Adv Ther https://doi.org/10.1007/s12325-019-00924-7 REVIEW Bloating and Abdominal Distension: Clinical Approach and Management Amir Mari . Fadi Abu Backer . Mahmud Mahamid . Hana Amara . Dan Carter . Doron Boltin . Ram Dickman Received: February 5, 2019 Ó The Author(s) 2019 ABSTRACT complaint) or may overlap with other func- tional gastrointestinal disorders such as func- Functional abdominal bloating and distension tional constipation, irritable bowel syndrome, (FABD) are common gastrointestinal com- and functional dyspepsia. The pathophysiology plaints, encountered on a daily basis by gas- of FABD is not completely understood. Pro- troenterologists and healthcare providers. posed underlying mechanisms include visceral Functional abdominal bloating is a subjective hypersensitivity, behavioral induced abnormal sensation that is commonly associated with an abdominal wall-phrenic reflexes, the effect of objective abdominal distension. FABD may be poorly absorbed fermentable carbohydrates, diagnosed as a single entity (the sole or cardinal and microbiome alterations. Management includes behavioral therapy, dietary interven- Enhanced Digital Features To view enhanced digital tions, microbiome modulation, and medical features for this article go to https://doi.org/10.6084/ m9.figshare.7776143. therapy. This review presents the current knowledge on the pathophysiology, evaluation, and management of FABD. A. Mari Á F. Abu Backer Gastroenterology Institute, Hillel Yaffe Medical Center, Hadera, Israel A. Mari Á M. Mahamid Á H. Amara Keywords: Distension; Functional abdominal Gastroenterology Institute, Nazareth EMMS bloating; Functional constipation; Functional Hospital, Nazareth, Israel dyspepsia; Irritable bowel syndrome A. Mari Á M. Mahamid Faculty of Medicine in the Galilee, Bar-Ilan University, Ramat Gan, Israel DEFINITION D. Carter In 2016, the Rome IV working team revised the Department of Gastroenterology, Chaim Sheba Medical Center, Tel Hashomer, Ramat Gan, Israel Rome III diagnostic criteria and updated the clinical evaluation and treatment for functional & D. Boltin Á R. Dickman ( ) abdominal bloating and distension (FABD) [1]. Division of Gastroenterology, Rabin Medical Center, Beilinson Hospital, Petah Tikva, Israel According to the Rome IV, FABD is character- e-mail: [email protected] ized by (subjective) symptoms of recurrent abdominal fullness, pressure, or a sensation of D. Carter Á D. Boltin Á R. Dickman trapped gas (bloating), and/or measurable (ob- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel jective) increase in abdominal girth (distention) Adv Ther Table 1 Non-functional etiologies for abdominal bloating almost universal among patients with IBS [2]. and distension However only about half of the patients with bloating also report abdominal distension. In Celiac disease addition, bloating is more common among Lactose, fructose, and other carbohydrates intolerance patients with IBS, and distension is more com- mon in patients with chronic constipation [3]. Pancreatic insufficiency A telephone survey reported a prevalence of Gastroparesis 16% in US adults who were asked about bloat- ing or distension during the last month [4]. Diabetes mellitus Women were more likely than men to report Hypothyroidism bloating (19% vs 10.5%) and were more likely to Scleroderma have severe symptoms (24% vs 13%). However, other studies have not identified different Chronic idiopathic pseudo-obstruction prevalence rates of bloating by gender (21% and Small bowel bacterial overgrowth 19%) [3, 5]. Acute gastroenteritis Gastric malignancy PATHOPHYSIOLOGY Bowel malignancy The pathophysiology of FABD is multifactorial Ovarian malignancy and not completely understood. Several under- lying mechanisms have been proposed and may Ascites coexist in an individual patient (Fig. 1). Increased Intraluminal Content [1]. Bloating and distension may be the mani- Intraluminal content includes gas, air, water, festations of organic disorders which should be and fecal material. Air and gas may become diagnosed and treated separately. Common abundant within the lumen through aerophagia non-functional etiologies are listed in (Table 1). and potentially from overproduction of gas by Primary FABD should be diagnosed as a sin- colonic or small intestine bacteria [6]. Small gle entity (the sole or cardinal complaint) that intestinal bacterial overgrowth (SIBO), gas does not overlap with other functional gas- underabsorption, and diet high in fermentable, trointestinal disorders (FGID) such as functional poorly digested and absorbed carbohydrates constipation (FC), irritable bowel syndrome may all play a role [7]. However, recent studies (IBS), and functional dyspepsia (FD). However, have shown minimal, if any, differences in gas Rome IV