The Link Between Peristalsis and Motility Disorders

When certain muscles in the digestive and urinary tracts contract, it is called peristalsis. Peristalsis is a particular, wave-like kind of muscle contraction because its purpose is to move solids or liquids along within the tube-like structures of the digestive and urinary tracts. Peristalsis is not a voluntary muscle movement, so it's not something people can control consciously. Rather, the smooth muscles involved in peristalsis operate when they are stimulated to do so.

Peristalsis is important to digestion, but sometimes it doesn't work properly. Having constant diarrhea or constipation could be a sign that something has gone haywire with peristalsis. This can be caused by a medication, but it could also be from a condition that is called a motility disorder. Motility disorders can be challenging to treat, so it's important to see a digestive specialist, a gastroenterologist, to find solutions.

Peristalsis in the Digestive Tract

Peristalsis in the digestive tract begins in the esophagus. After food is swallowed, it is moved down the esophagus by peristalsis. The muscles in the stomach, small intestine, and large intestine continue the process. Food is further digested and broken down as it moves through the digestive tract, aided by digestive juices that are added along the way. Bile, which is an important part of the digestive process, is produced in the gallbladder and is moved from the gallbladder into the duodenum (a section of the small intestine) via peristalsis. At the end of its journey through the body via peristalsis, the digested food is excreted through the anus as stool.

Peristalsis in the Urinary Tract

Urine is also moved along through the body with the help of peristalsis. Two tubes in the urinary tract called ureters use peristalsis to move liquid from the kidneys to the bladder. This liquid then leaves the body through the urethra as urine.

Peristalsis and Motility Disorders

When peristalsis does not occur as it should, it can result in one of a group of conditions called motility disorders. In some people, peristalsis may go too quickly, known as hypermotility, or too slowly, known as hypomotility. Motility disorders can occur for a variety of reasons, including a side effect of a medication, a result of another disease process, or even for no known cause (which is called idiopathic). People with inflammatory bowel disease (IBD) may also have motility disorders, but it's unknown at this time how these conditions may be related, and how often they may occur together.

Some examples of motility disorders include:

• Dysphagia. In dysphagia, the peristalsis in the esophagus is affected, and people with this condition find that it is difficult or impossible to swallow foods and liquids.
• Esophageal spasms. There are a few different forms of disorders that can cause spasms of the muscles in the esophagus. Spasms can be intermittent and/or severe and may result in regurgitation of food. 
• Gastroesophageal reflux disease (GERD). GERD may also have a connection with impaired motility, but the relationship is still under study.  
• Gastroparesis. With this condition, it is the muscles of the stomach that are not moving food along into the small intestine. This can result in symptoms of nausea and vomiting. There are many potential causes, but in some cases, the cause is not known.
• Intestinal pseudo-obstruction. An obstruction occurs when the movement of food through the bowels is impeded by something, such as a narrowing of the intestine or impacted stool. However, in pseudo-obstruction, there is no blockage present, yet the digestive system is impaired just as if there were a mechanical blockage. This is an uncommon condition.
• Irritable bowel syndrome (IBS). People with IBS may also experience hypermotility, hypomotility, or both in succession. Symptoms can include diarrhea or constipation. How motility fits into the diagnosis and treatment of IBS is still not well understood, but more research is being done.