Diagnostic testing of the oesophagus is indicated in three settings: (1) initial evaluation of a symptomatic patient; (2) in the preoperative patient to ensure successful surgery; and (3) in the postoperative patient with new or residual symptoms following surgery.

Diagnostically, the 24-h pH probe is considered to be the gold standard for documenting gastro-oesophageal reflux. A small-calibre catheter is passed through a nostril into the oesophagus, and is taped in place so that the distal tip of the probe is 5 cm above the upper margin of the lower oesophageal sphincter. The probe is attached to a recording box, which documents the oesophageal pH, confirming the number of episodes of acid reflux and the length of time needed to clear acid from the oesophagus with each reflux episode. The catheter remains in place for 24 h, while the patient is eating, sleeping, and performing his or her usual daily activities. During this time, the patient keeps a diary to correlate symptoms, meals, and sleep with the record of acid reflux generated by the pH probe. Established criteria are used to ascertain whether or not truly pathological reflux is present. Alternative or complementary studies are available, but none, other than the 24-h pH probe, provides an actual recording of reflux episodes in the ‘real life’ setting.

When use of a pH probe is not feasible, an oesophageal scintigraphy study offers a reasonable alternative. Scintigraphy entails ingesting an isotope-labelled liquid meal; radioactive counts are recorded over the oesophagus and stomach. A shortcoming of this method, however, is that it evaluates the patient over a very limited period in an artificial setting. Patients who primarily have reflux postprandially or nocturnally may, therefore, have a false-negative scintigraphic scan. From the patient's perspective, scintigraphy has the advantage of not needing to swallow a catheter. Often patients who will not tolerate a catheter are receptive to drinking the radioactively labelled liquid.

The traditional barium upper gastrointestinal series serves two purposes in gastro-oesophageal reflux. First, it can document the presence of reflux, and second, it can identify complications of reflux such as strictures, oesophagitis, oesophageal ulcers, or tumours (Table 1) 301. The limitation is the short length of time over which the patient is evaluated. To help compensate provocative manoeuvres may be attempted to elicit gastro-oesophageal reflux. Manual pressure over the stomach, increasing intra-abdominal pressure by straight-leg raising, or altering the patient's position from supine to prone (or prone to supine) all increase the likelihood of detecting reflux on a barium series. Unfortunately, neither the sensitivity nor the specificity can approach that of the 24-h pH probe in detecting reflux.

Upper gastrointestinal endoscopy does not provide a means of quantitating reflux directly, but does permit an assessment of mucosal injury that can result from reflux (Table 2) 302. Biopsies demonstrating basal cell hyperplasia or an excessive number of eosinophils strongly imply pathological gastro-oesophageal reflux.

Finally, there is the Bernstein acid perfusion test designed to determine whether a patient's symptoms result from exposing the oesophagus to acid. The Bernstein test entails infusing normal saline as a baseline, followed by 0.1 M hydrochloric acid into the mid or distal oesophagus in a single-blinded fashion such that the patient does not know he or she is receiving the acid. The acid is dripped in until the patient begins to experience heartburn or chest pain, or until 30 min have passed. Saline is then reinfused, to document resolution of symptoms, and for a few minutes as a ‘control’ before acid is reinfused as a second challenge. A test is considered positive if symptoms are elicited on two separate acid infusions. Although, this study does not document gastro-oesophageal reflux, it provides presumptive evidence that acid exposure of the oesophageal mucosa leads to the patient's symptoms.

Preoperatively, confirming the diagnostic suspicion of gastro-oesophageal reflux with a laboratory test such as a 24-h pH probe is valuable in reassuring both patient and surgeon that an antireflux procedure will indeed bring relief of symptoms. Additional studies to rule out confounding diagnoses, such as gastritis or cholelithiasis, may be warranted if the symptoms or diagnostic studies are equivocal.

Determining whether or not complications of refractory gastro-oesophageal reflux have occurred is a prudent preoperative measure, as such a finding might influence the surgical procedure selected. The evaluation should include an upper endoscopy with biopsies of the distal oesophagus to eliminate the possibility of Barrett's oesophagus with dysplasia. A barium swallow or an upper gastrointestinal endoscopy will also identify patients with reflux-induced strictures. A tight stricture or severe dysplasia in the setting of Barrett's oesophagus might indicate the need for resecting the involved segment of oesophagus, and thus, would alter the surgical plan.

