Swelling below the left side of the navel may be caused by gastrointestinal dysfunction, intestinal obstruction, pelvic inflammatory disease and other diseases. 1. Gastrointestinal dysfunction: Gastrointestinal dysfunction is caused by the interaction of biological, psychological, and social factors, and patients will experience abdominal pain, diarrhea, constipation, nausea and other symptoms, which can lead to distension below the left side of the navel. 2. Intestinal obstruction: distension below the left side of the navel may also be caused by intestinal obstruction, intestinal obstruction is a variety of reasons for the obstruction of the passage of intestinal contents, the main causes include tumors, intestinal adhesions, etc., the patient will experience abdominal pain, constipation, vomiting, anus to stop defecation and other symptoms. If the intestinal tract below the left side of the navel is obstructed, the local gas can not be discharged, and flatulence will occur. 3. Pelvic inflammatory disease: Pelvic inflammatory disease is an infectious disease of the upper reproductive tract of women, patients will have lower abdominal pain, fever, increased vaginal discharge and other symptoms, some patients will feel bloating. The cause of the disease is related to pathogen infection, and sexually active women are prone to it. There are more causes of distension below the left side of the navel, so it is recommended to consult a doctor for a clear diagnosis.