Hiatal Hernia

Hernias occur when one part of the body protrudes through a gap or opening into another part. And although a hernia can theoretically develop almost anywhere, most are in the abdominal area. This includes hiatal hernias — also known as diaphragmatic hernias — which form at the opening in your diaphragm where your food pipe joins your stomach.
Most small hiatal hernias don't cause any problems, and you may never know you have a hiatal hernia unless your doctor discovers it when checking for another condition. But a large hiatal hernia can allow food and acid to back up into your esophagus, leading to heartburn and chest pain. Self-care measures or medications can usually alleviate these symptoms, although very large hiatal hernias sometimes need surgical repair.
Most small hiatal hernias cause no problems. But larger hernias may cause heartburn, belching or chest pain when stomach acids back up into your food pipe (esophagus). These signs and symptoms tend to become worse when you lean forward, strain, lift heavy objects or lie down, and they can also worsen during pregnancy.
In rare cases, the part of your stomach that protrudes into your chest cavity may become twisted (strangulated) or have its blood supply cut off, leading to:
Severe chest pain
Difficulty swallowing (dysphagia)
Obstruction of your esophagus
Your chest cavity and abdomen are separated by your diaphragm — a large dome-shaped muscle that's responsible for a good part of normal breathing. Your esophagus passes into your stomach through an opening in the diaphragm. Hiatal hernias occur when the muscle tissue surrounding this opening becomes weak and the upper part of your stomach bulges through the diaphragm into your chest cavity. Anything that puts intense pressure on your abdomen — including persistent or severe coughing or vomiting, pregnancy, straining while going to the bathroom, or lifting heavy objects — can contribute to hiatal hernias.
A hiatal hernia in turn can cause or contribute to gastroesophageal reflux. This happens when a hernia slightly displaces the lower esophageal sphincter, a circular band of muscle around the bottom of the esophagus.
Ordinarily, the diaphragm is aligned with the lower esophageal sphincter, which relaxes to allow food and liquid to flow into your stomach when you swallow. The diaphragm supports and puts pressure on the sphincter to keep it closed when you're not swallowing. But a hiatal hernia raises the sphincter above the diaphragm, reducing pressure on the valve. This causes the sphincter muscle to open at the wrong time, allowing stomach acid to flow up into the esophagus.
A hiatal hernia can also cause heartburn if the herniated portion of your stomach becomes a reservoir for gastric acid, which can then easily travel up your esophagus.