Correct Answer: C. Manometry
Manometry is the gold-standard confirmatory investigation for esophageal motility disorders, particularly achalasia. The clinical presentation (progressive dysphagia to solids and liquids, regurgitation of undigested food, chest pain) combined with a characteristic radiological finding of a dilated esophagus with a smooth, tapered "bird's beak" appearance at the gastroesophageal junction on barium swallow strongly suggests achalasia. However, barium swallow is diagnostic only in advanced cases; manometry is the definitive confirmatory test. High-resolution esophageal manometry demonstrates the pathognomonic findings: elevated lower esophageal sphincter (LES) pressure (>45 mmHg), incomplete LES relaxation (<75% relaxation), and absent primary peristalsis in the esophageal body. These findings confirm the diagnosis and exclude pseudoachalasia (malignancy, scleroderma). In Indian clinical practice, manometry is essential before initiating treatment (botulinum toxin, pneumatic dilation, or myotomy) as per standard gastroenterology protocols. The test is non-invasive, reproducible, and provides objective measurement of esophageal function, making it superior to endoscopy for functional assessment.
Why the other options are wrong
A. Barium swallow study — While barium swallow is the initial imaging modality and may show the characteristic 'bird's beak' sign and dilated esophagus in achalasia, it is diagnostic (not confirmatory) and does NOT measure esophageal motility or LES pressure. It cannot differentiate true achalasia from pseudoachalasia or other motility disorders. Manometry is required to confirm the functional defect and guide treatment decisions. B. Upper GI Endoscopy — Endoscopy is useful to exclude mechanical obstruction (malignancy, stricture) and rule out pseudoachalasia, but it is NOT confirmatory for achalasia itself. It cannot assess esophageal motility or measure LES pressure. The endoscopic finding of a tight LES with resistance to passage is suggestive but not diagnostic. Manometry provides objective functional confirmation. D. pH monitoring — pH monitoring (24-hour ambulatory pH study) is used to diagnose gastroesophageal reflux disease (GERD), not achalasia. It measures acid exposure in the esophagus and is irrelevant for confirming motility disorders. This is a distractor for students confusing esophageal symptoms; achalasia presents with dysphagia and regurgitation, not heartburn.
High-Yield Facts
- Manometry is the gold-standard confirmatory test for achalasia, demonstrating elevated LES pressure (>45 mmHg) and incomplete relaxation.
- Barium swallow shows 'bird's beak' sign and dilated esophagus but is diagnostic imaging, not functional confirmation.
- Pseudoachalasia (malignancy, scleroderma) must be excluded by manometry before treatment; endoscopy rules out mechanical causes.
- High-resolution manometry (HRM) is superior to conventional manometry and is the preferred modality in tertiary centers across India.
- Absent primary peristalsis in the esophageal body on manometry is pathognomonic for achalasia and differentiates it from other motility disorders.
Mnemonics
MANE for Achalasia Workup Manometry (confirmatory) → Analysis of motility → No peristalsis → Excludes pseudoachalasia. Use this to remember that manometry is the final confirmatory step after imaging suggests achalasia. BBE Rule Barium = imaging, Bird's beak = suggestive, Endoscopy = exclusion of mechanical causes. Manometry = confirmation. Helps students remember the sequence: imaging → exclusion → confirmation.
NBE Trap
NBE pairs barium swallow findings with the question to lure students into selecting imaging as the 'confirmatory' test. The trap is conflating diagnostic imaging with functional confirmation—barium swallow is diagnostic but manometry is confirmatory for the underlying motility defect.
Clinical Pearl
In Indian tertiary care, a patient presenting with progressive dysphagia and a barium swallow showing dilated esophagus with bird's beak is presumed achalasia, but manometry is mandatory before pneumatic dilation or laparoscopic myotomy to confirm the diagnosis and rule out pseudoachalasia (which would require oncology referral instead).
_Reference: Harrison Ch. 286 (Disorders of Esophageal Motility); Robbins Ch. 17 (GI Pathology); KD Tripathi Ch. 40 (Esophageal Disorders)_