Bloating

What causes bloating?

Medical students have historically been taught that the causes of abdominal bloating are the F’s.

• Foetus (Pregnancy)
• Fat.
• Faeces (Constipation)
• Fluid (For instance caused by liver failure)
• Flatus (Gas)

This is not a comprehensive list of causes. Others include gallstone disease, ovarian tumours and pancreatic causes. However, in the context of reflux symptoms the following may be associated;

• Aerophagia. Air swallowing may cause distension and venting of the stomach with belching causing reflux symptoms.
• H. pylori. Some patients testing positive for h. pylori will experience bloating, belching and reflux symptoms.
• Gastroparesis. Some patients with slow emptying of the stomach may describe upper abdominal bloating after food.
• Small Intestinal Bacterial Overgrowth (SIBO). Fermentation within the gut causes distention, belching and associated reflux symptoms.
• Bloating after some anti-reflux procedures, particularly fundoplication is common.

How is bloating diagnosed?

The cause of abdominal bloating is diagnosed by a combination of a clinician listening to a patient’s “history”, physical examination including visualisation of the throat and then diagnostic tests. If there are any “alarm” symptoms suggesting malignancy may be responsible these tests should be performed urgently. Excluding a structural cause for bloating usually requires imaging tests such as ultrasound and CT-scanning and/or blood tests.

Functional tests include;

• SIBO/Intolerance Tests; breath tests are most commonly used to diagnose small intestinal bacterial overgrowth (SIBO) and malabsorption of sugars such as lactose or fructose. In the case of SIBO, following drinking a sugar solution the exhaled breath is tested over two hours to measure the production of hydrogen and methane gases by gut bacteria.
• Gastric Emptying Studies; These assess how quickly a substance passes from the stomach into the small bowel either directly using radio-isotopes (usually technetium-99m) or indirectly using breath tests. It can help diagnose gastroparesis or a blockage.
• Electrogastrogram; Delayed emptying can have many causes and measuring the electrical activity in the stomach can help distinguish them from each other. This can be done using electrodes placed on the skin and is painless and non-invasive.
• 24 hour catheter reflux monitoring. A small tube (catheter) is inserted through the nose to the bottom of the oesophagus and measures reflux events usually over 24 hours at the bottom as well as the top of the oesophagus. It will also include a pH sensor in the stomach to ensure normal acid production. The catheter is attached to a recorder about the size of a mobile phone and patients can record when they experience symptoms allowing correlation between the two. These are known as “symptom associations”. pH testing assesses acidic/non acidic reflux events. Modern testing includes impedance which offers the advantage that it also distinguishes between liquid, solid and gas reflux events. So for instance, impedance can identify aerophagia and belching which may be associated with reflux.

What are the treatments for bloating?

The treatment of bloating is tailored to the cause.

When SIBO is diagnosed, treatment will often abolish or improve symptoms. SIBO treatments include;

• Identify and remove precipitants
• If PPIs provide no benefit stop.
• Trigger food avoidance
• Low FODMAP diet
• Pro-biotics
• Anti-biotic eradication regimes
• Other diets. e.g. Elemental diet

Page reviewed by: Mr Nick Boyle BM MS FRCS 01/09/24