In this review, Lacy et al have discussed the etiology, diagnosis and management of chronic abdominal distension and bloating, which are amongst the most commonly reported gastrointestinal symptoms. However, because of their nonspecific nature, evaluating a patient with symptoms of bloating and distension becomes a challenge. While abdominal bloating is subjective and described as feeling of trapped gas or sensation of fullness or pressure in the abdomen, abdominal distension is an increase in abdominal girth and is an objective measurement. Although recognised as distinct entities, the two often occur together. These symptoms may occasionally overlap with other functional GI disorders such as functional dyspepsia, irritable bowel syndrome, and functional constipation.

Many patients with abdominal bloating and distension may have an underlying organic cause such as small intestinal bacterial overgrowth (SIBO), carbohydrate intolerance, Celiac disease, gastrointestinal or gynecologic malignancy, hypothyroidism, gastroparesis. In some persons, the symptoms may be due to disorders of gut-brain interaction such as irritable bowel syndrome (IBS), chronic idiopathic constipation, delayed intestinal transit, disordered visceral sensation, or may be functional.

Diagnostic evaluation begins with a carefully elicited history and physical examination, which may provide clues to the etiology and the relevant investigations. The contribution of diet, medications and behavioral factors should also be reviewed. The diagnostic tests include breath tests to measure carbohydrate intolerance (lactose and fructose) and serology to measure tissue transglutaminase IgA (tTG-IgA) to rule out Celiac disease. Endoscopic evaluation (UGIE) is indicated in patients with alarm symptoms (recurrent nausea and vomiting, unexplained anemia, hematemesis, weight loss >10% of body weight, a family history of gastroesophageal malignancy) or those in whom gastric outlet obstruction, gastroparesis or functional dyspepsia is suspected. Imaging modalities like an abdominal x-ray or CT abdomen, CT or MRI enterography are also useful diagnostic aids. 

Different therapeutic options have been described, which include dietary changes (avoiding use of artificial sweeteners, low FODMAP diet), probiotics to modify the gut microbiome, antibiotics, prokinetics, antispasmodics and neuromodulators. Biofeedback therapy has been shown to improve abdominal distension in a small study. The authors also suggest a role for complementary and alternative medicine, though indirect, citing a placebo-controlled study of peppermint oil in patients with IBS with diarrhea, which led to significant improvement in symptoms of bloating or distension. Treatment involves the correct etiological diagnosis, severity assessment and educating and counselling patients. Besides efficacy and safety, the selection of a therapeutic strategy should also involve discussion about its risks and benefits as well as cost of treatment.

Lacy BE, et al.  Clin Gastroenterol Hepatol. 2021 Feb; 19(2):219-231.e1.