A paraesophageal hernia develops when part of the stomach pushes up through the diaphragm alongside the esophagus, usually because the connective tissue anchoring the stomach in place has weakened or torn. Unlike the more common sliding hiatal hernia (where the junction between the esophagus and stomach slides upward), a paraesophageal hernia involves the stomach bulging through a defect in the tissue next to the esophagus while that junction may stay in its normal position. The causes are rarely a single factor. Instead, a combination of tissue degeneration, physical stress on the diaphragm, and sometimes congenital anatomy creates the conditions for herniation.
The Ligament That Holds Everything in Place
The key structure involved is the phrenoesophageal ligament, a sheath of connective tissue on the underside of the diaphragm. This ligament attaches to the lower esophagus and the top of the stomach, anchoring them below the diaphragm’s opening (the hiatus). It also helps maintain the acute angle where the esophagus meets the stomach, which acts as a natural valve against acid reflux.
When this ligament weakens, stretches, or develops a localized defect, the stomach can migrate upward through the hiatus. In a true paraesophageal hernia (sometimes called Type II), a specific defect forms in the ligament, typically on the left rear side. This creates a gap that allows the stomach’s upper portion, the fundus, to slide up beside the esophagus into the chest cavity. In the most common form of paraesophageal hernia (Type III), the ligament progressively stretches over time, the hiatal opening widens, and a larger portion of the stomach herniates upward along with the esophageal junction itself. In the most advanced cases (Type IV), other abdominal organs like the colon or spleen can follow the stomach through the enlarged opening.
Age-Related Tissue Breakdown
The single biggest contributor to paraesophageal hernia formation is the gradual deterioration of connective tissue with age. Over time, the phrenoesophageal ligament loses collagen fibers, which reduces its tensile strength and its ability to snap back into shape. Research has found that the balance between different types of collagen in the ligament shifts in people with hiatal hernias: there’s an increased ratio of certain collagen types and an overall decrease in the structural proteins that keep the tissue strong. This weakened ligament can no longer resist the upward pressure from the abdomen, allowing the stomach to migrate into the chest.
The diaphragm muscle itself also loses tone with age. The muscle fibers surrounding the hiatus normally pinch the esophagus snugly during breathing and swallowing. As these fibers weaken, the opening gradually widens. This is why paraesophageal hernias are far more common in people over 60 than in younger adults.
Pressure From Below
Anything that chronically increases pressure inside the abdomen pushes the stomach upward against the diaphragm, stressing the already vulnerable ligament. The most well-established pressure sources include:
- Obesity: Excess abdominal fat creates sustained upward force on the diaphragm. This is one of the strongest modifiable risk factors.
- Chronic coughing: Conditions like COPD generate repeated spikes of intra-abdominal pressure with every cough.
- Chronic constipation: Frequent straining during bowel movements transmits pressure directly to the diaphragm.
- Pregnancy: The growing uterus pushes abdominal contents upward, though pregnancy-related hernias often improve after delivery.
- Heavy lifting: Repeated exertion, whether occupational or recreational, raises abdominal pressure acutely and, over years, can contribute to ligament fatigue.
These factors don’t cause a hernia overnight. They work over months or years, gradually stretching the phrenoesophageal ligament and widening the hiatal opening until the stomach can slip through.
Congenital and Structural Factors
Some people are born with a wider-than-normal hiatal opening or with connective tissue that is inherently less resilient. These congenital differences help explain why paraesophageal hernias occasionally appear in younger people without obvious risk factors. While true congenital diaphragmatic hernias (where the diaphragm fails to form properly during fetal development) are a distinct condition, subtle variations in hiatal anatomy can set the stage for a paraesophageal hernia to develop later in life, especially if combined with any of the pressure factors above.
Prior Abdominal or Esophageal Surgery
Paraesophageal hernias can develop as a complication of previous surgery near the hiatus. In a review of 720 patients who underwent laparoscopic surgery for acid reflux (Nissen fundoplication), seven developed a paraesophageal hernia afterward that required a second operation. The risk is small, but surgery in this area disrupts the normal tissue attachments around the hiatus. If the repair doesn’t hold or the hiatus isn’t closed securely, the stomach can herniate through the weakened area. Early difficulty swallowing after such surgery is a warning sign of this complication.
Why the Type Matters
Not all paraesophageal hernias carry the same risk. Small hernias may cause no symptoms and are sometimes discovered incidentally on imaging done for other reasons. Larger hernias, particularly Type III and IV, can cause chest pain, difficulty swallowing, feeling full quickly after eating, or shortness of breath from the stomach compressing the lungs.
The most serious concern with paraesophageal hernias is that the herniated stomach can twist on itself (gastric volvulus) or become trapped (incarcerated), cutting off blood supply. This is a surgical emergency. The estimated incidence is about 1.2% per patient per year, so it’s uncommon but not negligible, especially in people with large hernias. Stomach tissue that loses blood supply can perforate, which is the primary cause of death from this condition.
Reducing Your Risk
Because the causes are cumulative, reducing the controllable factors makes a real difference. Maintaining a healthy weight removes the most consistent source of chronic abdominal pressure. Managing chronic coughs (whether from COPD, asthma, or smoking) and treating constipation both reduce repeated strain on the diaphragm. Avoiding heavy lifting or using proper technique when you must lift helps as well. Good posture, while it sounds minor, reduces sustained compression on the abdomen.
None of these measures can reverse age-related tissue changes that have already occurred, but they can slow progression and reduce the chance that a small, asymptomatic hernia becomes a large, symptomatic one.