Efficacy of the modified anvil grasper for laparoscopic intra-corporeal circular stapled anastomosis.

The traditional anvil grasper may be difficult to use for connecting the stem of an anvil with the centre rod of a circular stapler because the grasper holds the anvil completely still. In addition, the head angle is fixed and cannot handle the anvil head delicately in a tight pelvic space. Many surgeons use a grasper designed for holding the bowel or a dissector for holding the anvil during intra-corporeal circular stapled anastomosis during low anterior resection, sigmoidectomy, left hemi colectomy and know that it is difficult to connect segments with these instruments due to slipping. A new modified anvil grasper was developed with curved blades that can easily grasp the stem of an anvil and smoothly connect it with the centre rod of the circular stapler. This grasper should be useful for surgeons performing laparoscopic intra-corporeal circular stapled anastomoses, which are the most challenging part of laparoscopic colorectal surgery.

INTRODUCTION

Intra-corporeal anastomoses during laparoscopic low anterior resection or sigmoidectomy, left hemi colectomy for colorectal cancer are performed using a circular stapler.[12] The traditional anvil grasper is often difficult to use for connecting the stem of the anvil with the centre rod of a circular stapler, because the grasper holds the anvil completely still. In addition, the head angle is fixed and cannot handle the anvil head delicately in the tight pelvic space. The grasper was modified to simplify the process of circular stapled anastomosis.

DESIGN OF THE NEW ANVIL GRASPER

The 22 mm straight blades of the normal grasper were curved 15 mm from the tip to create a 6 mm grasping surface that is the same diameter as the anvil stem with pliers by us carefully [Figures 1a–c]. The blades can grasp the stem without slipping and are easy to control [Figure 1d]. The new grasper allows a surgeon to hold the proximal colon in the ideal position and smoothly join the segments and perform the anastomosis, which are the most challenging tasks in laparoscopic colorectal surgery [Figure 2].

Figure 1

(a) Fully opened position of the jaw, (b) Blades are bent to form a 6 mm grasping surface, (c) Closed position of the jaw, (d) The stem of the anvil is grasped at any angle

Figure 2

(a) The stem of the anvil is easily caught by the anvil grasper. The proximal colon is easily held in the ideal position, (b) The anvil is smoothly connected to the centre rod of circular stapler

DISCUSSION

Laparoscopic colorectal surgery has become more common as the number of trained surgeons has increased. Although the incidence of anastomotic leakage for laparoscopic colorectal stapled anastomosis is no worse than that for open surgery,[3] anastomotic leakage should be avoided and the anastomosis procedure must be precisely completed. Many surgical videos show that even expert surgeons occasionally choose to use a grasper designed to hold the bowel or a dissector rather than the anvil grasper when they connect the stem of the anvil with the centre rod of the circular stapler. Performing intra-corporeal anastomosis in the tight pelvic space requires the fine control of the anvil head. However, the traditional anvil grasper cannot handle the anvil head delicately due to the shape and confined space. Therefore, many surgeons have to use a grasper designed for holding the bowel or a dissector. However, it is difficult to connect segments with these instruments due to slipping. When the stem of the anvil is held by a grasper designed for the bowel or a dissector, the force of the two blades act apically and apply the wrong type of force, based on the Parallelogram Law[4] [Figure 3a]. Increases the force applied to the grasper, also increases the apical force. This can cause the stem of the anvil to slip through the grasper. On the other hand, the grasping force of the new grasper does not generate apical force not occur [Figure 3b]. This simplifies grasping the stem of anvil any at any angle, and allows the surgeon to easily handle the proximal colon and smoothly connect it with centre rod of the circular stapler. This grasper should be very helpful for surgeons to perform laparoscopic intra-corporeal circular stapled anastomosis in the tight pelvic space. We plan to collaborate with a manufacturing company to produce and market this new type of grasper based on our design.

Figure 3

(a) When the stem of the anvil is grasped by a grasper designed for the bowel or a dissector, the forces (F1 and F2) from the blades act apically (FR) and exert force apically, based on the Parallelogram Law, (b) Grasping the stem of the anvil with the new anvil grasper, yields only an opposing force