**1. Introduction**

Dyspepsia is defined as predominantly midline pain or discomfort located in the upper abdomen [1]. Discomfort refers to a subjective, negative feeling that is not "painful". Dyspepsia can incorporate a variety of symptoms including early satiety or upper abdominal fullness. Although the term implies a relationship with eating and the majority of patients have symptoms worsened by food, this is no longer necessary to diagnose dyspepsia [2]. During the investigation of dyspepsia, three major structural causes are readily identifiable: peptic ulcer disease (10%), gastroesophageal reflux (20%) (with or without esophagitis), and malig‐ nancy (2%) [3]. Thus, most (50%-70%) patients with chronic dyspepsia do not have a significant focal or structural lesion found at endoscopy. When symptoms are chronic or recurrent (table 1) but without an identifiable structural cause using standard diagnostic tests (usually endoscopy), the condition is usually labelled functional or functional dyspepsia [4, 5]. Hence functional dyspepsia is a diagnosis of exclusion, the implication being that symptoms have been investigated without demonstrating an organic or anatomical cause [5].

Functional dyspepsia is not life-threatening and is not associated with any increase in mortal‐ ity. However, the impact of this condition on patients and health care services is considerable. In a recent community survey of several European and North American populations, 20% of people with dyspeptic symptoms had consulted either primary care physicians or hospital specialists; more than 50% of dyspepsia sufferers were on medication most of the time and approximately 30% reported taking days off from work or school due to their symptoms [5, 6]. Patients with functional dyspepsia have a significantly reduced quality of life when compared to the general population [7].

The Rome III criteria for diagnosing functional dyspepsia are persistent or recurrent upper abdominal pain or discomfort for a period of 12 weeks, which need not be consecutive, in the preceding 12 months, with symptoms present more than 25 percent of the time, and an absence

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**2. Functional dyspepsia: Pathophysiologic mechanisms and their relation**

Diagnostic Testing for Functional Dyspepsia http://dx.doi.org/10.5772/57088 3

Several pathophysiologic mechanisms explain underlie dyspeptic symptoms. These include delayed gastric emptying, impaired gastric accommodation to a meal, and hypersensitivity to gastric distension, *H. pylori* infection, altered response to duodenal lipids or acid, abnormal duodenojejunal motility, or central nervous system dysfunction. At present, the pathophysiol‐ ogy of functional dyspepsia is only partially elucidated. However, there is growing evidence that functional dyspepsia is in fact a very heterogeneous disorder and different subgroups can be identified based on different demographic, clinical, and pathophysiologic features [2].

Delayed gastric emptying is traditionally considered a major pathophysiologic mechanism underlying symptoms in functional dyspepsia and idiopathic gastroparesis [10]. Several large single-centre studies from Europe found association between delayed gastric emptying and the prevalence and severity of symptoms like post-prandial fullness, nausea, and vomiting [10]. Similarly, other reports have investigated the relationship between delayed gastric emptying and symptom pattern and severity [2]. Depending on the study, the percentage of dyspeptic patients with delayed gastric emptying ranges from 20% to 50%. In a meta-analysis of 17 studies involving 868 dyspeptic patients and 397 controls, significant delay of solid gastric emptying was present in almost 40% of patients with functional dyspepsia [11]. Various causes

The motor functions of the proximal and distal stomach differ remarkably. The proximal stomach (body) serves mainly as a reservoir. In contrast, the distal stomach (antrum) regulates gastric emptying of solids by grinding and sieving the contents until the particles are small enough to pass the pylorus. The stomach accommodates to a meal by relaxing of the proximal stomach, providing the meal with a reservoir and enabling an increase in volume without an increase in pressure. Scintigraphic and ultrasonographic studies have shown an abnormal intragastric distribution of food in patients with functional dyspepsia, with preferential accumulation in the distal stomach. These findings suggest defective postprandial accommo‐

Physiologic stimuli during the digestive process are not normally perceived but in some circumstances may induce conscious sensations. Patients with functional gastrointestinal diseases may have a sensory dysfunction of the gut (termed visceral hypersensitivity), with normal physiological stimuli perceived as discomfort or pain [14]. Patients with functional

The symptoms of dyspepsia are usually exacerbated by meals which are rich in fat [20]. Similarly the duodenum is more sensitive to acid in those with functional dyspepsia. The

dyspepsia appear to have enhanced sensitivity to gastric distension [10, 15, 16].

**to symptom pattern**

**1.** Delayed gastric emptying

of delayed gastric emptying are summarized in table 3.

**2.** Impaired gastric accommodation to a meal

dation of the proximal stomach [12, 13].

**3.** Hypersensitivity to gastric distension

**4.** Altered duodenal sensitivity to lipids or acid

**Table 1.** The spectrum of dyspepsia symptoms and recommended definitions [4, 5]

of clinical, biochemical, endoscopic, and ultrasonographic evidence of organic disease that would account for the symptoms [1] (Table 2).

12 weeks minimum, that need not be consecutive, in the preceding 12 months of:

• Persistent or recurrent symptoms (pain or discomfort centred in the upper abdomen);

• No evidence of organic disease (including at upper GI endoscopy) that is likely to explain the symptoms;

• No evidence that dyspepsia is exclusively relieved by defecation or associated with the onset of a change in stool frequency or stool form (i.e., not irritable bowel).

**Table 2.** Rome III diagnostic criteria for functional dyspepsia [1, 9]

On the basis of the most bothersome or predominant single symptom, identified by the patient, functional dyspepsia is further classified into various subgroups [4, 9]:

**1.** Ulcer-like dyspepsia

Pain centred in the upper abdomen is the predominant (most bothersome) symptom [9].

**2.** Dysmotility-like dyspepsia

An unpleasant or troublesome non-painful sensation (discomfort) centred in the upper abdomen is the predominant symptom; this sensation may be characterized by or associated with upper abdominal fullness, early satiety, bloating, or nausea [9].

**3.** Unspecified (non-specific) dyspepsia

Symptoms do not fulfil the criteria for ulcer-like or dysmotility-like dyspepsia [9].
