How to interpret high-resolution manometry in achalasia

High-resolution manometry (HRM) is the key physiological test for confirming achalasia and separating it from other causes of dysphagia. Unlike conventional manometry, HRM displays pressure activity across the entire esophagus as a color topography plot, allowing clinicians to evaluate the lower esophageal sphincter (LES), esophageal body, and the coordination of swallowing in one study.

Interpretation should follow a consistent sequence rather than relying on a single pressure value. The clinician first confirms that the catheter has captured the upper and lower sphincters, then assesses the integrated relaxation pressure (IRP), peristalsis, and the presence of abnormal pressurization.

The findings should always be matched with symptoms, endoscopy, and timed barium esophagram results. This is especially important when anatomy, prior treatment, opioid exposure, or an obstructing lesion could produce manometric patterns that resemble achalasia.

Start with technical quality

A reliable study begins with correct catheter placement and adequate recording. The pressure sensors should identify the upper esophageal sphincter, esophageal body, and LES or esophagogastric junction (EGJ). The patient typically performs a series of ten 5-mL water swallows in a supine or standardized position, followed by additional maneuvers when the initial results are inconclusive.

Before classifying the disorder, check whether the baseline EGJ pressure is plausible and whether respiratory landmarks are visible. A hiatal hernia, catheter looping, poor cooperation, or anatomic distortion can affect measurements. Incomplete visualization of the LES may make an apparently normal or elevated IRP unreliable.

Assess EGJ relaxation and peristalsis

The IRP estimates how well the LES relaxes during swallowing. An elevated IRP suggests impaired EGJ relaxation, but the threshold depends on the catheter system, patient position, and laboratory protocol. Values should therefore be interpreted against the manufacturer’s normal range rather than an isolated universal cutoff.

Next, review the ten swallows for contraction pattern. In untreated achalasia, normal sequential peristalsis is absent. The combination of impaired relaxation and absent peristalsis supports the diagnosis, while preserved peristalsis points toward an alternative motility disorder or an equivocal form of EGJ outflow obstruction.

Recognize the achalasia subtypes

The Chicago Classification divides achalasia into three clinically useful manometric patterns. Type I has impaired EGJ relaxation with absent contractility and little or no pressurization in the esophageal body. It often reflects advanced loss of esophageal muscle function.

Type II also shows impaired relaxation and absent normal peristalsis, but at least 20% of swallows generate panesophageal pressurization. The entire esophageal body pressurizes simultaneously, indicating retained muscular response to a closed outlet.

Type III, or spastic achalasia, combines impaired EGJ relaxation with premature or spastic contractions in at least 20% of swallows. This pattern can be associated with more prominent chest pain and may influence treatment selection because the spastic segment can extend well above the LES.

Distinguish mimics and borderline findings

An elevated IRP with preserved peristalsis is not automatically achalasia. It may indicate EGJ outflow obstruction, opioid-related dysfunction, a hiatal hernia, or mechanical narrowing from a tumor or inflammatory stricture. Endoscopy is essential when symptoms are new, progressive, or accompanied by weight loss, because pseudoachalasia can mimic the manometric pattern.

Borderline studies may benefit from upright swallows, a rapid drink challenge, or a solid test meal when available. A timed barium esophagram can show whether contrast retention and delayed emptying support clinically significant obstruction. These complementary tests are particularly useful when symptoms and HRM findings do not align.

Use provocative tests thoughtfully

Provocative maneuvers can reveal abnormalities that standard water swallows miss. During a rapid drink challenge, failure of the EGJ to relax or a markedly elevated pressurization response may reinforce the presence of outflow obstruction. Multiple rapid swallows can assess contractile reserve, although the result must be interpreted in the context of absent peristalsis and prior therapy.

Post-treatment HRM requires extra caution. Pneumatic dilation, Heller myotomy, and peroral endoscopic myotomy can lower the IRP without restoring normal peristalsis. A persistent abnormal contraction pattern does not necessarily mean treatment failure; symptom relief and esophageal emptying remain central to clinical assessment.

Apply the result to patient care

Manometry confirms physiology, but it does not determine management by itself. Type I and type II disease may respond well to pneumatic dilation, laparoscopic myotomy with fundoplication, or peroral endoscopic myotomy, while type III disease often requires attention to the length of the spastic segment. Treatment discussions should incorporate age, fitness, anatomy, reflux risk, local expertise, and patient preference.

Symptoms can also overlap with other esophageal disorders. For example, dietary triggers and food avoidance in eosinophilic esophagitis require a different diagnostic pathway, as outlined in these dietary management strategies. HRM should be used to answer a specific motility question, not as a substitute for endoscopic evaluation and mucosal biopsy when inflammation is suspected.

Practical interpretation habits

• Confirm catheter position, study quality, and the laboratory’s normal IRP threshold.
• Evaluate EGJ relaxation before analyzing the esophageal contraction pattern.
• Require absent normal peristalsis when diagnosing classic achalasia.
• Use panesophageal pressurization and premature contractions to distinguish types II and III.
• Investigate mechanical obstruction and pseudoachalasia when clinical findings are atypical.

A disciplined reading of the pressure topography helps turn a complex HRM study into a clinically meaningful diagnosis. Review the tracing alongside endoscopy, contrast imaging, and the patient’s symptom history, then document the manometric subtype and any uncertainty clearly for the multidisciplinary treatment team.