What Is Abdominal Distension?

tape measure around belly
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Distension is defined as something that is enlarged or stretched beyond its normal state, typically from within. Abdominal distension is a sense of increased abdominal pressure that involves an actual measurable change in the circumference of a person's abdomen.

Distension can be measured through the use of a tape measure. Distension over the course of a day can be measured more reliably by a device known as 'ambulatory abdominal inductance plethysmography' (AIP).

Such a device would most likely only be used during the course of a research study.

How Is Distension Different than Bloating?

When a person feels bloated, they experience a sense of increased pressure in their abdomen, but without any measurable change. With distension, there is an actual widening to the size and circumference of the abdomen. Many people, including doctors, will often use the two terms interchangebly.

Although the causes of both bloating and distension have not yet been well-identified, there are some research indications that different (but related) mechanisms may be underlying each of the two problems.

Distension and Digestive Disorders

Bloating and distension are symptoms that are most characteristic of a functional gastrointestinal disorder (FGD), such as irritable bowel syndrome (IBS).

How many people who have IBS experience distension alongside bloating? Estimates range from 50 to 75%.

These patients are more likely to report it as a highly bothersome symptom. Distension is more likely to be reported by patients who have constipation predominant irritable bowel syndrome (IBS-C) as opposed to diarrhea predominant IBS (IBS-D). Studies have shown that a slowing of transit time of fecal matter through the gut is related to the experience of distension.

Typically, patients will report that distension is more likely to occur after meals and will worsen as the day goes on, with a reduction in the symptom overnight. Distension that increases as the day wears on is most likely due to an FGD. Distension that occurs 24/7 may be indicative a more serious health problem.

Causes of Distension

Although is seems like common sense to say that distension is related to excessive amounts of intestinal gas, this theory has not been fully supported by research. Rather, it may be that it is the way that the digestive systems of people who have IBS handles the gas that is the problem.

Another theory suggests that distension is related to a dysfunctional reflex of the muscles of the abdomen, triggered by the act of eating a meal. More research is needed to validate or discount this theory.

Treatment of Abdominal Distension

There are a variety of things that can cause of abdominal distension (as well as bloating!). Therefore there are no treatments identified that specifically target the symptom of distension.

Instead, treatment focus on dealing with the symptoms of the overall digestive disorder. Sources:

Agrawal, A. & Whorwell, P. "Review Article: Abdominal Bloating and Distension in Functional Gastrointestinal Disorders -- Epidemiology and Exploration of Possible Mechanisms" Alimentary Pharmacology & Therapeutics 2008 27:2-10.

Lea, R. & Whorwell, P. "Expert Commentary – Bloating, Distension, and the Irritable Bowel Syndrome" MedGenMed 2005 7:18.

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