Expert Advice on Bloating

A recent article (AK Kamboj, AS Oxentenko. Clin Gastroenterol Hepatol 2018; 16; 1030-33) provides some useful guidance on bloating.

They describe bloating as an acronym:

  • Bowel disturbance (constipation, SIBO, celiac, IBD)
  • Liquid (ascites)
  • Obstruction
  • Adiposity
  • Thoracic (overexpansion, diaphragm contraction)
  • Increased sensitivity (functional bloating, IBS, dyspepsia)
  • Neuromuscular (gastroparesis, impaired accommodation, medications)
  • Gas (aerophagia, dietary sources, post-Nissen)

The diagnostic approach they recommend:

  • If bloating with diarrhea, evaluate diet, SIBO, celiac, IBD, IBS-D, and medications
  • If bloating with constipation, evaluate for constipation, pelvic floor dysfunction, IBS-C, and medications
  • If bloating and suspected mechanical disturbance, evaluate for gastric outlet obstruction/small bowel obstruction
  • If bloating without bowel disturbance, consider aerophagia, gastroparesis, and functional dyspepsia


  • Treat any underlying disorder
  • For mild symptoms, reassurance may be sufficient
  • Dietary modifications to avoid food triggers & reduce fermentable food products
  • Treating constipation when present
  • A large number of other treatments can be considered as well including antispasmotics, agents to help with visceral hyperalgesia, cognitive behavioral therapy

My take: I like BLOATING acronym, though the 5 Fs I learned a long time ago is a little easier for me to remember — which include flatus (gas), feces (constipation), fluid, fat, and fetus/masses. Flatus can be caused by swallowing air (aerophagia), malabsorption (celiac, lactose intolerance, parasites), muscular discoordination (abdominal phrenic dyssynergia), and motility problems.”

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Sunshine Meadows, Banff National Park

Understanding Functional Abdominal Distention

A recent study (Barba E, et al. Gastroenterol 2015; 148: 732-9) provides insight into why some patients develop functional abdominal distention.

In this prospective study of 45 patients (42 women), the researchers performed numerous tests to determine the reasons for abdominal distention.  Most patients had CT scan (n=39), and electromyography (EMG) of the abominothoracic wall (n=32) both at baseline and during distention. In addition, 15 patients underwent EMG-guided biofeedback.


  • Abdominal distention was associated with diaphragm contraction (~19% increase from baseline) and intercostal contraction (~14% increase from baseline).
  • There was an increase in thoracic antero-posterior diameter compared with basal values with increase in anterior abdominal wall protrusion.
  • Biofeedback treatment was effective in reversing these changes.  This indicates that the distention is under voluntary control.

The authors use the term for the changes that cause the abdominal distention as “abdominal accommodation.”  They note that “in healthy subjects, an increase in intra-abdominal contents induces relaxation and ascent of the diaphragm, which permits cephalic expansion of the abdominal cavity with minor protrusion of the anterior wall.” In this study, the distention was determined in real-life settings to be due to “a paradoxical contraction of the diaphragm, that pushed abdominal contents downward, and relaxation of the anterior abdominal wall.”

Bottomline: These experiments provide a ‘proof-of-concept’ regarding the mechanisms of abdominal distention, though these experiments are not practical for most patients with these symptoms.

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Abdominal distention – a medical mystery?

A recent ‘think like a doctor’ case in the NY Times involved a patient sent to a pediatric gastroenterologist for abdominal distention.  It’s worth a read (thanks to Ben Enav for sharing this reference).

With regard to bloating and distention, the ‘smartphrase’ that I use to discuss this issue with parents is based on the “5 Fs” that I learned during fellowship.  I decided to modify the phrase a little bit based on the above case:

” I reviewed the issue of bloating/distention with family. Typically, distention or bloating can be caused by “5 Fs” which include flatus (gas), feces (constipation), fluid, fat, and fetus/masses. Flatus can be caused by swallowing air (aerophagia), malabsorption (celiac, lactose intolerance, parasites), muscular discoordination (abdominal phrenic dyssynergia), and motility problems.”

Are there other etiologies that you discuss with your patients?

Does buspirone help functional dyspepsia?

A recent randomized, double-blind, placebo-controlled crossover functional dyspepsia (FD) trial showed that 4 weeks of treatment with buspirone (10 mg TID) improved overall symptom severity, including early satiety and bloating (Clin Gastroenterol Hepatol 2012; 10: 1239-45).

This study enrolled 17 patients (13 women) with a mean age of 38.5 years.  There were two 2-week treatment periods and a 2-week washout in between.  Patients filled out a dyspepsia symptom score before treatment and at the conclusion.  In addition, patients underwent gastric emptying by using breath tests and barostat measurement.

Overall symptom score was improved with buspirone compared to placebo: 7.5 ± 1.3 vs. 11.5 ± 1.2.  Symptoms of postprandial fullness, early satiety, and abdominal bloating all improved significantly.

Buspirone treatment increased gastric accommodation compared with placebo: 229 ± 28 vs. 141 ± 32 mL respectively.  Overall, gastric emptying was not affected by buspirone treatment; however, delayed emptying of liquids was evident (half-life = 64 vs. 119 minutes respectively).

The effect of buspirone on FD appears to be primarily related to improvement in gastric accommodation.  Impaired accommodation has been identified in about 40% of FD patients.  Buspirone which is a 5-HT1A receptor agonist acts on cholinergic nerve endings and leads to relaxation of the proximal stomach.

Buspirone also is used for the treatment of anxiety.  In the present study, baseline anxiety scores were not correlated to symptom improvement but these scores were not followed at the end of treatment.

In this small study, buspirone was well tolerated and had similar adverse events as placebo.  In previous studies, it has been associated with light-headedness, dizziness, and nausea.

Given the small scale of the study, it would be premature to consider buspirone a proven treatment for FD; however, this study provides the framework for larger studies to determine more conclusively the role of buspirone for FD.

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