The clinical symptoms of Crohn’s disease include abdominal pain, diarrhea, abdominal mass, fistula formation, and intestinal obstruction, which may be accompanied by fever, anemia, nutritional disorders, and extraintestinal damage to joints, skin, eyes, oral mucosa, and liver. The disease can recur and persist without healing.

      1. Digestive system performance

      (1) Abdominal pain is located in the right lower abdomen or around the umbilical cord. It presents cramping pain, with intermittent attacks, accompanied by bowel sounds, which aggravate after meals, and relieve after defecation. If the abdominal pain persists and the tenderness is obvious, it indicates that the inflammation spreads to the peritoneum or the abdominal cavity and forms an abscess. Actute total abdominal pain and tight abdominal muscles may be caused by acute perforation of the diseased intestine.

      (2) Diarrhea is caused by inflammation and exudation of the diseased intestine, increased peristalsis, and secondary malabsorption. Intermittent seizures started at the beginning, and persistent mushy stools without pus, blood, or mucus in the later stage. If the disease involves the lower part of the colon or rectum, there may be mucus, bloody stools, and tenesmus.

(3) Abdominal masses are more common in the right lower abdomen and around the umbilical cord. They are caused by intestinal adhesions, thickening of the intestinal wall and mesentery, enlarged mesenteric lymph nodes, internal fistulas, or local abscess formation.

      (4) Fistula formation is one of the clinical features of Crohn’s disease. Transmural inflammatory lesions penetrate the entire intestinal wall to extraintestinal tissues or organs, forming a fistula. Internal fistula can lead to other intestinal segments, mesenteric, bladder, ureter, vaginal retroperitoneum. The external fistula leads to the abdominal wall or perianal skin.

      (5) Perirectal lesions. A few patients have lesions such as fistulas, abscess formation, and anal fissures around the anus and rectum.