Stomach growling and other digestive noise

For centuries, people have associated noises that arise from the upper abdomen (often assumed to be from the stomach) with hunger. But that's not the only time noise comes from the intestinal tract. Do you ever wonder why, or whether it could be a sign of illness? And why should your stomach growl when you're hungry?

Then there's burping. We encourage babies to burp, yet it's viewed as rude for adults to burp in public in this country. In others, it's a compliment to the chef. Why do people burp? And is it harmful to suppress a burp?

Digestion is a noisy process

Noises from the upper digestive tract have probably been recognized as soon as humans appeared on this planet. Some of the earliest physicians wrote scholarly treatises on bowel sounds and naturally, doctors have applied technical terms to these:

• Burping is called eructation, and describes the act of expelling air from the stomach.
• Loud rumbling or gurgling from within the abdomen (often referred to as "stomach growling") is called borborygmi and may reflect the normal actions of the stomach and intestines to propel food through the digestive tract (called peristalsis). Interestingly, the exact source of bowel sounds is uncertain, but they are thought to occur as gas moves around propelled by the muscular contractions of the intestinal walls.
• Expelling gas through the rectum and anus is called flatus. It goes by many other names, of course - just ask your kids.
• The sloshing of liquid within the intestinal tract is common, but is particularly easy to detect with a stethoscope after surgery or with a blockage, when the intestine is not working well to move its contents along. Doctors call this sound a succussion splash.

Digestive noises in health

Three hundred years ago, British experimental scientist Robert Hooke wrote the following:

"It may be possible to discover the motions of internal parts of bodies" by listening to the "motion of the wind to and fro in the guts."

So far, Hooke's statement turns out to be an overestimation of what intestinal sounds can tell us; however, the notion that digestive noises can reflect the state of one's health clearly goes back centuries.

It is normal to have some air in the digestive tract. Some air is swallowed, and some is produced by bacteria in the intestines and by the process of digestion. It is also normal for the body to periodically get rid of some air; burping or passing gas helps keep the pressure within the intestinal tract low and prevents painful stretching of the stomach, small intestine, or large intestine. But that process is often accompanied by noise, and, depending on the situation, those noises may be viewed as embarrassing or inappropriate.

Babies swallow air during feeding; patting the back while keeping them upright helps make that bubble of air in the stomach rise to the top and escape through burping. Adults also swallow air, especially while drinking carbonated beverages. Trying to suppress a burp is unlikely to cause harm, though it may be unpleasant.

The stomach and intestines move food along from top to bottom by the process of peristalsis: the tubelike small intestine or large intestine squeezes in an organized, sequential fashion (a bit like squeezing a tube of toothpaste) to allow digestion to occur and to keep the intestinal contents moving along. Often air and liquid are mixed up and rearranged in this process, causing odd noises to be audible. When a doctor puts a stethoscope on the abdomen, he or she can often hear borborygmi, an entirely normal finding.

Imagine a long, thin balloon (the type clowns use to make animal shapes), half filled with water. If you jostle the balloon enough, you'd be able to hear splashing or sloshing sounds - that's what happens if you drink several glasses of water and then jump on a trampoline. A succussion splash simply reflects the movement of liquid within a tube - in this case, the intestines.

Flatus is also normal because as food and waste products move through the digestive tract toward the rectum, any trapped air will be pushing ahead of it, eventually being expelled. Certain foods will increase the amount of intestinal air produced during digestion because they do not break down until they reach the large intestine, where bacteria digest the food and create gas in the process, unlike with other foods digested higher up in the intestinal tract.

Beans have a reputation for causing gas, but so do cabbage, Brussels sprouts, broccoli, cauliflower, peas, oat bran (and other high-fiber foods), carbonated beverages, and foods containing sorbitol (an artificial sweetener present in many low-calorie foods). Fructose, a natural sugar present in many fruits (including prunes, pears, grapes, dates, and figs) and in many sweeteners is also associated with increased intestinal gas.

All of these noises are normal, but if you have abdominal pain, doctors will actually worry more when borborygmi and flatus are absent than when they are present. That's because their absence could indicate a perforation or a section of nonfunctioning bowel.

Because of all the ways the digestive tract can create noises, a noisy abdomen does not necessarily mean you are hungry; a much more reliable sign is actually feeling hungry.

Digestive noises in disease

Although burping is almost always normal, there are rare occasions when it is a sign of illness. In patients with a partial or complete blockage in the digestive tract, the only way for air to escape is upward, by burping. Some people who are having heart problems, including a heart attack, may have prominent burping (or nausea) because the heart's nerve supply overlaps that of the upper digestive tract. That's why "indigestion" sometimes turns out to be heart trouble. Gastroesophageal reflux disease (or GERD) is a condition in which frequent or severe heartburn, related to acidic stomach contents entering the lower esophagus, may cause discomfort and burping.

A growling stomach may growl louder, high-pitched, or even sound "tinkling" if there is an infection (as is common in gastroenteritis related to a viral infection), or a partial or complete blockage (called obstruction) as the intestines try to push fluid, gas, and waste products past the trouble area. When borborygmi increase due to obstruction, other symptoms are typically present, such as bloating, crampy pain, nausea, and vomiting, that make it clear that these "normal" sounds are not due to the normal course of events.

Conversely, hearing no bowel sounds, especially when abdominal pain is present, could be an indication of an inflamed pancreas (called pancreatitis), peritonitis (inflammation of the lining of the abdomen, usually an indication of serious trouble in the abdomen), or a perforation (a tear in the bowel wall). An exceptionally quiet digestive tract is typical of anyone who has just come out of major surgery, because the normal movement of the bowel wall is temporarily paralyzed after a major trauma such as surgery. This condition is called ileus.

Increased flatus could be due to lactose intolerance, intestinal infection, irritable bowel syndrome, or other, less common conditions. Medications sometimes cause increased flatus as well. As mentioned, diminished or absent flatus may mean the digestive tract is not moving at all (as in ileus) or is obstructed, a more serious problem.

The bottom line

Noise that arises from the digestive tract is not just a fact of life, it's usually a sign of health. Your doctor may listen over the abdomen with a stethoscope, but it is often easy to hear noises even without one. If you have concerns about your digestive tract or the noises it makes, see your doctor for evaluation, especially if you also have abdominal pain. But don't assume that whenever your stomach growls, it's time to eat; doing so may do little to reduce the noise but much to increase your weight.

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