A hiatus hernia, also known as a hiatal hernia, is a condition in which a portion of the stomach and sometimes other accompanying organs protrude through the diaphragm into the chest cavity. The hiatus is an opening in the diaphragm through which the oesophagus passes before connecting to the stomach. When part of the stomach bulges through this opening, it can lead to discomfort and potentially cause symptoms such as heartburn, regurgitation, and difficulty swallowing.

Types of Hiatus Hernia 

There are two main types of hiatus hernia: sliding hiatal hernia and paraesophageal hiatal hernia. Sliding hiatal hernias are more common and occur when the junction of the oesophagus and stomach slides up into the chest. Paraesophageal hiatal hernias involve the stomach pushing up through the diaphragm next to the oesophagus. More complex hernias can include accompanying organs such as the colon also moving through the defect into the chest cavity.

Causes and Risk Factors
The exact cause of hiatus hernia is not always clear, but several factors may contribute to its development. Common causes and risk factors for hiatus hernia include:

1. Weakness in the Diaphragm: Age-related weakening of the diaphragm muscles, which support the lower esophageal sphincter (LES), can increase the risk of hiatus hernia.
2. Increased Abdominal Pressure: Conditions or activities that increase pressure in the abdomen, such as obesity, pregnancy, heavy lifting, or straining during bowel movements, can contribute to the development of hiatus hernia.
3. Genetic Predisposition: Certain inherited factors may predispose individuals to develop hiatus hernia.
4. Smoking: Cigarette smoking can weaken the LES and increase the risk of hiatus hernia and associated symptoms.

Symptoms
The symptoms of hiatus hernia can vary depending on the type and size of the hernia and the extent of acid reflux or complications. Common symptoms may include:

1. Heartburn: A burning sensation in the chest, often occurring after meals or when lying down, due to stomach acid refluxing into the oesophagus.
2. Regurgitation: Sour or bitter-tasting fluid or food that rises from the stomach into the throat or mouth.
3. Difficulty Swallowing: Dysphagia, or difficulty swallowing, may occur if the hernia compresses the oesophagus or causes narrowing (stricture) of the esophageal opening.
4. Chest Pain: Chest pain or discomfort, particularly when lying down or bending over, may occur due to acid reflux or irritation of the oesophagus. Hiatus hernias also associated with abnormal heart rhythms (arrhythmias).
5. Respiratory Symptoms: In severe cases, hiatus hernia may cause respiratory symptoms such as chronic cough, wheezing, or shortness of breath, especially when lying flat.

Occasionally, even large hiatus hernias are discovered incidentally on imaging performed for other reasons. In this case, surgery may be offered after considering the patient’s underlying health, the size of the hernia and any symptoms which could be ascribed to the hernia.

Diagnosis
Diagnosing hiatus hernia typically involves a combination of medical history assessment, physical examination, and diagnostic tests. Common diagnostic tests may include:

1. Upper Endoscopy: A procedure in which a thin, flexible tube with a camera (endoscope) is passed through the mouth and into the oesophagus and stomach to visualize the area and identify the presence of a hiatus hernia.
2. Imaging: A CT scan can delineate the anatomy of a complex hernia and allow for operative planning.
3. Esophageal Manometry: A procedure that measures the pressure and function of the muscles in the oesophagus to assess for abnormalities in swallowing and reflux.

Treatment
Treatment for hiatus hernia aims to alleviate symptoms, reduce acid reflux, and prevent complications. Treatment options may include:

1. Lifestyle Modifications: Making changes to diet and lifestyle habits, such as avoiding large meals, eating slowly, avoiding trigger foods, maintaining a healthy weight, and avoiding lying down or bending over after meals, can help reduce symptoms of acid reflux associated with hiatus hernia.
2. Medications: Over-the-counter or prescription medications, such as antacids, H2-receptor antagonists, or proton pump inhibitors (PPIs), may be used to reduce stomach acid production, neutralize acid, and alleviate symptoms of acid reflux.
3. Surgery: In severe cases of hiatus hernia that do not respond to conservative treatments or are associated with complications such as severe reflux or risk of strangulation of the herniated stomach, surgical intervention may be necessary to repair the hernia and reinforce the lower esophageal sphincter. The surgery involves bringing the stomach (and other organs if necessary) down back into the abdomen, tightening the hiatus with stitches and reinforcing the repair with a fundoplication.