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Abdominal distension is the most commonly reported gastrointestinal problem and is often related to abdominal bloating.
Although interrelated, bloating and distension have separate pathophysiological explanations; precisely, bloating is the symptom and distension is the sign of gastrointestinal disorders, such as irritable bowel syndrome (IBS) and other functional gastrointestinal disorders. In IBS, about 50% of the patients who report about bloating actually suffer from abdominal distension.
Abdominal distension is a visible increase in abdominal girth, which can be measured by tape, X-ray, computed tomography, and abdominal inductance plethysmography. Both abdominal bloating and distension have been reported in about 96% of patients with IBS and 20 – 30% of the general population.
Although bloating is more common in IBS patients, distension is more related to constipation and pelvic floor dysfunction.
The most common symptoms of distension are aerophagia, flatulence, and burping, which often cause discomfort and pain, as well as exert negative impact on the quality of living.
Mechanistically, it is found that, in patients with intestinal motility disorder, an increase in abdominal content during abdominal distension is associated with increased abdominal diameter and cephalic displacement of the diaphragm. As a compensatory mechanism, antero-posterior diameter of the chest increases to overcome the consequences associated with reduced air volume of the lung.
In infants, abdominal distension is a common metabolic disorder, which may be life-threatening in some worst conditions. It is found that, in about 45% of premature infants and 62% of full-term infants, congenital malformations are the leading cause of abdominal distension.
Of these malformations, congenital megacolon and sepsis are the primary causes of distension in full-term and premature infants, respectively. The main symptom of distension is vomiting. As evidenced from the X-ray analysis, the signs of distension are more severe in premature infants due to the presence of an air-fluid level – a characteristic feature caused from the accumulation of gas and liquid in the intestine.
In order to identify effective treatment strategies, it is important to assess the causative factors of bloating and/or distension. This can be done by checking the dietary habit and monitoring the frequency and consistency of stool. Evaluation of the abdominal shape by imaging techniques during distension is also effective. In some severe cases, it is important to check the motility, visceral sensitivity, and abdominal muscle activity in response to gastrointestinal tract stimuli.
To date, the most useful interventions to treat bloating and/or distension include:
Diet – a diet that contains lower amount of poorly absorbed short-chain carbohydrates, such as fructans, lactose, fructose, sorbitol, and mannitol, are considered as the most effective strategy to reduce bloating and distension episodes associated with IBS.
Laxatives – since one of the leading causes of distension is constipation, use of laxatives to manage regular bowel movement is a common strategy to reduce abdominal distension.
Prosecretory and promotility agents – linaclotide, prucalopride, and lubiprostone are considered as effective medicines to treat constipation and reduce bloating and/or distension.
Antibiotics – since carbohydrate fermentation by bacteria is a major cause of gas formation in the intestine, use of antibiotics, such as rifaximin and neomycin, are helpful in reducing the episodes of bloating and distention.
Alternative medicines – simethicone, charcoal, kiwifruit extract, etc are also helpful in reducing intestinal gas formation and improving bowel movement; thus, considered as effective measures to reduce bloating and/or distension.