Yongshun Gao1, Yunfei Zhang2, Hailin Feng2, Yukun Zhang2. 1. Department of Gastrointestinal Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China. Email: 542520679@qq.com. 2. Department of Gastrointestinal Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China.