A manometry test measures pressure inside parts of your digestive tract to find out how well the muscles there are working. The most common types are esophageal manometry, which checks the swallowing muscles in your food pipe, and anorectal manometry, which evaluates the muscles involved in bowel movements. The test uses a thin, flexible tube with pressure sensors to detect whether muscles are squeezing too hard, too weakly, or out of sync with each other.
What Esophageal Manometry Measures
Your esophagus is a muscular tube that moves food from your throat to your stomach through coordinated waves of squeezing. At the top and bottom of the esophagus sit ring-shaped muscles called sphincters that open to let food through and close to keep stomach contents from coming back up. Esophageal manometry measures the pressure, speed, and pattern of contractions along the entire length of this tube, plus how well both sphincters open and close.
Doctors typically order this test when you have trouble swallowing, unexplained chest pain, or persistent acid reflux that hasn’t responded to medication. It’s also a required step before certain surgeries for reflux, because the surgeon needs to confirm your esophageal muscles are functioning well enough to handle the procedure. The results help identify specific motility disorders, including achalasia (where the lower sphincter fails to relax properly) and esophageal spasm.
What Anorectal Manometry Measures
Anorectal manometry focuses on the muscles and nerves at the end of the digestive tract. It measures the tone of the anal sphincter muscles, how well you sense fullness in the rectum, and whether your muscles coordinate properly when you bear down. The test often includes a balloon expulsion component: a small balloon is inflated inside the rectum and you’re asked to push it out. Most people can do this within a minute. If you can’t expel it within three minutes, it suggests a coordination problem called dyssynergic defecation.
The most common reasons for ordering this test are chronic constipation that hasn’t improved with laxatives and fecal incontinence that hasn’t responded to basic treatments. These results matter because they change the treatment approach. If the test reveals a coordination problem, pelvic floor biofeedback therapy is more effective than simply adding more laxatives. Anorectal manometry can also uncover underlying muscle dysfunction behind recurring hemorrhoids or chronic anal fissures.
How the Esophageal Test Works Step by Step
You’ll sit upright in a chair or on an exam table. A member of the care team sprays numbing medicine into your throat, applies numbing gel inside your nose, or both. Once the area is numb, a thin catheter is guided through one nostril, down the back of your throat, through the esophagus, and into the stomach. This is the most uncomfortable part, and it typically takes just a few seconds.
Once the catheter is in place, you lie on your back. You’ll first do a baseline swallow with nothing in your mouth, then take 10 small sips of water (about a teaspoon each), waiting at least 30 seconds between each sip. The sensors along the catheter record pressure changes with every swallow. Modern high-resolution catheters have up to 36 sensors spaced just 1 centimeter apart, creating a detailed color map of how pressure moves through your esophagus in real time. Older systems used only about 5 sensors spread far apart, which made it easier to miss problems. The healthcare team may gently move the catheter up or down during the test to get readings from different positions. When all the swallows are complete, the catheter is slowly withdrawn.
What to Expect: Duration, Sedation, and Discomfort
The esophageal version typically takes about 15 to 30 minutes once the catheter is in place. Anorectal manometry is similar in length. Neither test uses sedation by default. The readings depend on you being awake and able to swallow or bear down on command, so sedation has traditionally been avoided. That said, if you’ve tried the test before and couldn’t tolerate it, some centers now offer a sedation-assisted version using a short-acting anesthetic delivered through an IV, with an endoscope used to guide the catheter into position. Recent studies have found that this type of sedation has a negligible effect on the pressure readings, making it a viable option for patients who need it.
Without sedation, most people describe the nasal catheter as uncomfortable but not painful. The sensation of the tube in the back of the throat can trigger a gagging reflex, but the numbing medication helps reduce this. Breathing through your mouth and staying calm makes the insertion easier. Once the catheter is seated, the discomfort usually fades and the swallowing portion feels relatively routine.
Preparation Before the Test
You’ll need to stop eating and drinking for at least six hours before esophageal manometry so your stomach and esophagus are empty. Tell your doctor about all medications and supplements you take, because some can affect muscle function in the digestive tract. Your doctor will let you know which ones to pause and when to stop taking them before the procedure. Anorectal manometry preparation may include an enema beforehand, depending on your center’s protocol.
Risks and Side Effects
Manometry is one of the lowest-risk procedures in gastroenterology. No serious complications have been documented in safety studies. The most common complaint is mild soreness in the throat or nose lasting several hours afterward. In one survey, about 48% of patients reported this mild-to-moderate soreness, and the rest reported no discomfort at all. Minor nosebleeds and sinus irritation can occur from the catheter passing through the nasal passages. You can eat and return to normal activities immediately after the test.
How Results Are Interpreted
For esophageal manometry, your doctor evaluates the results using a standardized system called the Chicago Classification, now in its fourth version. This framework sorts findings into specific motility disorders based on pressure patterns. One key measurement is the lower esophageal sphincter’s relaxation pressure. In healthy people, this averages around 10 mmHg when lying down. Values above the normal range suggest the sphincter isn’t relaxing properly, which can point to conditions like achalasia. The color pressure maps generated by high-resolution systems let specialists see at a glance whether contractions are moving in the right direction, at the right speed, and with appropriate force.
For anorectal manometry, the focus is on resting sphincter tone (whether the muscle is too weak or too tight at baseline), squeeze pressure (how strongly you can voluntarily contract), rectal sensation thresholds (how much filling it takes before you feel the urge to go), and coordination patterns during simulated evacuation. Together, these measurements paint a detailed picture of what’s going wrong and point directly toward the right treatment.