Gastro-oesophageal reflux, also known as acid reflux, may occur when the stomach contents reflux up into the esophagus and/or mouth. Reflux is a normal process that occurs in healthy infants, children, and adults. Most episodes are brief and do not cause bothersome symptoms or complications. In contrast, people with gastro-oesophageal reflux disease (GERD) experience symptoms as a result of the reflux. Symptoms may include heartburn, regurgitation, vomiting, and difficulty or pain with swallowing. The reflux of stomach acid may even affect the vocal cords causing hoarseness or even be inhaled into the lungs (called aspiration).
At the lower end of the oesophagus, where it joins the stomach, there is a circular ring of muscle called the lower esophageal sphincter (LES). After swallowing, the LES relaxes to allow food to enter the stomach and then contracts again to prevent the back-up of food and acid into the esophagus. Sometimes the LES relaxes intermittently allowing stomach content to reflux into the oesophagus. If these episodes are brief, then symptoms don’t really occur. Once these relaxation periods are prolonged and more regular, then a person can experience symptoms. The stomach acid present in the refluxate can cause damage to the oesophagus. Some people believe they ’have a lot of acid’. This isn’t the case, it’s just that the acid moves up into the oesophagus leading to bothersome symptoms.
The diaphragm is a large flat muscle at the base of the lungs that contracts and relaxes as a person breathes in and out. The oesophagus passes through an opening in the diaphragm called the diaphragmatic hiatus before it joins with the stomach.
If there is a weakening in the diaphragm muscle at the hiatus, the stomach may be able to partially slip through the diaphragm into the chest, forming a sliding hiatus hernia.
The presence of a hiatus hernia makes acid reflux more likely, but its presence is not necessary for reflux to occur. Hiatus hernias are more common in people over 50, in obesity and during pregnancy. For this reason it is advisable to try to lose a little bit of weight if your heartburn is associated with weight gain. Often heartburn worsens during pregnancy, especially in the third trimester due to abdominal pressure causing the LES to weaken.