A hiatal hernia is basically when the stomach comes up into the chest. To understand what a hiatal hernia is you need to understand what normal anatomy is. We have a diaphragm which is a muscle that separates everything in the chest, which has our lungs and our esophagus, from our abdominal cavity, which has our stomach, small intestine, ovaries, uterus, all of those organs in our abdominal cavity. Its job is to help keep the contents separate and also to help with breathing.
There's a small hole that is in the middle of the diaphragm which the esophagus goes through. If there is a small defect or a little tear in that diaphragmatic wall then the stomach can actually pop up into the chest so that you get a little bubble of the stomach that herniates up into the chest. So that's what a hiatal hernia is.
There is a multitude of symptoms that you can get afterwards, and most common is gastroesophageal reflux. The way the hiatal hernia develops is a little bit difficult. It could be that there's increased abdominal weight or increased abdominal pressure that causes the stomach to herniate up into the chest. So, if we want to treat that hiatal hernia we need to reduce the weight around our belly. In the worst case scenario we could have surgery in order to bring that stomach back down and make that defect in the diaphragm closed up.