Reproducibility of oesophageal transit studies: several 'single swallows' must be performed.

The 'single swallow' technique for the isotopic investigation of oesophageal function has been widely accepted. In our experience the results obtained when several consecutive 'single swallow' tests are performed show considerable variation. Although one or two swallows may be enough to diagnose abnormality, the exclusion of a motility disorder requires more, preferably six consecutive swallows.