Abdominal drains are placed for abdominal surgery mainly for larger surgical wounds, which are prone to postoperative blood or fluid leakage, or for severe abdominal infections, where the patient has a drain placed to avoid residual abdominal infection. Generally, after abdominal surgery, if the abdominal drainage tube drains less than 10 ml of fluid for two consecutive days, it can be considered to be removed. However, with the advancement of medical technology and deeper understanding of medical level, even if the amount of abdominal drainage fluid does not exceed 10 ml for more than two consecutive days, further abdominal ultrasound is usually required to exclude the possibility of encapsulated fluid before removal of abdominal drainage tube is considered. Because it is difficult to drain the encapsulated fluid through the original drainage tube, abdominal puncture and drainage under ultrasound guidance is required to obtain a cure. Therefore, the timing of abdominal drainage tube removal depends on the purpose of placing the drainage tube and the different postoperative changes to determine its removal.