Irritable stomach syndrome, also called functional dyspepsia, is one of the most common functional gastrointestinal disorders. The term "dyspepsia" (from Greek: dys = bad, and pepsis = digestion) is used to summarize a spectrum of complaints that the patient localizes in the upper abdomen (between the umbilicus and the xiphoid process) and laterally. According to the Rome IV criteria (Talley NJ 2016), functional dyspepsia is defined by:
- persistent or recurrent dyspepsia for more than three months within the last six months.
- lack of evidence of an organic cause in the endoscopic clarification, which could explain the complaints
- lack of evidence that the dyspepsia is relieved solely by defecation or is associated with stool irregularity (this criterion was introduced to exclude a possible causative irritable bowel syndrome (IBS) for the complaints).