1. Institute of Anal-Colorectal Surgery, No. 150 Central Hospital of PLA, Luoyang, Henan, China
2. The General Hospital of Jinan Military Region, Jinan, Shandong, China
3. Clinical Laboratory of the First People's Hospital of Luoyang, Luoyang, Henan, China
4. Department of Ultrasound, General Hospital of Beijing Military Region, Beijing, China