Role of gastric acid in stomal ulcer after gastric bypass

The pathogenetic mechanisms of stomal ulcer after Roux-en-Y gastric bypass (RYGBP) are unclear. In order to study the role of gastric acid, we measured acidity in the proximal pouch using a pH-sensitive probe.

6 patients (5 females, mean age 45 years old at time of operation) with endoscopically confirmed stomal ulcer, were studied 2 to 6 years after RYGBP. All complained of epigastric pain that improved during proton pump inhibitor (PPI) therapy. Control subjects were 6 females (50 years old) who had had RYGBP at least 5 years earlier and denied symptoms of epigastric pain or heartburn. The pH-sensitive probe (Digitrapper-pH, Medtronic) was passed through the nose to the proximal pouch, guided by the calculated distance and pH response. The probe was left in place for 4 hours. The percentage of time with pH <4 was calculated.

The probe could be accurately positioned in the proximal pouch both in symptomatic patients and in controls as evidenced by the acid pH reaction. The proximal pouches of patients with stomal ulcer were significantly more exposed to acid compared to controls. The median percentage of time with pH <4 was 69% and 20% in the stomal ulcer and the control group, respectively (P<0.01). Barium follow-through excluded gastro-gastric fistula in stomal ulcer patients.

RYGBP patients with stomal ulcer have increased acid production in their proximal pouch in comparison with asymptomatic RYGBP patients. Gastric acid appears to have an important role in the pathogenesis of stomal ulcer.