Confirmatory Diagnosis of Achalasia
A 45-year-old woman has 18 months of dysphagia to liquids and solids, retrosternal pain on swallowing and regurgitation of undigested food. Barium swallow shows a dilated esophagus tapering to a smooth beak at the cardia. Upper endoscopy shows no mucosal lesion or mass. Which of the following investigations has the highest diagnostic value?
- A.Esophageal high resolution manometryCorrect
- B.Ambulatory 24 hour esophageal pH monitoring
- C.Repeat barium swallow
- D.Contrast enhanced CT of the chest
Explanation
Dysphagia to liquids as well as solids, retrosternal pain and regurgitation of undigested food form a triad highly characteristic of achalasia. Achalasia results from degeneration of inhibitory ganglion cells in the myenteric plexus, producing two functional defects: failure of the lower esophageal sphincter to relax on swallowing, and loss of peristalsis in the esophageal body. High resolution manometry is the gold standard because it is the only test that measures both defects directly, quantifying the integrated relaxation pressure and the pattern of contractility. It also subtypes achalasia into types I, II and III under the Chicago Classification, which predicts response to pneumatic dilatation, Heller myotomy and peroral endoscopic myotomy and therefore changes management. The barium swallow has already suggested the diagnosis with a bird beak taper, but it is an anatomical study and repeating it adds nothing. Endoscopy has already served its purpose by excluding a tumour at the cardia causing pseudoachalasia. CT of the chest is used to exclude extrinsic compression or malignancy, not to characterise a motor disorder. Ambulatory pH monitoring quantifies acid reflux and is misleading in achalasia, where retained fermenting food can generate a falsely abnormal acid exposure.
Why each option
- A.
- Correct. High resolution manometry is the gold standard, directly demonstrating impaired lower esophageal sphincter relaxation and absent peristalsis, and it subtypes the disease.
- B.
- Ambulatory pH monitoring assesses acid reflux and can be falsely abnormal in achalasia because of fermentation of retained food.
- C.
- The barium swallow has already been done and is diagnostic of a pattern, not of the underlying motor physiology. Repeating it adds no information.
- D.
- CT excludes extrinsic compression or malignancy but cannot measure sphincter relaxation or peristalsis.
Reference: Chicago Classification version 4.0, Neurogastroenterol Motil 2021; ACG Clinical Guidelines: Achalasia, 2020
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