Flatulence and Wind

Flatulence, wind and bloating are symptoms related to gas in the gastrointestinal system. 'Flatulence' usually refers to gas passed per rectum. 'Wind' as a symptom may mean either belching (gas passed from the stomach outwards via the mouth), or gas passed per rectum. In some cases patients may use 'wind' to refer to abdominal noises or bloating. 'Bloating' generally means a sensation of abdominal distention, possibly with discomfort.

Belching

Alternative term: eructation. This is the release of gas from the stomach, either voluntary or involuntary. It is a normal reflex which occurs most commonly after meals, releasing swallowed air.

• Belching can be associated with eating too quickly, fizzy drinks, chewing gum and smoking. Bicarbonate/antacid ingestion (which produces carbon dioxide gas) may contribute. Belching may also be due to excessive aerophagia (swallowing air), which can occur unnoticed while eating or chewing.¹
• Aerophagia may occur in response to dyspepsia symptoms, which are misinterpreted by the patient as due to gas in the stomach. This can lead to a cycle of repeated attempted belching and air swallowing.²
• Malodorous belching may be due to giardiasis, which can causes sulphurous (egg-smelling) breath.

Flatulence

Intestinal gases come from three sources: swallowed air, carbon dioxide from gastric acid neutralisation, and intestinal bacteria colonies that produce carbon dioxide, hydrogen and methane.³ The volume and composition of gas depends both on diet and on colonic flora; the flora vary between individuals. A large volume of gas probably does not cause symptoms in healthy people, because it is easily expelled.²

Symptoms of flatulence may be related to:

• Constipation - because faecal retention prolongs the fermentation process.²
• Diets rich in carbohydrate and certain vegetables (the cabbage family and pulses such as beans).
• Sugar intolerance: lactose intolerance is well recognised.⁴ Certain other carbohydrates may not be well absorbed and these include:
  • Sorbitol (a sweetener in sugar-free products)
  • Fructose (found in fruits, honey and soft drinks)
• Infections: gastroenteritis may alter gut bacteria and hence gas composition.
• Malabsorption

Bloating and distention

Research into mechanisms underlying abdominal bloating symptoms has been mainly in people with irritable bowel syndrome. It suggests that the volume of intestinal gas is not increased compared with healthy people. Nevertheless, distention (increased abdominal girth) has been documented to be genuine and measurable. Usually there is diurnal variation, with symptoms worst in the evening.² The bloating symptoms are probably due to a combination of:

• Impaired propulsion of small bowel contents (in the proximal small bowel), which causes focal pooling of bowel contents and focal distention. Fats seem to increase this effect.⁵
• Increased sensitivity to bowel stimuli.
• Abdominal wall reflexes. Normally, in response to a colonic load, the diaphragm relaxes and the abdominal wall contracts so as to keep the abdominal girth stable. This reflex seems to be reduced in people complaining of bloating.²

• Constipation
• Gastroenteritis, giardiasis
• Malabsorption
• Inflammatory bowel disease
• Subacute obstruction
• Abdominal or pelvic malignancy
• Eating disorder or laxative abuse
• Anxiety, depression or somatisation contributing to symptoms
• Endocrine e.g. Cushing's syndrome, hypothyroidism

Symptoms and signs

• Clarify what the patient means, as the lay person's language used for these symptoms varies considerably, and communication may be hampered by embarrassment.
• Find out what most bothers the patient about their symptoms.
• Ask about 'alarm symptoms': dysphagia, weight loss, rectal bleeding or melaena, vomiting, fever. Any persistent increase in abdominal girth, out of proportion to general body fat (e.g. such that it causes clothes to be too small), should raise the thought of an abdominal mass, ascites or endocrine disorder.
• Diet enquiry may be relevant, including fizzy drinks, artificial sweeteners and chewing gum.
• Examine for general signs and anaemia; abdominal examination for masses or ascites; rectal examination if relevant.

• For a patient with persistent abdominal symptoms, it is reasonable to request blood tests for: a full blood count, ESR/CRP, renal function, glucose, liver function and calcium.
• Coeliac antibody testing, including IgA levels, is relevant for irritable bowel type symptoms, anaemia or suspected malabsorption.⁶
• Significant results are anaemia, iron deficiency, raised ESR or CRP, abnormal liver function tests or calcium. These require further investigation.
• 'Alarm symptoms' (above) and significant results require further investigation.

General

• Exclude important pathology by clinical assessment and investigations if appropriate, but avoid over-investigation.
• Recognise how symptoms are affecting the patient's life.
• Explanation and reassurance are important, as patients often worry about bowel cancer.

Belching²

Explanation of normal physiology and reassurance is usually sufficient. Investigate/treat dyspepsia symptoms if relevant.

Flatulence and bloating

Note that most of the research and literature on this topic relates to patients diagnosed with irritable bowel syndrome. Possible treatments include:

• Treat exacerbating factors such as constipation.
• Mild exercise - may improve intestinal gas clearance and reduce symptoms, one study found.⁷
• Probiotics: these are 'gut friendly' bacteria such as lactobacilli and bifidobacteria.^8,9 The specific strain of bacteria may be important.¹⁰
• Dietary modification benefits some patients. Foods likely to worsen symptoms are: large amounts of insoluble fibre such as bran; chocolate, coffee, fructose and sweeteners. Other foods may be tested by excluding one at a time for about a month. Dietician advice may help.¹⁰
• One study tested an oral antibiotic, rifaximin, which is has little systemic absorption. Rifaximin seemed to benefit bloating and flatulence symptoms.¹¹

Other treatments for flatulence

• Enzymes may help, for example, alpha-galactosidase reduced gas production following a bean meal.¹²
• Garment devices containing activated charcoal, which absorbs odour, have been tested in one trial. This found that briefs containing charcoal were effective, but pads and cushions of the same material were less so.¹³

Other treatments for bloating

• Antispasmodics and other treatments have traditionally been used to treat irritable bowel syndrome pain,¹⁰ but their role in bloating specifically is not clear.
• One small trial found that acupuncture improved postoperative abdominal distention.¹⁴