Bowel Sounds

Sounds that are produced by movement of the contents of the gastrointestinal tract are known as bowel sounds. This HealthHearty article describes what do normal, hypoactive, hyperactive, and absent bowel sounds indicate.
HealthHearty Staff
Last Updated: Jan 21, 2018
The word bowel sound is employed to denote the gurgling or rumbling sound that is emanated from the abdomen. Food passes from the stomach into the intestines, and this movement is brought about by the contraction of muscles (peristalsis) of the digestive tract. The sound made by movement of digested/undigested food in the lower gastrointestinal tract is known as bowel sound. There are different types of bowel sounds, and for the astute internist, these are clear telltale signs of a possible underlying bowel problem. These sounds are also known as abdominal / peristaltic sounds, stomach rumble, or borborygmus. They may be loud enough to be heard with bare ears, or you can hear them with the help of a stethoscope.
Normal Bowel Sounds
When assessing abdominal sounds, you need to take your stethoscope, and place it on all four quadrants. Usually, the bowel sounds are heard very clearly in the lower right quadrant, which is where the ileo-cecal region is. Normal bowel sound is heard as high-pitched and slightly gurgling-like sound. These sounds are produced due to mixing of gas/air with fluid during peristaltic movement of the muscles. Most bowel sounds are normal and harmless. Needless to say, these sounds are loudest just before mealtimes (which is why our stomach 'growls' when we're hungry).
Hyperactive Bowel Sounds
Hyperactive sounds of the bowel are heard as 'loud and very high-pitched' sounds. Also, the frequency of these sounds is very high. These are mostly indicative of conditions like diarrhea, wherein the bowel movement rate and frequency is high. Other diseases where hyperactive abdominal sounds are heard include:
Crohn's disease, where there is idiopathic inflammation of the gastrointestinal tract.
Irritable bowel syndrome and ulcerative colitis also lead to an increase in bowel sound.
Sometimes, food allergy and gastroenteritis may also lead to hyperactive sounds emanating from the bowel.
Ingestion of milk by a person, who is lactose intolerant, and consumption of gluten by a person, who is diagnosed with celiac disease, can lead to exaggerated bowel sounds.
Hypoactive Bowel Sounds
A reduction in the intensity, volume, or regularity of the sounds indicates that the intestinal activity has slowed. Hypoactive sounds are heard relatively infrequently. These sounds signify many conditions including:
Peritonitis, in which there is inflammation of the peritoneum. Here, due to the inflammation, there may be accumulation of slight fluid in the abdomen, and so, the abdominal sounds are not heard as clearly over it.
When there is accumulation of fluid in the abdominal region, it is known as ascites. Due to the presence of this fluid, the abdominal sounds get muffled, and so, seem to be hypoactive.
When there is any kind of obstruction to flow of food, in the form of intestinal blockage or gastroparesis (damaged vagus nerve, stomach cannot empty itself of food in a normal way), then it leads to hypoactive sounds of bowel.
Hypoactive sounds may occur for a short time after the use of certain medicines.
They can be heard after abdominal surgery.
Constipation is a common cause of decreased or no bowel sounds.
Absent Bowel Sounds
There may be a few cases wherein abdominal sounds may be completely absent. One cannot say that bowel sounds are absent unless and until no sounds are heard from the abdomen on auscultation for a minimum of three minutes.
When a person is sleeping, there may not be any activity of the gastrointestinal tract, due to which, no sound may be heard. Hypoactive or absent bowel sounds during sleep are considered to be normal, and there is no need for people to feel that this may be an indication of an underlying disease or disorder.
But there are certain conditions when bowel sound may be absent. Ileus is a condition in which there is a lack of intestinal activity. Several disorders can lead to ileus. Accumulation of the contents of the intestines can cause gas and fluids, and can eventually rupture the bowel wall.
After a surgery, abdominal sounds may not be heard, because it takes time for the general anesthesia to wear off. So, there is usually no bowel movement for a while after any kind of surgery that employed general anesthesia.
Although auscultating for sounds coming from the bowel can be an important indicator of an underlying digestive system disease, one needs to also do other tests to reach a final diagnosis. Various conditions like gastrointestinal bleeding, radiation to the abdomen, paralytic ileus (nerve problem), blocked blood vessels, hernia, tumor, adhesions, indigestion, etc. can change the nature of bowel sounds. Once the underlying condition has been zeroed in, should a treatment plan be meted out.
Disclaimer: The information provided in this article is solely for educating the reader. It is not intended to be a substitute for the advice of a medical expert.