Bloating and distension are not the same thing
The distinction is worth making, because it guides the diagnosis. Bloating is the subjective sensation of pressure or fullness. Distension is the real, visible increase in abdominal girth: the belly that grows through the day and has you undoing your waistband by the evening.
Many patients have both, but they do not always go together, and when distension is objective and striking there are specific things worth excluding before assuming anything.
The causes worth looking for
Contrary to what is usually said, it is almost never "too much gas". The amount of gas in the abdomen of someone with distension is usually normal; what goes wrong is how it is distributed, how it is transported and how the gut perceives it.
- Irritable bowel syndrome, by far the commonest cause
- Constipation, often not recognised as such by the patient
- Coeliac disease and lactose or fructose intolerance
- Small intestinal bacterial overgrowth, real but heavily overdiagnosed
- Abdominophrenic dyssynergia, an uncoordinated reflex of the diaphragm and abdominal wall that explains many striking cases and has specific treatment
- Disorders of gastric emptying
- Gynaecological or liver causes and ascites, uncommon but essential to exclude
When it needs investigating promptly
Distension appearing for the first time after the age of 50, accompanied by weight loss, bleeding, vomiting or difficulty swallowing, or persistent and progressive rather than fluctuating through the day. In those cases the priority is different.
On SIBO and food intolerance tests
It is worth being blunt here, because this is where patients' desperation is most exploited. Bacterial overgrowth exists and is treatable, but the breath test has a notable false positive rate and should not be used as blanket screening for everyone with a bloated abdomen.
IgG food antibody tests, hair sample intolerance tests and commercial microbiome analyses have no validity for clinical decisions. They generate lists of forbidden foods, ever narrower diets and a new problem on top of the original one.
My rule
I request a test when its result will change what we do, and not before. If a test will not alter treatment, all it produces is an invoice and anxiety.
What can be done
- Identify and treat the specific cause, which almost always exists
- Correct underlying constipation, which improves distension faster than anything else
- Phased dietary intervention, with reintroduction rather than indefinite restriction
- Targeted antibiotic treatment when overgrowth is genuinely confirmed
- Retraining of diaphragmatic breathing and posture in abdominophrenic dyssynergia, with very good results and barely known outside specialist practice
- Drugs for visceral hypersensitivity when perception is the main component
Why this consultation matters to me
Because this is where patients arrive most worn down. They usually come after years of increasingly restrictive diets, expensive tests that led nowhere and one supplement after another, feeling that nobody has taken seriously something that shapes their daily life.
There is almost always an identifiable explanation and a treatment that makes sense. And it almost always involves doing less, not more.