A hiatal hernia happens when part of your stomach pushes up through a small opening in your diaphragm called the hiatus. Normally, the hiatus is just wide enough for your esophagus (your food pipe) to pass through on its way to your stomach. When the tissues around that opening weaken or stretch, the upper portion of your stomach can slide or bulge upward into your chest cavity.
Understanding how this happens starts with the anatomy. Your diaphragm is a dome-shaped muscle that separates your chest from your abdomen. Where your esophagus passes through it, a ring of elastic tissue holds everything snug. When that ring loosens, the door is open for a hernia to form.
What Weakens the Diaphragm Opening
The tissue holding your esophagus in place at the diaphragm is called the phrenoesophageal membrane. Over time, this membrane loses its elastic fibers through the repetitive stress of swallowing, breathing, and everyday movement. This gradual wear and tear is the single biggest reason hiatal hernias are so common in older adults. The opening slowly widens, and the stomach gains room to migrate upward.
Anything that increases pressure inside your abdomen can accelerate the process or trigger the hernia outright. Common culprits include:
- Chronic coughing or sneezing from conditions like asthma, COPD, or allergies
- Straining during bowel movements over months or years, often from chronic constipation
- Repeated heavy lifting or intense physical exertion that bears down on the abdomen
- Pregnancy, which pushes abdominal organs upward as the uterus expands
- Persistent vomiting or severe retching
Think of it like squeezing a tube of toothpaste with the cap loosened. The pressure from below pushes contents toward whatever opening gives way first. In this case, that opening is the hiatus.
Why Body Weight Matters
Carrying extra weight around your midsection is one of the strongest independent risk factors. A study in the American Journal of Gastroenterology found that the probability of having a hiatal hernia increased at every level of BMI, with each step from normal weight to mildly overweight to obese raising the risk significantly. Excess abdominal fat creates constant upward pressure on the stomach, stressing the hiatal opening day and night. Losing weight can reduce that pressure, though it won’t reverse a hernia that has already formed.
The Role of Age and Genetics
Most hiatal hernias develop gradually over decades. The elastic tissue around the hiatus weakens with age, which is why these hernias are far more common after 50. Some people are also born with a naturally wider hiatus, giving them less of a buffer before a hernia develops. Congenital diaphragmatic abnormalities, where the diaphragm doesn’t fully form during fetal development, are a separate and much rarer condition typically diagnosed in infancy. But a mildly larger-than-average hiatus at birth can set the stage for a hernia later in life when age and pressure do their work.
Types of Hiatal Hernias
Not all hiatal hernias look the same. They’re classified into four types based on what moves through the opening and how.
Type 1 (sliding) accounts for about 95% of all hiatal hernias. The junction where your esophagus meets your stomach slides upward through the hiatus, then often slides back down. It moves. Many people with a small sliding hernia never know they have one.
Type 2 (paraesophageal or “rolling”) is different. Here, the esophageal junction stays in place, but a portion of the stomach pushes up alongside the esophagus and forms a bulge next to it. This type is less common but can be more concerning because the stomach can become trapped or twisted.
Type 3 combines both patterns. The esophageal junction slides upward and a separate part of the stomach also bulges through the hiatus beside it.
Type 4 is rare and involves a hiatus wide enough for another organ, such as part of the intestine, the pancreas, or the spleen, to herniate alongside the stomach. This type carries the highest risk of complications.
How a Hernia Causes Symptoms
A hiatal hernia doesn’t always cause problems. Many small sliding hernias produce no symptoms at all and are discovered incidentally during imaging or endoscopy for something else. When symptoms do appear, the most common one is acid reflux, and the mechanism is straightforward.
Your lower esophageal sphincter is a ring of muscle at the bottom of your esophagus that acts as a one-way valve, keeping stomach acid where it belongs. When a hiatal hernia pulls the stomach upward, it changes the geometry of this valve. Research shows that a hiatal hernia reduces the sphincter’s resting pressure and shortens the portion of it that sits within the abdomen, where abdominal pressure normally helps keep it shut. The altered angle makes it easier for stomach acid to be pulled back up into the esophagus, especially when lying down or after meals.
Larger paraesophageal hernias (types 2 through 4) can cause a different set of problems. Because part of the stomach sits up in the chest cavity, you might feel full quickly, have difficulty swallowing, or experience chest pressure. Some people develop shortness of breath or exercise intolerance because the herniated stomach takes up space near the heart and lungs.
How It’s Diagnosed
Hiatal hernias are typically found through one of three methods. A barium swallow involves drinking a chalky liquid and then taking X-rays as it travels down your esophagus, which outlines the hernia clearly. An upper endoscopy, where a thin camera is passed down your throat, lets a doctor see the hernia directly. A third option, pressure testing of the esophagus, can detect a hernia by measuring the gap between the sphincter and the diaphragm. A separation greater than 2 centimeters between those two landmarks is the standard threshold for diagnosis.
Many hiatal hernias are found accidentally during tests ordered for other reasons, like chest pain or chronic cough. If you’ve been told you have one, it doesn’t necessarily mean it needs treatment.
When Treatment Is Needed
Management depends on the type of hernia, its size, and whether it’s causing problems. For a small sliding hernia with mild reflux, the approach is usually lifestyle changes: eating smaller meals, not lying down right after eating, elevating the head of your bed, and avoiding foods that trigger reflux. Acid-reducing medications can control symptoms effectively for most people in this category.
Surgery becomes part of the conversation when symptoms don’t respond to these measures, when the hernia is large, or when it’s a paraesophageal type that carries a risk of the stomach becoming trapped or losing its blood supply. The most common surgical repair is done laparoscopically, through small incisions. The surgeon pulls the stomach back into the abdomen, narrows the hiatus, and often wraps the top of the stomach around the lower esophagus to reinforce the valve.
For paraesophageal hernias that aren’t causing obvious digestive symptoms, the decision is trickier. Some patients with these hernias experience subtle problems like shortness of breath or exercise intolerance that they don’t initially connect to their hernia. Guidelines from the Society of American Gastrointestinal and Endoscopic Surgeons note that these patients may benefit from repair if the symptoms can reasonably be attributed to the hernia rather than another condition. For truly asymptomatic large hernias, surgical repair may still be offered on a case-by-case basis, though the evidence supporting that approach is limited.