Clinical cases of non-healing or delayed wound healing after benign anal disease are often encountered, and Crohn’s disease is diagnosed upon further examination, so what is Crohn’s disease? Crohn’s disease CD), also known as restricted ileitis, restricted enteritis, segmental enteritis and granulomatous enteritis, is an inflammatory disease of the intestine of unknown origin. The disease and chronic nonspecific ulcerative colitis are both collectively referred to as inflammatory bowel disease IBD). Crohn’s disease can occur anywhere in the entire gastrointestinal tract, but is more likely to occur in the terminal ileum and right hemicolectum. Abdominal pain, diarrhea and intestinal obstruction are the main symptoms, and there are extraintestinal manifestations such as fever and nutritional disorders. The course of the disease is prolonged, often recurrent, and not easy to cure. The etiology of Crohn’s disease is still unclear and may be the result of a combination of pathogenic factors. It is associated with immune abnormalities, infections and genetic factors. Patients with the disease often show abnormalities in both humoral and cellular immunity. 2/3 of patients have Mycobacterium avium paratuberculosis detected in their tissues, and metronidazole has some therapeutic effect on CD. All of these suggest that infection may play a role in the development of CD. There are significant racial differences and familial aggregation in the development of Crohn’s disease. In terms of incidence, Caucasians are more likely than Blacks, and monozygotes are more likely than dizygotes; studies have found certain genetic defects in the disease. It is also found that there are certain genetic defects in the disease, all of which suggest a certain genetic predisposition. The clinical manifestations of Crohn’s disease are diverse and are related to the location, extent, severity, and duration of intestinal lesions and the presence of complications. Typical cases have a slow onset in young adulthood, and the duration of the disease often ranges from several months to more than several years. The active and remitting phases vary in length and alternate with each other, with progressive progression in recurrent episodes. In a few cases, the disease is acute, with high fever, toxemia and acute abdominal manifestations, and is often associated with serious complications. Occasionally, extra-intestinal manifestations such as perianal abscess, sputum duct formation or arthralgia may be the first symptoms. Symptoms of the disease: 1. Diarrhea is more common and without pus, blood or mucus. 2. Pain in the right lower abdomen. Postprandial abdominal pain is associated with gastrointestinal reflexes. 3, fever caused by active intestinal inflammation and absorption of toxins after tissue destruction, often intermittent. 4, abdominal masses are mostly located in the right lower abdomen and around the umbilicus and are easily confused with abdominal tuberculosis and tumors. 5.Small amount of blood in the stool. Other manifestations include nausea, vomiting, poor appetite, weakness, slightly thin, anemia, hypoalbuminemia and other nutritional disorders and extra-intestinal manifestations as well as clinical manifestations caused by complications. Ancillary tests for Crohn’s disease: 1. Whole gastrointestinal tract imaging: to understand the lesion and scope of the terminal ileum or other small intestine. It shows inflammatory lesions of the gastrointestinal tract, such as fissure ulcers, pebble signs, pseudo-polyps, single or multiple strictures, phlegmon tube formation, etc. The lesions are segmentally distributed. 2.Barium enema: It helps to diagnose colonic lesions, and double air-barium angiography can improve the diagnosis rate. 3.Standing abdominal plain film: dilated intestine and extra-intestinal mass can be seen. 4.Abdominal CT: thickened intestinal wall and separated intestinal collaterals can be seen, and it has some value for differential diagnosis with intra-abdominal abscess. Colonoscopy and mucosal biopsy: different manifestations of mucosal congestion, edema, ulceration, narrowing of the intestinal lumen, pseudo-polyps formation and oval signs are seen. The lesions are leap-frogged. 6. Ultrasound endoscopy helps to determine the extent and depth of lesions and to detect intra-abdominal masses or abscesses. In summary, the above examination methods or colonoscopy and mucosal biopsy integrated small bowel imaging of jumping lesions can be clearly diagnosed.