What Is the Pylorus and How Does It Relate to Reflux?

When it comes to gastro-oesophageal reflux disease (GORD/GERD), many people think about ‘acid’ and stomach contents rising up into the oesophagus. But the story doesn’t begin and end at the top of the stomach. Another part of the digestive system – the pylorus – can play an important role in how reflux happens, especially in people with certain motility disorders.

What even is the pylorus?

The pylorus is a muscular valve at the bottom of the stomach. It controls the flow of partially digested food (called chyme) from the stomach into the small intestine. Think of it as the stomach’s exit door.

At the other end, at the top of the stomach, is the lower oesophageal sphincter (LOS). This valve helps prevent stomach contents from moving back up into the oesophagus. So, the stomach is bookended by these two valves: the LOS at the top and the pylorus at the bottom.

What does the pylorus have to do with reflux?

When the pylorus isn’t working properly, for example in a condition called gastroparesis, food and stomach contents can hang around in the stomach for too long. This delayed emptying can cause abdominal bloating, pressure and distension, increasing the likelihood of reflux. In other words, if the stomach can’t empty effectively through the bottom, contents are more likely to escape upward past the LOS.

A recent study using a computer-based model of the stomach helped shed light on this process. It found that when the pylorus is dysfunctional or if stomach wall movements are impaired, duodenogastric reflux can occur – where contents from the small intestine flow backward into the stomach, sometimes even reaching the oesophagus. This adds another dimension to reflux beyond acid, such as bile reflux, which may be harder to treat.

Could the pylorus also be too loose?

While much of the focus is on delayed emptying, it’s also possible for the pylorus to become incompetent, allowing contents from the small intestine to reflux back into the stomach. This is known as duodenogastric reflux, and it can introduce bile into the stomach: potentially worsening symptoms for people with bile-sensitive GORD.

What role does bile play in reflux?

Unlike stomach acid, bile is alkaline and not affected by acid-suppressing medications like PPIs. When bile refluxes up through the pylorus and into the stomach, and potentially into the oesophagus, it can cause inflammation and damage, particularly in people who don’t respond to standard reflux treatments. Recognising bile as a contributor can help guide different diagnostic and treatment approaches.

What happens in gastroparesis?

Gastroparesis is a condition where the stomach muscles don’t contract properly, which slows or prevents emptying into the small intestine. People with gastroparesis often experience symptoms like:

• Bloating or fullness after meals
• Nausea or vomiting
• Early satiety (feeling full quickly)
• Reflux or regurgitation

In some cases, gastroparesis overlaps with GORD. That’s why understanding the role of the pylorus is so important in complex reflux cases.

Are there treatments that target the pylorus?

Yes. In people with medication- and diet-resistant gastroparesis, procedures to improve drainage through the pylorus can help relieve pressure and symptoms:

• Pyloroplasty: a surgical widening of the pyloric valve
• G-POEM (gastric peroral endoscopic myotomy): an endoscopic procedure that cuts the pyloric muscle to help the stomach empty more effectively

Doctors don’t use these as first-line treatments for reflux, but they may recommend them when delayed gastric emptying contributes to symptoms.”

Does surgery near the pylorus affect reflux?

A large Swedish study published in Surgery for Obesity and Related Diseases (2025) found that the distance from the pylorus to the resection edge during sleeve gastrectomy had a measurable impact on reflux outcomes. A greater distance (i.e. leaving more of the stomach intact near the pylorus) was linked to a higher risk of post-surgical reflux, suggesting that how the stomach empties plays a role in long-term reflux control.

What else is good to know?

The pylorus may not get much attention in everyday reflux discussions, but it plays a key role in regulating pressure and flow within the digestive tract. When this muscle isn’t working well, it can add to the burden on the lower oesophageal sphincter, making reflux more likely.

Understanding the full picture of how your stomach is functioning, and not just what’s happening at the top, can make a big difference in getting to the root of reflux symptoms.

Always speak to a healthcare professional if you’re struggling with reflux, bloating or digestive symptoms that don’t respond to standard treatment.