['Nissen-Collis gastroplasty (NCG) is an effective treatment for short esophagus, but it sometimes is associated with abnormal postoperative esophageal acid exposure. This study was designed to test the hypothesis that NCG prevents gastric reflux and that pathologic distal esophagus acid exposure is due to prolonged acid clearance in the "neoesophagus."', 'The study enrolled 11 normal healthy subjects (ten patients status post--laparoscopic Nissen fundoplication and nine patients status post-NCG). All the participants were age and gender matched, and all were studied via manometry, acid-clearance test, and 24-h pH analysis. The clearance test was performed according to an established protocol. A 15-ml acid bolus (pH 1.2) was rapidly infused (×4) using a nasogastric tube 15 cm proximal to the lower esophageal sphincter, followed by dry swallows every 30 s until the esophageal pH rose above 4.', 'All the subjects had normal esophageal peristalsis and distal amplitudes. The acid-clearance time was significantly higher with NCG (P < 0.001 vs Nissen and normal subjects). Pathologic esophageal acid exposure occurred in one of ten Nissen patients (10 %) and in two of nine NCG patients (22 %) (nonsignificant difference [NS]). The median distal esophageal acid exposure time during the 24-h pH study was similar in the two groups (NCG, 1.2 %; Nissen, 2.5 %; NS).'] Is esophageal acid-clearance physiology altered after Nissen-Collis gastroplasty?