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Surgical procedureAll procedures were performed under sterile conditions by surgeons responsible for the assigned procedure. The pigs were administered isoflurane via inhalation for anesthesia. A laparoscopic AR was performed with colorectal end-to-end anasto-mosis with DST. The resected colon was the approximately 5 cm. The anal side of rectum was cut using the Endo GIA Reinforced Reload with Tri-Staple TechnologyTM or Endo GIA Reload with Tri-StapleTM (Medtronic, Minneapolis, USA). The anvil was extracorporeally set into the oral side of the sigmoid colon. The colorectal anastomosis was intracorporeally performed using the EEA Circular Stapler with DST Series TechnologyTM (Medtronic, Minneapolis, USA).Approach AThe animals, i.e., nine pigs were classified into two groups. The first was the PGA group. In this group, the anal side of rectum was cut using the Endo GIA Reinforced Reload with Tri-Staple Tech-nology. The PGA sheet was used, which was sand-wiched between the oral side of the colon and the anal side of the rectum in anastomosis (Figure 1). The second group was the nonPGA group. In this group, the anal side of rectum was cut using Endo GIA Reload with Tri-Staple. The PGA sheet was not used and was not sandwiched between the oral side of the colon and the anal side of the rectum in anastomosis. The measurement of RIP was performed using HANDY MANOMETER PG-100 102GPTM (Nidec Copal Electronics, Tokyo, Japan) in the rectum, intraluminally filling it to the point of just overflowing by injecting air after anastomosis and clamping the oral side of the colon (Figure 2).Approach BIn this approach, laparoscopic AR was performed in four pigs. Rectal transection was performed using Endo GIA Reinforced Reload with Tri-Staple Tech-nology in all pigs. In the first case, normal DST anastomosis was performed without using the PGA sheet. In the other three cases, the PGA sheet was extracorporeally attached to the anvil; subsequently, reinforced DST was performed (Figure 3(a)-(e)). After laparoscopic AR with DST, the clinical courses were observed for 1 week. Furthermore, second-look surgery was performed to observe the 474reinforcement in colon surgery, in which the bioab-sorbable felt was loaded on a linear stapler14). The initial study results were very promising, with no bleeding and no significant leakage in a short-term follow-up. More importantly, no adverse outcomes have been observed in almost 3 years of continuous use. Consten et al reported early results with this approach that showed a decreased incidence of hemorrhage and leakage after gastric surgery10). Nguyen et al demonstrated that the use of bioab-sorbable staple line reinforcement is safe and effec-tive in the prevention of intraoperative staple line bleeding and postoperative gastrointestinal hemor-rhage11). Several authors agree that the use of bioabsorbable felt as staple line reinforcement seems to be safe and may be useful in preventing AL, bleeding, and, potentially, intraluminal stenosis as well. The use of bioabsorbable staple line rein-forcement may play an important role in high-risk patients undergoing colorectal surgery, which include those who use steroids, have a longer intra-operative time, or have cancer, immunosuppres-sion, and contamination and other issues. However, Placer et al reported that bioabsorbable staple line reinforcement in colorectal surgery does not reduce the rate of pooled anastomotic complications15).A new, thinner (0.15 mm), reinforcement mate-rial constituted only from PGA (NEOVEIL; Gunze, Osaka, Japan) has been developed. This new type of sheet with only PGA allows a shorter absorption time, and the influence for tissue is less from this sheet. This study assessed the usefulness and safety of this new PGA sheet using the colorectal double stapling technique (DST) anastomosis during laparoscopic anterior resection (AR) via two approaches in animal models. Approach A involved the evaluation of usefulness, made by assessing the rectal intratissue pressure (RIP) after DST anastomosis. Approach B involved the evaluation of safety, made by assessing the clinical short-term outcomes of DST anastomosis with PGA sheet and evaluating histological findingsMaterials and MethodsEthics StatementThe miniature pigs were purchased from ZEN- NOH Nagano. The animal studies were approved by the Animal Review Board of Juntendo Univer-sity (Approval number: 1323).