Crohn's disease is a chronic inflammatory transmural bowel disorder characterized by high rate of postoperative anastomotic complications and recurrences. Surgery itself can influence immunologic function and trigger inflammatory response, which may result in the flare of Crohn's disease soon after surgery (within one month), especially near the anastomosis. Early flare-up of Crohn's disease can negatively impact the outcomes of operation. However, due to the the complexity of perioperative period and dangerous of invasive examine, it is difficult to distinguish disease flare from postoperative complications.

In this study, the investigators aim to development a diagnostic method of flare-up within one month after surgery, which can help us to detect and then treat disease flare in time.

HBI score, serum CRP, ESR, WBC, Hb, PLT, IL-6，PCT and fecal Calprotectin will be monitored within one month after resection.

Inclusion Criteria:

• patients undergoing intestinal resection of all macroscopic disease, with an endoscopically accessible anastomosis,

Exclusion Criteria:

• patients have an anastomosis which is endoscopically inaccessible by standard colonoscopy;
• patients withs persisting macroscopic abnormality after surgical resection;
• patients with an end stoma (ileostomy or colostomy);
• patients are not suitable to undergo endoscopy because of co-morbidities or an unwell clinical state;
• patients who are unable to give informed consent;
• patients who are pregnant

Adult patients with Crohn's disease