Diagnosis of Functional Dyspepsia and Novel Gastrointestinal Functional Assessments.

backgroundFunctional dyspepsia (FD) is a common disorder of gut-brain interaction characterized by postprandial distress and epigastric pain, which significantly impairs quality of life and increases healthcare burden. Although the Rome IV criteria and Japanese guidelines have refined its definition, the pathophysiology remains multifactorial, involving gastric motility abnormalities, visceral hypersensitivity, and autonomic dysfunction. Traditional diagnostic approaches, mainly based on clinical history and exclusion of organic diseases, are limited in elucidating the underlying mechanisms. SUMMARY: Recent advances in gastrointestinal functional assessments have enabled more detailed evaluation of gastric accommodation, emptying, motility, and sensory function. Techniques such as barostat, antroduodenal manometry, gastric scintigraphy, and gastric emptying breath tests have been established in research settings, while newer modalities - including cine magnetic resonance imaging, body surface gastric mapping (BSGM), and wireless motility capsule (WMC) - offer noninvasive and comprehensive insights into gastric motor and sensory function. Furthermore, the use of endoscopy-based functional testing has expanded diagnostic capabilities. Autonomic nervous system testing, including heart rate variability analysis and exploratory wearable device approaches, provides additional perspectives on the gut-brain axis. Collectively, these tools have advanced the understanding of FD pathophysiology; nonetheless, their availability and standardization remain limited. KEY MESSAGES: FD is highly prevalent and burdensome, with a complex and multifactorial pathophysiology. A wide range of gastrointestinal functional tests has been developed from established barostat and scintigraphy to emerging noninvasive methods such as cine magnetic resonance imaging, endoscopy-based functional testing, WMC, and BSGM. These novel approaches can capture both motor and sensory abnormalities, offering new opportunities for personalized management of FD. Standardization, validation, and wider clinical implementation of these functional assessments are needed to translate research advances into routine practice.