The earliest clinical manifestations of patients with mechanical intestinal obstruction are abdominal pain, abdominal distension, nausea and vomiting, and stopping anal defecation. 1. Abdominal pain, abdominal distension: this is because mechanical intestinal obstruction causes intense peristalsis above the site of intestinal obstruction, manifesting persistent abdominal pain, usually high intestinal obstruction abdominal distension to a slight extent, and low intestinal obstruction causes abdominal distension obviously. 2. Nausea and vomiting: after the occurrence of intestinal obstruction, the higher the site of intestinal obstruction, the earlier and more frequent the nausea and vomiting, the lower the site of intestinal obstruction, the later the intestinal obstruction, the less obvious. 3. Anus stops defecation: patients with complete intestinal obstruction usually stop defecating. If patients have gastrointestinal discomfort, they should go to the hospital in time for examination and avoid carelessness, so as not to delay treatment and affect the therapeutic effect.