Motility studies are specialized diagnostic tests that measure the movement of the digestive tract. Motility refers to the muscle contractions, called peristalsis, that propel food and waste through the gastrointestinal (GI) tract from the esophagus to the rectum. When these contractions are too fast, too slow, or uncoordinated, they cause digestive symptoms. Doctors use these studies to determine precisely where in the digestive system movement is not functioning correctly, which guides effective treatment.
Understanding Digestive Motility Studies
A digestive motility study quantifies the mechanical performance of the GI muscles. The tests measure the strength, speed, and coordinated timing of muscle contractions and the pressure within digestive organs. This information provides a functional map of how the body processes food, which is often not visible through standard imaging like X-rays or endoscopy.
Abnormal motility, or dysmotility, occurs when the nerves or muscles controlling movement do not work together properly. This can result in food moving too slowly (hypomotility) or too quickly (hypermotility). Identifying the specific nature and location of this muscle dysfunction is the goal of these specialized studies.
Symptoms and Conditions That Require Testing
Doctors typically order a motility study when a patient experiences chronic, unexplained symptoms that persist despite standard treatments. Common indicators include persistent difficulty swallowing (dysphagia), chronic nausea, vomiting, or feeling full immediately after starting a meal. These studies are also warranted for patients with chronic reflux or heartburn that does not respond to standard medication, suggesting a muscle-related issue in the esophagus. Additionally, long-term, severe constipation that resists laxatives often points toward a lower GI motility problem. These persistent symptoms signal an underlying functional disorder.
Motility studies diagnose specific functional disorders after structural problems have been ruled out. Upper GI tract tests can confirm conditions like gastroparesis, where the stomach empties too slowly, or achalasia, where the lower esophageal sphincter muscle fails to open properly. Lower GI tract studies help identify causes of chronic constipation, such as pelvic floor dysfunction or colonic inertia, where large intestine muscle activity is reduced. Other conditions diagnosed include chronic intestinal pseudo-obstruction, caused by nerve or muscle failure, and functional dyspepsia.
Types of Motility Tests and Procedures
The methods used to measure GI motility are tailored to the specific area of the digestive tract being evaluated.
Esophageal Motility
Esophageal manometry is the standard test for the swallowing tube. It uses a thin, pressure-sensitive tube inserted through the nose and into the esophagus. This procedure measures the force and coordination of muscle contractions as the patient swallows water. High-resolution manometry provides detailed, color-coded images of pressure dynamics, allowing doctors to diagnose conditions like esophageal spasms or achalasia based on muscle function.
Gastric and Small Intestine Motility
Gastric Emptying Scintigraphy (GES)
To assess stomach emptying, Gastric Emptying Scintigraphy (GES) is often used. The patient consumes a standardized meal containing a small amount of a radioactive tracer. A camera takes images over four hours to track how quickly the meal moves out of the stomach.
Wireless Motility Capsule (SmartPill)
Alternatively, the SmartPill wireless motility capsule is swallowed and transmits data on pressure, temperature, and pH as it travels through the GI tract. This non-invasive method measures transit time throughout the entire GI tract, assessing gastric, small bowel, and colonic emptying times.
Antroduodenal Manometry
Antroduodenal manometry uses a catheter with pressure sensors placed into the stomach and the first part of the small intestine. This measures muscle activity patterns during both fasting and after a meal. This test is useful for identifying disorders where the stomach and small intestine fail to coordinate their contractions.
Colonic and Anorectal Motility
For problems related to the large intestine and rectum, specialized studies are performed.
Colonic Transit Study
A Colonic Transit Study involves swallowing capsules containing small, visible markers. X-rays are taken over several days to track their movement through the colon. This procedure helps determine if slow transit is the cause of chronic constipation.
Anorectal Manometry
Anorectal manometry evaluates the muscles and nerves controlling bowel movements. A thin, flexible catheter with a small balloon is placed in the rectum. Pressure sensors measure the strength of the anal sphincter muscles and the reflexes necessary for proper defecation. The balloon can be inflated to test rectal sensation and the ability to expel contents, which helps diagnose pelvic floor dysfunction.
Preparing for the Study and Understanding the Findings
Accurate results from a motility study depend on careful patient preparation. A common requirement is fasting for a specific number of hours before the procedure, typically overnight, to ensure the digestive tract is empty. Patients are routinely instructed to stop taking medications that affect GI muscle activity several days before the test. These medications include prokinetic agents (which stimulate movement), narcotics, and antispasmodics (which slow movement). For patients with diabetes, blood sugar control is monitored, as high glucose levels can independently slow gastric emptying and skew results.
Once the study is complete, the findings provide the physician with objective data on the speed and strength of muscle contractions. The results are compared against established normal ranges to identify specific patterns of dysfunction, such as weak or uncoordinated muscle action. This information is used to tailor a treatment plan. Treatment may involve specialized medications, dietary adjustments, or physical therapy, addressing the precise mechanical problem.