Abdominal bloating vs distension - what's the difference?

Bloating and distension are common symptoms in IBS, and the terms are often used interchangeably. But did you know that they are actually different? 

Bloating refers to the  sensation of abdominal (tummy) swelling, sometimes described as the feeling of an inflated balloon in the belly. By contrast, abdominal distention refers to an actual increase in measured abdominal size. Figure 1 highlights the difference between these symptoms.

The increase in abdominal size associated with abdominal distension can be measured using a technology called abdominal inductance plethysmography (AIP) (Figure 2). Studies using this technique have shown that abdominal size can increase by as much as 12 cm in some patients.¹

Figure 1 -Differences between bloating and distension. Source - https://www.iffgd.org 

Figure 2- Abdominal inductance plethysmography (AIP) being used to measure abdominal distension. Source: Agrawal A, et al. Review article: abdominal bloating and distension in functional gastrointestinal disorders--epidemiology and exploration of possible mechanisms. Aliment Pharmacol Ther 2008;27:2-10.

How common is bloating?

Over 90% of patients with IBS may be affected by bloating, and the condition is also common in the general population, affecting 10-30% of individuals. The symptom is unpleasant, with many patients rating bloating as their most bothersome symptom2, 3. People with IBS-C tend to be more prone to bloating than those with IBS-D or IBS-M, as are females compared to males. This female predominance is seen even when the menstrual cycle is controlled for, although some have argued that men simply describe their bloating differently (as hardness or tightening in the abdomen), so their symptoms may be less often recognised as bloating. 

Abdominal bloating and distension may occur together or separately

Abdominal bloating and distension may occur together, but as you can see from Figure 1, this is not always the case. For instance, studies in people reporting bloating show that only half also have abdominal distension. 

Common features of abdominal bloating and distension

Despite the differences between abdominal bloating and visible distension, they share some common features. For example, both:

• are highly bothersome to patients; 
  
• may worsen over the course of the day;
  
• may be exacerbated by meals; 
  
• often resolve overnight.

Why is the distinction between abdominal bloating and distension important? 

The main reason to distinguish between abdominal bloating and distension is that there may be different underlying causes for these symptoms, so different treatments may be needed. Your doctor should be able to tell you if your symptoms are consistent with bloating, distension.  

In next week’s blog post, we explore more about the causes and treatments for abdominal bloating and distension in IBS. 

References:

1. Houghton LA, Lea R, Agrawal A, et al. Relationship of abdominal bloating to distention in irritable bowel syndrome and effect of bowel habit. Gastroenterology 2006;131:1003-10.
   
2. Maxton DG, Morris JA, Whorwell PJ. Ranking of symptoms by patients with the irritable bowel syndrome. BMJ 1989;299:1138.
   
3. Lembo T, Naliboff B, Munakata J, et al. Symptoms and visceral perception in patients with pain-predominant irritable bowel syndrome. Am J Gastroenterol 1999;94:1320-6.