Background Laparoscopic Nissen fundoplication (LNF) is the most frequently performed operation for gastro-oesophageal reflux disease (GORD). However, 12% of the patients have persistent reflux symptoms and 19% develop gas-related symptoms after LNF. Weakly acidic reflux and inability to belch have been alleged to cause these symptoms, respectively. The effect of LNF on weakly acidic reflux and (supra) gastric belching was evaluated.

Methods In 31 patients upper gastrointestinal endoscopy, stationary oesophageal manometry and 24-h impedance–pH monitoring off acid secretion inhibiting drugs was performed before and 6 months after primary LNF for GORD that was refractory to proton pump inhibitors. Patients filled out validated questionnaires on GERD-HRQoL before and 3, 6 and 12 months after surgery.

Results LNF reduced reflux symptoms (18.6→1.6; p=0.015). The procedure drastically reduced the incidence (number per 24 h) of acid (76.0→1.6; p<0.001) and weakly acidic (13.6→5.7; p=0.001) as well as liquid (53.4→5.4; p<0.001) and mixed reflux episodes (36.3→1.9; p<0.001). In contrast, gas reflux was reduced to lesser extent (35.6→25.7; p=0.022). Proximal, mid-oesophageal and distal reflux were reduced to a similar extent. Persistent GORD symptoms were neither preceded by acid nor by weakly acidic reflux. The number of air swallows did not change, but the number of gastric belches (GBs) was greatly reduced (68.5→23.9; p<0.001). Twenty-three patients had supragastric belches (SGBs), both before and after surgery, whereas eight patients had no SGBs at all. The majority of SGBs were not reflux associated and the frequency was greatly increased after LNF (20.8→46.0; p=0.036). Reflux-associated SGBs were abolished after surgery (14.0→0.4; p<0.001).

Conclusions LNF similarly controls acid and weakly acidic reflux, but gas reflux is reduced to lesser extent. Persistent reflux symptoms are neither caused by acid nor by weakly acidic reflux. LNF alters the belching pattern by reducing GBs (air venting from stomach) and increasing SGBs (no air venting from stomach). This explains the increase in belching experienced by some patients after LNF, despite the reduction in gastric belching. It can be hypothesised that the reduction in GBs after LNF incites patients to increase SGBs in a futile attempt to vent air from the stomach.