (12.1N vs. 13.9 N, p = 0.33) nor was maximum (50.9 vs. 50.3 N, p = 0.93) and mean rotational force (10.2 vs. 12.2 N, p = 0.62). Total insertion time (2.57 vs. 3.57 seconds, p = 0.19) was not different between experts and novices.


      For laparoscopic entry through a simulated abdominal wall, insertional forces, but not rotational forces, were significantly different between experts and novices. Novices consistently demonstrated higher insertional forces as well as greater variation in insertional force throughout the process of trocar placement. Further studies of insertional metrics, including force and rotational measurement in vivo, may help to define safer patterns of trocar placement and thus establish objective methods for teaching safe laparoscopic entry.