diagnostic criteria permit the coexis- contents between IBS and healthy controls who tence of mild abdominal pain and/or minor consumed similar amounts of fermentable car- bowel movement abnormalities. Finally, symp- bohydrates [8, 9]. In another study comparing tom onset should be at least 6 months before gas contents using a novel abdominal CT diagnosis and the predominant symptom method, Accarino et al. did not find any change (bloating or distention) should be present dur- in the total abdominal volume during episodes ing the last 3 months [1]. of severe bloating, compared to baseline [10]. Therefore, on the basis of the mentioned stud- ies, excessive intraluminal gas is unlikely to be a EPIDEMIOLOGY major underlying mechanism for symptom generation in FABD. Bloating and distension have been reported by 30% of the adult general population and are Adv Ther Fig. 1 Algorithm for the approach and management of IBS irritable bowel syndrome, FC functional dyspepsia, abdominal bloating and distension. FGID functional SIBO small intestinal bacterial overgrowth gastrointestinal disorders, FC functional constipation, Visceral Hypersensitivity intraluminal contents. In fact, patients with IBS have an increased awareness of their gut con- Functional abdominal bloating and distension tents and motility, and may experience normal may originate from increased gut sensitivity or slightly altered gut intraluminal content as and abnormally increased attention to bloating [11]. In their comprehensive review, Adv Ther Malagelada et al. used the term ‘‘conscious per- Obesity ception’’ to explain the role of the brain–gut axis in symptom generation (abdominal bloat- Rapid weight gain and weight loss are associated ing). According to this model, visceral allodynia with aggravation and improvement in bloating, (seen also in IBS) is responsible for the bloating respectively [12]. In one study, recent weight sensation that occurs in the presence of normal gain coincided with new onset bloating in 25% or only mildly increased amounts of intralu- of the participants [5]. A possible mechanism minal gas or other bowel content [12]. may involve an abnormal viscero-somatic reflex originating in the abdominal adipose tissue Abdomino-Phrenic Dyssynergia which modulates the brain–gut axis, resulting in FABD [12, 19]. This term, coined by the Barcelona group, describes the response of patients with FABD to Dysbiosis a meal. According to studies by the group, patients with FABD have an abnormal muscle Aberrant constitution or alteration in colonic activity characterized by anterior abdominal microbacteria may lead to increased production wall relaxation and diaphragm contraction. of colonic gas by fermentation or decreased gas This activity redistributes abdominal gas, consumption, leading to increased colonic gas thereby causing an anterior wall protrusion and content and bloating [20]. Collins et al. found visible distension. This is in contrast to healthy that interruption of the host–microbiota equi- controls who in response to a meal experience librium affects the intestinal immune system contraction of anterior abdominal wall muscles and leads to inflammation. This, in turn, leads and relaxation of the diaphragm [10]. The rea- to gut sensory and motor dysfunction which son for this paradoxical maneuver in FABD is may contribute to bloating [21]. Others have not completely understood. It may be related to noted a relationship between colonic flora and an abnormal viscero-somatic response to the chemical composition of colonic gas. An innocuous intraluminal stimuli involving the interesting finding is that low producers of brain–gut axis. Regardless of its cause, the methane describe increased bloating following description of abdomino-phrenic dyssynergia ingestion of sorbitol and fiber [22]. Molecular represents a novel and major mechanism that analysis of fecal samples from IBS patients have may explain the occurrence of FABD [12]. failed to demonstrate a clear unifying texture for the IBS microbiome, but have revealed an Constipation and Outflow Obstruction increased ratio of Firmicutes to Bacteroidetes species [23]. More recently, Ringel-Kulka et al. Functional abdominal bloating and distension investigated the relationship between the may be related to constipation and to func- intestinal microbiota, abdominal bloating, and tional outflow obstruction. Retained stool in altered bowel patterns in a cohort of patients the rectum may cause impaired gas evacuation with IBS and found significant changes in and slowing of intestinal transit [13]. Compared microbiota among different IBS subtypes. In with healthy volunteers, patients with FABD particular, the authors noted that bloating was have a slower colonic transit [14]. Randomized associated