Dr Lacy discusses how to discern between bloating and distension, identifies the key contributors to these conditions, and goes through the treatment options he presented at the ACG Scientific Meeting. 

Brian Lacy, MD, PhD, is a professor of medicine at Mayo Clinic-Florida in Jacksonville, Florida.

Bloating and Distension: Evaluation and Targeted Management

• Bothersome gas and bloating affect approximately 14% of US adults, according to a survey of nearly 90,000 adults. Bloating describes perceived gassiness or fullness; distension is the physical manifestation.
• History should assess 5 common contributors: diet, constipation, intestinal overgrowth, visceral hypersensitivity, and abdominophrenic dyssynergia. Review lactose, fructose, fermentable carbohydrates, and sugar alcohols; extensive diagnostic testing is rarely required.
• Treatment targets the contributor: dietary interventions, neuromodulators for visceral hypersensitivity, antibiotics for bacterial overgrowth identified through breath testing, and diaphragmatic breathing for abdominophrenic dyssynergia. Head-to-head antibiotic comparisons are unavailable.

Welcome. I'm Brian Lacy, professor of medicine at the Mayo Clinic in Jacksonville, Florida. I'm here in Nashville, Tennessee at the ACG annual meeting. One of the topics we discussed at the meeting this year was that of bloating and distension. And this is a common topic that gastroenterologists and primary care providers face all the time.

Let me spend a few minutes kind of giving you my approach for the patient with bloating and distension. And this is really important because these symptoms of bloating, and bloating is a symptom of gassiness or trapped gas or ‘I feel full’ is a little bit different than the symptom of distension. Distension is the physical manifestation. Patients will say, "Gosh, I feel like there's a beach ball and I look 3 or 6 or 8 months pregnant." This is a problem that crosses medical borders, meaning gynecologists see this and primary care providers see this, and certainly gastroenterologists see this as well.

And this is quite common. As a matter of fact, a recent survey study of nearly 90,000 US adults identified that about 14% of US adults have symptoms of gas and bloating that are bothersome. So whether you want to deal with this problem or not, we see these patients and it's important to understand a good pathway forward.

So with that in mind, the first step is taking that great history, trying to identify why patients have symptoms of gas and bloating. And there's a long laundry list, but the way I explain it to my patients is that there are really 5 major common offenders to have symptoms of gas and bloating. And the first is that of diet, and I'll go through some of the worst dietary offenders in a second. The next are symptoms related to constipation. And the way I explain it to my patients is if it's difficult to evacuate stool, it's frequently difficult to evacuate gas as well.

A third major reason is that of intestinal overgrowth. And you're going to see a change in the terminology in the next year where we talk about intestinal overgrowth with 3 specific subtypes: that of SIBO, small intestine bacterial overgrowth, or intestinal methanogen overgrowth, IMO, or intestinal sulfide overgrowth. So we have to think about this umbrella term and now 3 specific subgroups.

Then there's a large category of visceral hypersensitivity. So we know that most patients with symptoms of gas and bloating don't produce more gas than others. They just sense it differently. And this is why gas and bloating is so commonly reported in patients with IBS or functional dyspepsia or chronic constipation, those disorders of gut-brain interaction. Their gut is sensitive and they're sensitive to normal amounts of gas.

Lastly, there's a category of what we call abdominophrenic dyssynergia, meaning that when patients ingest a meal, they very rapidly have symptoms of distension, that physical manifestation. And this is a little bit of a wiring problem. And let me explain that, meaning that the abdominal cavity has a certain amount of size. Normally when we have gas in the GI tract, we sense it through mechanoreceptors. And then what happens is the diaphragm ascends, it makes your abdominal cavity larger. And without us thinking about it, our abdominal wall muscles, external obliques, rectus sheath, contract to keep our abdomens reasonably flat. However, some people with this abdominophrenic dyssynergia, their wiring is completely opposite. And when they sense that gas without thinking about it, their diaphragm descends. Now that abdominal cavity is smaller and their abdominal wall muscles abnormally relax and now they quickly have that protuberance or distension.

So those are the 5 major categories. Again, putting on your detective hat, let's go back to the first—diet. What are the worst offenders? So lactose intolerance, don't forget that 35% of adult Americans are lactose intolerant. And that's even higher in some groups such as Asians or Blacks, African Americans, as high as 80 or 85%. Number 2, fructose intolerance, and that frequently coexists with lactose intolerance. There's a lot of buzz and information about sucrose intolerance. That's actually not as common. Congenital sucrase deficiency is one in 20,000 patients, but it may be a little bit higher, 2% in patients with IBS and diarrhea. Let's think about other foods. And clearly we're all educated now. We're knowledgeable about FODMAPs, fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. These are the foods that cause gas and bloating. So think about fructans, onions and peppers and asparagus. Think about complex carbohydrates, which can ferment. So legumes—black beans, red beans, garbanzos. Think about cruciferous vegetables. Think about sugar-free candies, gums, and mints, and anything that ends in OL. So erythritol, mannitol, lactitol, all cause gas and bloating. So being a good detective here, going through your patient's diet.

So then in terms of treatment, the way I like to think about it is this diet, and we just discussed kind of the worst dietary offenders, is this a disorder of where the gut is too sensitive? And so for many of these patients with bothersome symptoms, we may recommend neuromodulators such as a low-dose tricyclic or maybe something like gabapentin or pregabalin to help with visceral hypersensitivity. If bacterial overgrowth is a cause—and that could be identified with breath testing, whether a lactulose breath test or a glucose breath test—then you may want to consider antibiotics, recognizing we do not have head-to-head comparison studies comparing one antibiotic to another. And so this is really up to the clinician's choice.

Those patients with abdominophrenic dyssynergia, and classically that's the patient who reports significant bloating shortly after eating a meal or even during the meal, those patients are best treated with a diaphragmatic breathing. So my patients with abdominal bloating distension, I think you can either be kind of nervous about approaching these patients or cautious or fearful that you're going to get in this long discussion. I would argue, have fun with the discussion. This is a nonspecific symptom. It rarely represents anything bad or dangerous. Extensive diagnostic testing is rarely required.

Take that good history, focus on dietary factors, think about visceral hypersensitivity, think about how common it is with disorders of gut-brain interaction, and then think about those dietary interventions, consider the treatment for bacterial overgrowth, use neuromodulators and consider diaphragmatic breathing. Hopefully this helps you with your practice. Here in Nashville, Tennessee, I'm Brian Lacy, professor of medicine at the Mayo Clinic in Jacksonville, Florida, and good luck with your patients.