This is a single-center, randomized controlled trial to evaluate whether subcutaneous closed-suction drainage would decrease the incidence of poor surgical site healing in lower gastrointestinal open surgery. The independent risk factors of the incidence of poor surgical wounds healing in lower gastrointestinal open surgery will be analyzed.

Inclusion Criteria:

• aged 18-85 years old, male or female
• all patients underwent lower gastrointestinal surgery: the digestive tract below Treitz ligament was called lower gastrointestinal tract, including jejunum, ileum, ileocecal part and colorectal
• open surgery (instead of laparoscopic) required
• willing participated in clinical verification and signed informed consent.

Exclusion Criteria:

• laparoscopic surgery
• upper gastrointestinal surgery (esophagus, stomach, duodenum and hepatobiliary pancreas)
• simple appendectomy / total appendectomy
• hernia surgery and intestinal obstruction surgery without intestinal resection
• infection of incision site before operation
• pregnant women
• expected death within 1 month after operation.

Export of individual patient data is not permitted by Chinese laws