Achalasia is diagnosed primarily through a pressure-sensing test called high-resolution manometry, which measures how well your esophagus squeezes and whether the valve at its bottom opens properly when you swallow. Because achalasia is uncommon and its symptoms overlap heavily with acid reflux, most people wait years before getting the right diagnosis. The majority of patients are initially misdiagnosed with GERD or asthma, causing delays of up to five years.
Understanding the full diagnostic process can help you know what to expect and advocate for the right tests if your symptoms aren’t improving with standard reflux treatment.
Why Achalasia Is Often Missed at First
The hallmark symptoms of achalasia, difficulty swallowing, chest pressure, and regurgitation, look a lot like acid reflux. Many people spend months or years on acid-suppressing medications before anyone considers a different diagnosis. The American College of Gastroenterology now recommends that patients initially suspected of having GERD who don’t respond to acid-suppressive therapy should be evaluated for achalasia.
This matters because the longer achalasia goes untreated, the more the esophagus stretches and weakens. Getting to the right diagnosis sooner leads to better treatment outcomes.
Manometry: The Definitive Test
High-resolution manometry is the gold standard for confirming achalasia. During this test, a thin, flexible catheter is passed through your nose and down into your esophagus. The catheter contains dozens of tiny pressure sensors along its length. You’ll be asked to take 10 sips of water while the sensors record how your esophageal muscles contract and, critically, whether the lower esophageal sphincter (the valve between your esophagus and stomach) relaxes when it should.
The key measurement is called integrated relaxation pressure, or IRP. This captures how well that lower valve opens during each swallow. A general threshold for abnormal IRP is 15 mm Hg, though some achalasia patients fall in a borderline range of 10 to 15 mm Hg. Your final result is the median IRP across all 10 swallows.
Manometry also classifies achalasia into three subtypes, which matters because it influences which treatment works best:
- Type I (classic): No detectable muscle contractions in the esophagus and no pressure buildup during swallows. The esophagus is essentially silent.
- Type II: No normal contractions, but the esophagus builds up pressure uniformly during swallows, like a pressurized tube. This is the most common subtype and tends to respond best to treatment.
- Type III (spastic): Instead of normal coordinated squeezing, the esophagus produces premature, spastic contractions. This subtype can be harder to treat.
These subtypes are defined by the Chicago Classification system, which is the international standard gastroenterologists use to interpret manometry results. The latest version also added an “inconclusive diagnosis” category for cases that don’t fit neatly into one subtype.
Preparing for Manometry
You’ll need to stop eating and drinking at midnight the night before. Certain medications must be held on the day of the test because they can affect esophageal muscle activity. These include opioid pain medications, sedatives and anxiety medications, and drugs that speed up gut motility. Other routine medications can typically be taken up to two hours before the procedure with a small sip of water. If you take diabetes medications, check with your doctor about dosing adjustments.
The test itself takes about 20 to 30 minutes. The catheter insertion can be uncomfortable, but it isn’t painful, and no sedation is needed. You’ll be awake and sitting upright for most of it.
Barium Swallow: Seeing the Problem
A barium esophagram gives your doctor a visual picture of how your esophagus empties. You drink a chalky barium liquid while standing in front of an X-ray machine, and images are taken as the barium moves (or fails to move) through your esophagus.
The classic finding is a “bird’s beak” appearance: the esophagus tapers to a sharp, narrow point at the lower sphincter, with a column of barium sitting above it because it can’t get through. You may also see a visibly widened esophagus, a sign that the organ has stretched over time from chronic obstruction.
A timed version of this test is especially useful. You drink about 8 ounces of barium, and images are taken at one and five minutes. If the barium column is still taller than 5 cm after one minute, that’s 94% sensitive for untreated achalasia. A column taller than 2 cm at the five-minute mark is both 85% sensitive and 86% specific, meaning it reliably distinguishes achalasia from other conditions that can mimic it. The timed barium swallow is also valuable after treatment, since a greater than 50% improvement in column height correlates with good symptom relief.
Upper Endoscopy: Ruling Out Other Causes
An upper endoscopy (where a camera on a flexible tube is passed down your throat) is a standard part of the workup, but not because it’s great at confirming achalasia. Its main job is ruling out conditions that mimic achalasia, particularly esophageal cancer, which can compress the lower sphincter and produce identical symptoms. This cancer-related lookalike is called pseudoachalasia, and distinguishing it from true achalasia is essential. Endoscopy also helps exclude esophageal webs and a condition called eosinophilic esophagitis.
When endoscopy does show signs of achalasia, the most common findings are a widened esophageal opening and food or liquid sitting in the esophagus that should have cleared. You might also see resistance when the scope passes through the lower sphincter, though the scope can still get through (unlike a true physical blockage). However, only about half of achalasia patients show these characteristic features on endoscopy, so a normal-looking endoscopy does not rule achalasia out. That’s why manometry remains the definitive test.
Researchers have identified some subtler endoscopic clues in recent years: a fine “pinstripe pattern” of tiny wrinkles on the esophageal lining, rosette-like folds in the lower esophagus, and a “champagne glass sign” visible when the camera looks back at the junction from below. These patterns are increasingly recognized, but they supplement rather than replace manometry.
When Results Are Unclear
Sometimes manometry and the barium swallow don’t tell the same story. A patient might have borderline pressure readings on manometry but a clearly abnormal barium swallow, or vice versa. In these cases, a newer tool called EndoFLIP can help. This device is a small balloon-tipped catheter placed during endoscopy that measures how easily the lower sphincter stretches open. It provides a different angle on sphincter function and is particularly useful when the standard tests conflict.
Borderline IRP values between 10 and 15 mm Hg also create diagnostic gray areas. In these situations, doctors look at the full picture: the manometry pattern, imaging findings, symptom history, and sometimes EndoFLIP results to reach a conclusion.
The Typical Diagnostic Path
In practice, most people don’t walk into a doctor’s office and immediately get manometry. The usual sequence starts with an upper endoscopy to evaluate swallowing difficulty and rule out structural problems or cancer. If the endoscopy is normal or suggests achalasia, a barium swallow and manometry follow. Manometry confirms the diagnosis and identifies the subtype, while the timed barium swallow provides a baseline measurement of how poorly the esophagus empties, which becomes useful for tracking treatment success later.
If you’ve been treated for reflux without improvement, particularly if you have trouble swallowing both solids and liquids, regurgitation of undigested food, or unexplained weight loss, asking specifically about achalasia testing can help avoid further diagnostic delays.