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(a) Histological findings (hematoxylin and eosin stain). (b) Anastomosis of the control case. (c) Anastomosis with the PGA sheet, with obvious remaining PGA material. (d) The PGA sheet is represented as the space between the arrows.478strate statistical difference. The results of our approaches were the higher credibility because we had used the big animal like pigs. Animal studies with a larger sample size are too difficult to continue ethically. Our results suggested that this approach was risk-free. In the future, we plan to conduct a study that confirms the PGA sheet’s effectiveness in humans. The RIP was dependent on the resting pressure of the anus; hence, the resting pressure of the anus should be measured to obtain more accu-rate data. Multiple RIP measurements should be made for reproducibility. However, in our study, we measured the RIP only at the point when the injected air had just overflowed. The anastomosis was broken only during one measurement, and we had only one chance of measurement per anasto-mosis. The duration of follow-up was short (1 week), whereas ALs may be detected anywhere from 3 to 45 days postoperatively17, 18). In addition, there appears to be two peaks of when the diag-nosis is made of anastomotic leaks. When leakages observed clinically, the median postoperative time of diagnosis is 7 days; when leaks are diagnosed radiographically, the median postoperative time is 16 days8). In this approach, anastomotic leaks were assessed by only clinical findings. None of the pigs had clinical complications associated with anasto-mosis failure; therefore, the authors posited that short-term outcomes of AR might be acceptable. The other key histological finding was the abscess formation in one pig in approach B. In approach B, the PGA sheet was set intrarectally for attaching it to the mucosal surface, not within the tissue. Although there was no PGA sheet in the abscess, this finding showed that the PGA was able to lead to surgical site infection. Few studies have reported that the PGA sheet was attached to the mucosal surface19). However, they did not report the histo-logical findings. To our knowledge, our report is rare in that the PGA sheet in our study was attached to the mucosal surface of the anastomotic site of the circular stapler and assessed on the basis of histological findings. The relationship between with the clinical findings and abscess formation was unclear and must be verified. Finally, the loca-tions of the PGA sheet in these two approaches were different. In approach A, the method to use the PGA sheet was the simplest, in which it was sandwiched between the oral and the anal side. In approach B, we considered using two PGA sheets, similar to the more clinical Endo GIA Reinforced Reload with Tri-Staple Technology (Figure 3(f)). Figure 5　Histological findings of anastomosis (Approach B)