There have been several trials to protect against rectal anastomosis leakage by scientists and colorectal surgeon. Ravo and Ger proposed using an intracolonic bypass tube to protect against rectal anastomosis leakage.(12) Ros tried several drainable tubes in colon anastomosis in rats and found that an intraluminal drainable tube improved survival compared to the control group.(13) A sterilized condom has also been used to protect the rectal anastomosis.(14) All of these trials aimed to prevent fecal contamination and decrease fecal loading, which may affect disruption of the intestinal anastomosis. Also, by using various different types of intracolonic bypass materials, they attempted to decrease the intraluminal pressure.(9, 10) A transanal tube showed decreased rectal pressure up to Postoperative Day 5.(15) A recent multi-center randomized trial from the Netherlands used a biodegradable drain called a C-seal affixed to the anastomosis line by a circular stapler.(16) However, the results were unsatisfactory, as 10% of cases demonstrated anastomosis leakage, 7.7% required re-intervention, and 5% of controls demonstrated anastomosis leakage. Problems related to the C-seal included detachment from the anvil, difficult stapler removal, and anal pain.
Learning from these previous studies, it was essential for us to devise a simplified method in order to protect the anastomosis without the use of a diverting stoma. We then went back to the beginning to create a concise intraluminal drainage tube.
Among several problems, we found that preventing rectal stent migration was most important. In practice, even in cases of stent placement to avoid obstructions in rectal cancer, stent migration is one of the most common complications.(17) The stent was maintained for no more than six days despite of its maximal width 36 mm and performing a laparoscopic intracorporeal stitch on a proximal stent and bowel. Also, to reduce anal pressure, a diet containing Colyte was used to induce the defecation of loose stool. These efforts were not as effective as we had anticipated as not all subjects could consume required dose of Colyte as humans could.
However, the subjects chosen were still considered to be the best animal to use in this experience since they cannot remove the stent themselves when compared to other mammals. All of the experimental subjects were sacrificed within Postoperative Day 7.
When considering the inconvenience of placing Rectal Stents in patients, and as rectal anastomosis collagen density is highest at one week postoperative,(18) seven day period appears to be the minimum requirement. However, all Rectal Stents were removed naturally within seven days for our experiment. Despite the encountering of the natural stent removal, there were no cases of gross anastomosis leakage seen on the water-air leak or barium leakage x-ray tests. For porcine no.11–13, we did not expect to find any gross leakage since subject’s stents were fixed with intracorporeal stitches. These results suggest stent safety in the bowel mucosa and anastomosis site despite insertion and detachment. Only two subjects demonstrated gross anastomosis leakage during and after surgery; however, neither demonstrated leakage on either leakage test.
Although our experiment encountered difficulties due to the natural stent removal, the proper stent placement in humans may be achieved. To our knowledge, so far, no trials have added perianal fixation of Rectal Stents to the experiment. The Rectal Stent developed by our team has a smooth vinyl component at the end with a sufficiently long length for affixing to the buttock area. The design to include narrow stent end diameter will also minimize perianal area irritation. Also, the vinyl is strong enough to not tear off easily. Although all stents in this study were removed naturally, it was not due to the strength of the vinyl, but due to fecal pressure.