Borborygmus, plural borborygmi, is the gurgling sound made by normal bowels. It is also known as stomach growling or stomach rumbling. The sound occurs when gas moves through the gut, pushed along by waves of muscle contraction in the intestinal wall. These contraction waves are known as peristalsis and are what propel food along inside the gut. A louder borborygmus may be heard when one is hungry or anxious, as the stomach may then contract rapidly and move the contents of the gut back and forth.
Gases commonly found inside the gut include carbon dioxide from the stomach juices, oxygen and nitrogen taken in via the mouth, and hydrogen and methane produced by bacterial fermentation in the colon. Borborygmi are altered or absent in a number of diseases. Listening for them, with a preferably warmed stethoscope placed on the abdomen, can be an important part of the diagnostic process.
Air is taken in when talking or swallowing food and drink, and this can create a borborygmus further along the gastrointestinal system. Ordinarily, gas is produced in the gut when food is broken down by bacteria and enzymes. Sometimes eating foods such as cabbage or beans, which are high in fiber and take longer to digest, can lead to increased accumulation of gas. Alternatively, a sudden change in diet may lead to increased gas, as gut bacteria which were appropriate for the habitual diet are not optimized to digest the new food substances.
With more gas, as well as increased borborygmus frequency and loudness, there may be associated feelings of bloating together with belching and flatulence. Although borborygmi are usually harmless, altered levels are particularly associated with a number of diseases. Disorders where food is not absorbed properly by the gut, such as celiac disease, or those where the bowel is inflamed such as diverticulitis, can cause an increase in gas and bowel sounds. Irritable bowel syndrome is another possible cause of this, as is a stomach infection, or gastroenteritis. Certain drugs, such as laxatives, may also lead to excess noisy gas in the gut.
In more serious conditions, where part of the intestine becomes obstructed, perhaps by a tumor or a strangulated hernia, a swollen cramping abdomen may be accompanied by high-pitched borborygmi and vomiting. The high-pitched sounds are a result of increasing waves of peristaltic contraction approaching the obstruction, in combination with a distended gas-filled intestine. Patients are usually admitted to the hospital for emergency surgery.
As it progresses, bowel obstruction eventually leads to an absence of bowel sounds. Blood flow to the gut is compromised, peristalsis ceases and the bowel is effectively paralyzed. As normal bowel sounds may be infrequent, it is important to listen for long enough to ensure that borborygmi are truly absent, perhaps for around three minutes or so.