Functional indigestion (previously called nonulcer dyspepsia) is indigestion "without evidence of an organic disease that is likely to explain the symptoms". Functional indigestion is estimated to affect about 15% of the general population in western countries.
In most cases, the clinical history is of limited use in distinguishing between organic causes and functional dyspepsia. A large systematic review of the literature was recently performed to evaluate the effectiveness of diagnosing organic dyspepsia by clinical opinion versus computer models in patients referred for upper endoscopy. The computer models were based on patient demographics, risk factors, historical items, and symptoms. The study showed that neither clinical impression nor computer models were able to adequately distinguish organic from functional disease.
In a recent study, patients with peptic ulcer disease were compared with patients with functional dyspepsia in an age and sex-matched study. Although the functional dyspepsia group reported more upper abdominal fullness, nausea, and overall greater distress and anxiety, almost all the same symptoms were seen in both groups. Therefore, it is the clinician’s challenging task to separate patients who may have an organic disorder, and thus warrant further diagnostic testing, from patients who have functional dyspepsia, who are given empiric symptomatic treatment.The workup should be targeted to identify or rule out specific causes. Traditionally, people at high-risk have been identified by “alarm” features. However, the utility of these features in identifying the presence of upper cancer of the esophagus or stomach has been debated. A meta analysis looking at the sensitivity and specificity of alarm features found a range of 0–83% and 40–98%, respectively. However, there was high heterogeneity between studies.
The physical examination may elicit abdominal tenderness, but this finding is nonspecific. A positive Carnett sign, or focal tenderness that increases with abdominal wall contraction and palpation, suggests an etiology involving the abdominal wall musculature. Cutaneous dermatomal distribution of pain may suggest a thoracic polyradiculopathy. Thump tenderness over the right upper quadrant may suggest chronic cholecystitis.
In about 50-70% of patients with dyspepsia, no definite organic cause can be determined. In this case, dyspepsia is referred to as non-ulcer dyspepsia and its diagnosis is established by the presence of epigastralgia for at least 6 months, in the absence of any other cause explaining the symptoms.