The presentation varies from one period to another. In the acute phase, patients mainly present with severe abdominal and chest pain, respiratory distress or traumatic shock; in the latent phase, they are mostly asymptomatic or have only mild gastrointestinal symptoms such as abdominal distention and nausea; in the obstructive or strangulated phase, they present with sudden epigastric pain, nausea and vomiting, and in severe cases, abdominal muscle tonicity and abdominal distention, with symptoms of respiratory and circulatory compression, which can lead to death quickly if not diagnosed and treated promptly.