Gold Standard for Diagnosis of GORD

The true 'gold standard' investigation for diagnosing Gastro-Oesophageal Reflux Disease (GORD) is 24-hour pH recording (ambulatory oesophageal pH monitoring). This is because GORD is fundamentally defined by pathological, excessive reflux of gastric acid into the oesophagus — and 24-hour pH monitoring is the only test that directly and objectively quantifies acid exposure over a full day, correlating symptoms with actual reflux episodes in real time.

Why 24-hour pH Recording is the Gold Standard:

• It directly measures the frequency, duration, and severity of acid reflux episodes by recording intraluminal oesophageal pH over 24 hours.
• It calculates the DeMeester score, the objective diagnostic criterion used to confirm pathological reflux.
• It allows correlation between a patient's symptoms (heartburn, regurgitation) and actual episodes of acid reflux, which is essential in patients with normal endoscopy findings (non-erosive reflux disease).
• It is considered the most sensitive and specific test for confirming the diagnosis of GORD, especially prior to anti-reflux surgery.

Why the Other Options are Incorrect:

• Upper GI endoscopy: This is extremely useful and is the first-line investigation for detecting complications of GORD such as oesophagitis, strictures, and Barrett's oesophagus, and for excluding malignancy. However, up to 50-70% of patients with true GORD have a normal-appearing oesophagus on endoscopy (non-erosive reflux disease), so a normal endoscopy does not rule out GORD. Endoscopy assesses mucosal damage, not the presence or quantity of reflux itself, so it cannot serve as the definitive diagnostic gold standard.
• Barium meal follow through: This is a screening/anatomical test that can show a hiatus hernia or gross reflux of contrast, but it has poor sensitivity and specificity for GORD and is not used to confirm the diagnosis.
• CT scan: CT has no established role in the routine diagnosis of GORD; it is reserved for evaluating suspected complications, malignancy, or alternative diagnoses, not for confirming reflux disease.

Therefore, the correct answer is 24-hour pH recording, as it is the only investigation that objectively confirms and quantifies pathological acid reflux, making it the true diagnostic gold standard for GORD.