What is the best test to confirm achalasia in an adult patient with symptoms of dysphagia?

Best Test for Confirming Achalasia

High-resolution esophageal manometry (HRM) is the definitive diagnostic test for achalasia, with 98% sensitivity and 96% specificity, and should be performed after endoscopy has excluded structural causes. 1

Diagnostic Algorithm

Step 1: Initial Evaluation - Endoscopy First

• Perform upper endoscopy with esophageal biopsies before manometry to exclude structural abnormalities (strictures, tumors) and mucosal disorders (eosinophilic esophagitis) that can mimic achalasia 2, 3
• This sequence is critical because structural lesions are more common than achalasia and must be ruled out first 2

Step 2: Definitive Diagnosis - High-Resolution Manometry

• HRM is superior to standard manometry in terms of reproducibility, speed of performance, and ease of interpretation 2
• HRM diagnoses achalasia by demonstrating:
  • Elevated integrated relaxation pressure (IRP) >15 mm Hg (Manoscan) or >25 mm Hg (Unisensor), indicating impaired lower esophageal sphincter relaxation 1
  • Absent or abnormal esophageal peristalsis 1
• HRM provides critical achalasia subtype information (Types I, II, III) that predicts treatment outcomes, with Type II responding best to therapy and Type III having the poorest response 1, 3

Step 3: Complementary Study - Barium Esophagram

• A biphasic barium esophagram is highly valuable as a complementary study because it can simultaneously detect both structural abnormalities and functional motility disorders 3, 4
• Barium studies have 80-89% sensitivity and 79-91% specificity for diagnosing achalasia compared to manometry 3, 4
• Important caveat: Some achalasia patients (33% in one study) show complete LES relaxation on manometry despite characteristic radiographic findings, meaning barium studies may occasionally reveal dysmotility not detected on manometry 5
• Esophagography alone has limited diagnostic yield, with only 78.3% sensitivity, missing approximately 22% of achalasia cases 6

Why Manometry is Essential

• Manometry is pathognomonic for achalasia even in early clinical stages when radiographic findings may be equivocal 7
• Missing achalasia before antireflux surgery is catastrophic, as performing fundoplication on an achalasia patient leads to severe complications 2, 1
• Manometry must be performed before any antireflux surgery if there is any question of an alternative diagnosis 2

Common Pitfalls to Avoid

• Do not rely solely on esophagography for diagnosis - approximately 22% of achalasia cases will be missed, particularly early-stage disease 6
• Do not use manometry as the initial test - always perform endoscopy first to exclude the more common structural causes 2
• Recognize that complete LES relaxation on manometry does not exclude achalasia - if radiographic findings are typical, proceed with treatment even with normal manometry 5
• Use manufacturer-specific and catheter-specific normal values, as IRP thresholds differ significantly between systems 1