Functional dyspepsia or gastroparesis? A guide to assessment, investigation and management

Patients presenting with upper gastrointestinal symptoms such as postprandial fullness, early satiation, epigastric pain or burning, upper abdominal bloating, nausea and vomiting often receive the diagnoses of functional dyspepsia (FD), a disorder of the gut–brain interaction, or gastroparesis, a gastric motility disorder. The diagnosis of FD is largely symptom-based, using the Rome IV criteria, while for gastroparesis, establishing delayed gastric emptying (GE) in the absence of gastric outlet obstruction is necessary. However, symptoms of FD and gastroparesis can be indistinguishable, as well as certain pathophysiological mechanisms (ie, delayed GE, impaired gastric accommodation, visceral hypersensitivity) and treatments (ie, antiemetics, prokinetics, neuromodulators). Thus, the presentation and diagnosis of both FD and gastroparesis in clinical practice can be challenging for providers. Moreover, numerous studies have demonstrated that the severity of symptoms does not necessarily correlate with the degree of delay in GE. It has also recently been shown that patients often transition between diagnoses based on the volatile nature of GE test results. This calls for a reconceptualisation of these diagnostic entities. The aim of this review is therefore to perform a critical appraisal of similarities and differences between FD and gastroparesis and to provide a practical guide for the practising clinician.