Gastrointestinal (GI) motility describes the coordinated muscular contractions (peristalsis) that propel food and liquid through the digestive tract, from the esophagus down to the rectum. This process is essential for digestion, nutrient absorption, and waste elimination. Gastrointestinal motility testing is a specialized diagnostic process designed to measure the speed, strength, and coordination of these contractions throughout various segments of the digestive system. By objectively quantifying how quickly and effectively the digestive organs are moving their contents, physicians can identify physiological abnormalities. Measuring motility provides a functional assessment when symptoms suggest a problem with muscle or nerve function rather than a structural disease.
Symptoms Requiring a Motility Assessment
A specialist typically orders motility testing when a patient experiences chronic, disruptive symptoms that have not been explained by standard diagnostic procedures like endoscopy or imaging scans. These initial tests are performed to rule out structural issues, such as tumors or ulcers. Once structural problems are excluded, the focus shifts to evaluating the function of the muscles and nerves controlling the digestive process.
Common reasons for testing include chronic, unexplained nausea and vomiting, which suggests delayed stomach emptying. Severe symptoms of gastroesophageal reflux disease (GERD) that do not improve with standard medication may also prompt an assessment of esophageal function. Difficulty or pain when swallowing (dysphagia) is another primary indication, pointing to potential issues with the coordinated movement of the esophagus.
Motility tests are also used for patients with persistent, severe bowel issues, including chronic constipation or chronic diarrhea. These symptoms may result from either excessively slow transit or uncoordinated muscle activity in the small or large intestine. The goal of the assessment is to determine the specific segment of the digestive tract where the impairment is occurring to guide targeted treatment.
Different Types of Motility Tests
Motility testing involves several specialized procedures, each targeting a different segment of the digestive tract to measure motor function.
Esophageal Testing
For the esophagus, Esophageal Manometry is the standard test, utilizing a thin, pressure-sensing catheter passed through the nose and into the esophagus. This device measures the strength and pattern of muscle contractions during swallowing. It also assesses the relaxation of the lower esophageal sphincter, the valve between the esophagus and the stomach.
Gastric Testing
To evaluate the stomach, the most common test is a Gastric Emptying Scintigraphy (GES). The patient consumes a meal, typically eggs, that has been tagged with a small amount of a radioactive isotope. A specialized camera then takes images over a period, often four hours, to track the rate at which the food leaves the stomach and enters the small intestine.
An alternative method is the Wireless Motility Capsule (SmartPill). This swallowable device measures pH, pressure, and temperature as it moves through the entire GI tract. The capsule transmits data to an external receiver and determines the time it takes for the stomach, small bowel, and colon to empty.
Small and Large Bowel Testing
Motility of the small bowel and colon can be assessed using the wireless capsule or Radiopaque Marker Studies. For marker studies, the patient swallows small, non-digestible markers visible on X-ray. A series of X-rays are taken over several days to track the markers’ progression through the colon.
In more complex cases, Antroduodenal Manometry involves placing a catheter with pressure sensors into the stomach and small intestine. This directly records muscle activity patterns in response to fasting and eating.
Anorectal Testing
The function of the muscles controlling defecation is assessed with Anorectal Manometry. This procedure uses a small, flexible catheter inserted into the rectum. It measures the pressure exerted by the anal sphincter muscles at rest and during squeezing. It also evaluates the sensitivity of the rectum and the coordination between the rectal and anal muscles necessary for a successful bowel movement.
Patient Preparation and Post-Test Care
Proper preparation is necessary before a motility test to ensure accurate measurements, as residual food or certain medications can interfere with the results. Most motility tests require the patient to fast, meaning no food or drink after midnight, or for a period of eight to twelve hours before the procedure. This fasting status is particularly important for manometry and gastric emptying studies.
Patients are instructed to temporarily stop certain medications that affect digestive muscle activity. This often includes promotility agents, antispasmodics, and some narcotic pain relievers, typically for 48 to 72 hours prior to the test. A healthcare provider provides specific instructions tailored to the individual patient and the test being performed.
Following the test, post-procedure care is minimal, and most patients can resume their normal activities and diet immediately. For tests involving a catheter, such as manometry, some temporary throat or nasal discomfort may be felt. If a wireless motility capsule was swallowed, the patient will pass the device naturally with a bowel movement, and no retrieval is necessary.
Diagnosing Conditions from Test Results
The data collected from motility tests is analyzed to identify patterns of muscle and nerve dysfunction, which directly translates into a specific diagnosis. Abnormal results are categorized as either excessively slow, excessively fast, or uncoordinated movement. For instance, a GES result showing that more than 10 percent of the meal remains in the stomach after four hours confirms a diagnosis of Gastroparesis, or delayed gastric emptying.
Esophageal Manometry may reveal a lack of peristaltic contractions or a failure of the lower esophageal sphincter to relax, the hallmark of Achalasia. In the lower GI tract, a marker study showing markers remaining in the colon for an extended time points to Slow Transit Constipation. Anorectal manometry can identify Dyssynergic Defecation, where the abdominal and pelvic floor muscles do not coordinate correctly during attempted defecation.
These objective findings guide targeted therapeutic interventions. For example, a diagnosis of Gastroparesis may lead to pharmacological treatment, while Achalasia often requires endoscopic or surgical intervention. The test results confirm the underlying physiological mechanism and allow for targeted treatment planning.