2.1. Subject Selection

This retrospective study was approved by the ethics committee of the First Affiliated Hospital of University of Science and Technology of China (USTC, NO 2022-ky-279). A total of 40 cases from hospitalized patients (28 males and 12 females) were collected in the First Affiliated Hospital of USTC between August 2021 and August 2022. These cases were patients diagnosed with CD based on a combination of standard criteria that included clinical symptoms, physical examination, colonoscopy/double-balloon endoscopy (DBE), imaging (CTE or MRE), and histopathology. In addition, all patients joined this study with written informed consent for the research use of their clinical data. The Helsinki Declaration guidelines were followed.

(1) According to ECCO-ESGAR Guideline [10], the patients who were diagnosed with CD and completed colonoscopy/DBE, IUS examination, blood routine, ESR, and CRP. All data were collected with a maximum interval of 1 month. (2) Age ≥ 14 years, age ≤ 70 years.

(1) Patients suffer from local or systemic infection. (2) CD isolated with the upper gastrointestinal tract. (3) Patients treated with colon resection and terminal ileum resection, which may result in altered visceral adiposity and IUS parameters. (4) The most severe intestine in the rectum, (5) BMI ≥ 30 kg/m². (6) Pregnancy. (7) Patients treated with prednisone and azathioprine, which may result in altered blood inflammatory markers