Verifying normal peristalsis in the oesophageal body preoperatively is vital, as antireflux surgery essentially creates a barrier to the passage of material through the gastro-oesophageal junction. Inadequate strength of contractions or poorly co-ordinated contractions in the oesophageal body preoperatively, can leave the patient with dysphagia postoperatively. Advance knowledge of such a motility disorder might alter the decision to proceed with surgery. A barium swallow provides a gross estimate of oesophageal peristalsis. An oesophageal motility study, however, is a much more precise evaluation of peristalsis, and should be obtained preoperatively if possible.

An oesophageal motility study takes approximately 20 min and involves inserting a slender nasogastric catheter through which precise measurements are made. Two types of catheters are available: solid state, or water-perfused. Currently, manometry provides the most accurate measurements of the strength of contractions as well as the timing and co-ordination of peristaltic waves down the oesophagus. Specific criteria have been set in terms of the amplitudes, durations, and timing of contractions in the body of the oesophagus, as well as normal ranges for the resting tone, percentage relaxation, and timing of relaxation of the upper and lower oesophageal sphincters. These measurements are used to define the various oesophageal motility disorders. A preoperative motility study is also useful in determining the exact location of the lower oesophageal sphincter.

Patients who have undergone an antireflux procedure may present themselves with three primary categories of postoperative problems that relate to oesophageal function: (1) continuation of the original reflux symptoms, (2) the new onset of dysphagia, or (3) the inability to belch. In patients who have symptoms of continued reflux postoperatively, studies should be initiated to determine whether or not the surgery has truly failed. A barium swallow, specifically to document passage of both barium liquid and tablets through the oesophagus, is essential. If this is not revealing, a 24-h pH probe, as was suggested for before surgery, should be obtained. If significant reflux is present, another operation may be indicated.

Persistent dysphagia following antireflux surgery generally indicates either inadequate peristalsis in the body of the oesophagus, or too tight a wrap at the base of the oesophagus. A barium swallow is the best initial study, using barium in both liquid and tablet form to assess bolus progression through the oesophagus. An oesophageal motility study provides the most precise measurements of oesophageal peristalsis, as well as the resting tone and function of the distal oesophagus in the region of the surgical wrap. If peristalsis is inadequate or if the wrap is too tight, dilatation of the distal oesophagus (or in certain cases, a second operation) may be required.

The inability to belch after antireflux surgery (the ‘gas-bloat syndrome’) suggests that the distal oesophagus may have been wrapped too tightly. As with dysphagia in the postoperative setting, a barium swallow and possibly oesophageal manometry are indicated.

Nearly 100 per cent of patients with achalasia present with dysphagia. The evaluation of oesophageal dysphagia generally begins with a traditional barium swallow to differentiate motility disorders such as achalasia from anatomical disorders such as strictures or webs. The classic radiological findings in achalasia include a dilated oesophageal body with the absence of peristaltic contractions, and a tapering of the distal oesophagus known as a ‘bird's beak’ which represents the tightly contracted lower oesophageal sphincter. Retained food often is present in the oesophagus due to delayed oesophageal clearance (Fig. 1) 921. Achalasia can also be staged according to the findings on a barium oesophagram. In Stage 1 disease the oesophageal body has a maximal diameter of less than 4 cm. In Stage 2 disease the maximal diameter is 4 to 6 cm; in Stage 3 disease, the diameter is greater than 6 cm. In the more advanced cases, the oesophageal body may progress into a sigmoid configuration. The proximal oesophagus generally appears normal, as it is comprised of striated muscle, and, therefore, is not affected by the disease process.

Ideally, oesophageal manometry to confirm achalasia is carried out. Although there are variants, the classic manometric findings in achalasia are low amplitude, non-peristaltic contractions in the oesophageal body, with an elevated resting tone of the lower oesophageal sphincter. Typically, the lower oesophageal sphincter also does not relax appropriately in response to swallows.

When achalasia is suggested on a barium oesophagram, upper endoscopy is indicated. Typically, a dilated oesophagus, often filled with debris, is found on endoscopy. Retroflexion in the stomach to view the gastro-oesophageal junction is essential to eliminate the possibility of a gastric tumour in the cardia. The high-pressure lower oesophageal sphincter of achalasia does not obstruct the passage of an endoscope into the stomach. Difficulty passing an endoscope into the stomach may signify a more serious problem, such as a tumour in the gastric cardia. Finding a neoplasm would clearly alter the therapeutic approach.

Following surgery for achalasia, nearly 20 per cent of patients experience gastro-oesophageal reflux. Diagnostic testing is generally not necessary, but would include a barium swallow or 24-h pH probe to document the reflux if there were any question about the aetiology of the patient's symptoms. An upper gastrointestinal endoscopy may be warranted in certain individuals to assess the presence or extent of reflux-induced oesophagitis.

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