For Surgeons
Sleeve gastrectomy, Roux-en-Y bypass, and partial or total gastrectomy each remove or bypass a portion of the oxyntic mucosa, the parietal cell mass that produces hydrochloric acid and intrinsic factor. Fundoplication leaves that mass intact but changes the mechanics around it.
How much secretory capacity a given patient retains after a given operation is rarely measured. It is inferred from the procedure, and inference varies widely between patients. The Heidelberg pH Capsule System reports intragastric pH in real time and quantifies the response to a standardized challenge.
A direct measurement, not an assumption.
Sample Tracing
The Underlying Physiology
Parietal cells are concentrated in the oxyntic mucosa of the fundus and body. They secrete hydrochloric acid and intrinsic factor. The antrum contains gastrin-producing G cells that drive that secretion, but no parietal cells of its own.
Every foregut and bariatric operation intersects this map differently. A sleeve removes much of the greater curvature and fundus. A Roux-en-Y pouch is fashioned from the cardia, where parietal cell density is lowest, and excludes the remnant from the food stream. An antrectomy removes the gastrin drive rather than the acid-producing cells themselves. A total gastrectomy removes both.
Downstream, the same physiology governs B12 liberation from dietary protein, the reduction of ferric to ferrous iron, the dissolution of calcium carbonate, the absorption of weak-base drugs, and the acid barrier that limits bacterial colonization of the small bowel.
Oxyntic Mucosa Remaining · Schematic
By Procedure
Sleeve Gastrectomy
Resection of the greater curvature removes a large share of fundic and body mucosa. The extent varies with bougie size and the distance from the pylorus, so the residual secretory capacity varies too. De novo reflux after sleeve is common and mechanical in origin, which raises the question of whether the symptom is acid-mediated at all in a stomach with reduced parietal cell mass.
Roux-en-Y Gastric Bypass
A small proximal pouch is fashioned from tissue with low parietal cell density. The remnant stomach retains its secretory mass but is excluded from the food stream and out of reach of standard endoscopy. Marginal ulceration at the gastrojejunostomy remains a recognized late complication, and pouch acid is one of several implicated mechanisms alongside smoking, NSAIDs, ischemia and H. pylori.
Fundoplication
A wrap is mechanical. Parietal cell mass is unchanged and secretory capacity is unchanged with it. The pre-operative question is therefore not how much acid remains but whether the presenting symptom is acid-mediated in the first place, given that outcomes are less favorable in reflux hypersensitivity and functional heartburn. Gastric pH characterizes the secretory environment; it does not measure esophageal acid exposure and is not a substitute for pH-impedance monitoring.
Partial & Total Gastrectomy
A distal resection removes the antral gastrin drive while leaving oxyntic mucosa in place, which is reduced stimulation rather than reduced capacity. A total gastrectomy removes the parietal cell population outright, producing achlorhydria and an absolute, lifelong requirement for parenteral B12. Between those two poles sits a range of partial resections where the residual state is genuinely uncertain without measurement.
Applications
Pre-operative
A documented pre-operative secretory profile gives you something to compare against when a patient returns at six months with symptoms. Without it, post-operative findings have no reference point.
Post-operative Symptoms
Burning, epigastric pain and regurgitation after foregut surgery may be acid-mediated, mechanical, biliary, or functional. Measuring the acid environment directly removes one branch of the differential rather than assuming it.
Acid Suppression Review
Post-operative acid suppression is frequently started for prophylaxis and then continued indefinitely without anyone establishing whether the patient still produces acid. A direct measurement informs that conversation. Any change to therapy remains a clinical decision for the treating team.
Deficiency & SIBO Workup
B12, iron and calcium handling all depend on gastric acid, and hypochlorhydria removes a barrier to small bowel bacterial colonization. Where deficiencies persist despite supplementation, the acid state is a measurable variable in the workup.
Post-bariatric gastric pH rises 3 to 4 units. Porat / Azran et al., 2021.
How It Works
01
Calibrate
Two-point calibration at pH 1.0 and pH 7.0 against reference buffers.
02
Administer
The patient swallows the tethered capsule. Record fasting baseline pH, then deliver sequential sodium bicarbonate challenges.
03
Measure
Time the return to baseline acidity after each challenge. Reacidification interval, pattern, and how strongly the stomach restores its acidity, read directly from the tracing.
Altered Anatomy
The capsule is tethered, positioned under the operator's control and withdrawn at the end of the study rather than passed. In a reconstructed stomach it reports the pH of the compartment it occupies: the sleeve remnant, or the gastric pouch in a Roux-en-Y, which is the compartment the patient actually uses. Suitability in any individual post-surgical patient, including the presence of strictures, revisional anatomy or other contraindications, remains a matter for the operating surgeon's judgement.
Engagement
System and capsule supply for bariatric and foregut programs, protocol and calibration support, and methodological input on interpreting tracings in reconstructed anatomy.
In-office Testing
The study is performed in the office by the practice, with results available at the point of care.
Protocol Support
Guidance on baseline and challenge protocol in pre-operative and post-operative settings.
Interpretation
Input on reading tracings where the anatomy is reconstructed and the reference range is not the intact stomach.
Research Collaboration
For centers building a series in post-surgical secretory outcomes, we support study design and supply.
Get in Touch
Tell us what you operate on and what you are trying to answer. We will follow up directly.
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Or email us directly at info@heidelbergmed.com
Indicated for use by qualified healthcare professionals. CAUTION: Federal Law (USA) restricts these devices to sale by or on the order of a physician.