Are 10 wet swallows an appropriate sample of esophageal motility? Yes and no

Background: Traditionally 10 wet swallows are used to assess esophageal motility. Given this relative small number of swallows concerns have been raised whether the abnormal findings based on 10 wet swallows would persist with another set of 10 wet swallows. Purpose: To evaluate whether 10 wet swallows during esophageal manometry is an adequate sampling of esophageal motility. Methods: Over a 4-month-period 100 consecutive patients (excluding patients with achalasia) were given 20 liquid (5 ml each) swallows. The standard manometry technique in our laboratory was performed using 10 wet swallows with pressure transducers placed 4 cm and 9 cm above the lower esophageal sphincter (LES). The diagnosis was based on the initial 10 swallows. The additional 10 swallows were blinded and separately analyzed, then compared with the initial swallows for each patient. Results: Of the 100 studies (64 women; mean age 5 1; range 21-85), 91 had a consistent diagnosis for both pairs of 10 swallows. The number of abnormal swallows (ineffective or simultaneous) differed between the 2 sets of 10 swallows in 9 patients, but, when the first 10 were analyzed vs. all 20 swallows only 2 patients had discordant diagnoses. There was an excellent agreement between the 1st and 2nd set of 10 swallows (kappa = 0.846) and between the first 10 and all 20 swallows (kappa = 0.965). Conclusions: Ten wet swallows are sufficient for making a manometric diagnosis, because additional swallows are likely to change the diagnosis in only 2% of patients.