Carbohydrates not absorbed in the small intestine are fermented by colonic bacteria to organic acids and gases(e.g. carbon dioxide, hydrogen and methane), part of which is absorbed in the colon, the other part remaining in the lumen. Large interindividual differences have been demonstrated for the production of such acids and gas. Carbohydrate malabsorption can be diagnosed by using the hydrogen breath test, because the gases produced after administration of a provocative dose of carbohydrate are unique products of bacterial carbohydrate fermentation.

Familial Mediterranean fever (FMF), also called periodic disease, Armenian disease, etc., is a prototypical autoinflammatory disorder where the underlying mechanism is the dysfunction of innate immunity, resulting in unprovoked episodes of inflammation.¹ Although considered rare worldwide, it is prevalent in people of Mediterranean origin; however, one can expect to encounter patients in all parts of the modern world. FMF is a monogenic disease with autosomal recessive inheritance.² Unlike other monogenic disorders, the diagnosis remains largely clinical, and it is important to understand the limitations of genetic testing. Another distinguishing feature is the well-established effectiveness of lifelong monotherapy with colchicine in preventing attacks and complications.³

Abdominal distension and bloating are among the most frequently misunderstood complaints in gastroenterology. They are often used as interchangeable terms, a conceptual mistake that continues to drive diagnostic errors and ineffective treatment. According to Rome IV, bloating and distension may represent either a primary disorder of gut–brain interaction (DGBI) or occur as symptoms with other DGBIs, such as irritable bowel syndrome (IBS), functional dyspepsia (FD) or functional constipation (FC).

A recent UEG survey indicated that dysphagia, heartburn, bloating, abdominal pain and changes to bowel habit are each reported by 5–15% of the general population.1 For patients with mild symptoms, negative tests provide reassurance and simple, symptomatic management might be all that is required (e.g. acid suppression, stool regulation). However, for those with severe symptoms that persist on therapy, ruling out life-threatening disease is not sufficient, and referral to the neurogastroenterology and motility (NGM) laboratory for physiological measurements is often indicated. Clinical investigations aim to explain the cause of symptoms and establish a diagnosis that can guide rational treatment. Until recently, it could be argued that manometry, scintigraphy, breath tests and related tests rarely provided this information. As a result, only patients with suspected major motility disorders (e.g. achalasia, severe reflux disease or faecal incontinence) were routinely referred to the NGM laboratory for tests. Technological advances, such as high-resolution manometry (HRM), now provide objective measurements not only of motility, but also of function in terms of the movement (and digestion) of ingested material within the gastrointestinal tract. Furthermore, the ability to associate events (such as bolus retention, reflux or gas production) with symptoms provides an indication of visceral sensitivity and can identify what is causing patient complaints. Here, I discuss frequent mistakes in clinical investigation of gastrointestinal motility and function based on a series of consensus documents published by members of the International Working Group for Disorders of Gastrointestinal Motility and Function.