A hiatal hernia is a herniation of abdominal contents into the chest cavity. Usually this occurs through the esophageal hiatus or opening where the esophagus passes through. Most commonly the hernia involves portions of the stomach but can include any of the abdominal contents to include colon, fat, and abdominal organs. This type of hernia occurs most commonly as one ages.
The most common type is called sliding where the hernia reduces or goes away when you stand. The junction of the stomach and esophagus is displaced upwards. The rolling type of hernia is where the stomach herniates into the chest but the junction of the stomach and esophagus are in a normal location. There are mixed types, and those that include other herniated abdominal contents.
The hiatal hernias are common findings on imaging exams such as esophogram. They can be small and asymptomatic to large and symptom causing to include chest pain, pain in the upper abdomen, reflux, nausea and vomiting. The most feared complication is when the stomach in the hernia twists and causes a blockage and cut off of blood supply.
On esophogram, you can see a piece of the stomach going above the diaphragm as in the image below. The esophogram can also characterize whether it is a sliding or rolling type based on the position of the junction of the stomach and esophogram. The esophogram can not however tell if there are other herniated contents. A CT scan is needed for that.
Those hernias which are large or symptomatic are often treated surgically. I see a lot of pre operative esophograms where the surgeon may want to get a better look at the hernia. If you develop pain, then it is important to get prompt treatment as there may be a complication. In all cases, it is important to have your hernia assessed and possibly treated by a surgeon. You should discuss your particular case with your doctor to find the best way to address it.