There are two types of hiatal hernias--sliding and paraesophageal. Sliding hiatal hernias are the result of part of the stomach and the area that joins the stomach to the esophagus bulging up into the diaphragm and chest. Most sliding hernias are small in size. Symptoms are usually mild but may worsen when lying down or bending forward. A paraesophageal hiatal hernia involves a portion of the upper stomach but excludes the area that connects the esophagus and stomach. Either type of hiatal hernia can range in size and symptoms; however, paraesophageal hiatal hernias may have no symptoms, but when they do appear, tend to be more severe. Both types of hernias can be affected by other illness, frequent pressure on the abdomen, poor diet, and smoking.