Our Advanced GI Physiology Testing Service
Our Advanced GI Physiology Testing Service

Our Advanced GI Physiology Testing Service

We are thrilled to unveil a series of exciting new initiatives at The Functional Gut Clinic that will significantly enhance our ability to provide the highest quality GI Physiology testing service for patients. We have expanded our portfolio of testing to introduce new services that allow us to objectively assess more aspects of GI function that will lead to an increased level of diagnostic sensitivity.

Expanded areas of interest:

Gastric Neuromuscular Function:

New therapeutic options such as G-POEM have contributed to a resurgence of interest in patients with symptoms of dyspepsia and gastroparesis. Whilst gastric emptying remains a useful test of gastric function, it does not tell us about the underlying mechanisms of the problem.

We have now added a liquid meal challenge whilst recording autonomic nerve function via Electrogastrography (EGG) to our list of available foregut tests. This enables us to objectively assess patients for gastric neuropathies, pyloric outflow obstruction, gastric dysrhythmias and reflux related gastric dysfunction so that therapeutic options can be better targeted.  This is a 45-minute non-invasive test that complements gastric emptying data.

Typical EGG response in a patient with pyloric outflow obstruction

In addition, if a more comprehensive assessment is required, we have also introduced Gastric Alimetry, which is a high resolution, multichannel body surface mapping EGG system which involves a prolonged 4.5-hour recording with baseline recording, followed by ingestion of a test meal and detailed symptom mapping.

A spectral analysis of EGG from a high-resolution electrode array in this case showing evidence of vagal nerve damage post anti-reflux surgery.

This data reveals sophisticated insights into the complex pathophysiology of gastric neuromuscular disorders and combined with multidisciplinary team discussions of results, represents a massive leap forward in foregut diagnostics.

The Throat Service: In collaboration with the world-renowned laryngologist, Professor Martin Birchall, we proudly introduce The Throat Service. Professor Birchall’s unparalleled expertise in throat disorders combines with our advanced technology. Together, we offer the highest standard of care for patients dealing with dysphonia, pharyngeal dysphagia, chronic cough, and more. Our comprehensive services encompass cutting-edge diagnostic tests and innovative treatments, enabling precise diagnosis and effective management of chronic throat symptoms.

High Resolution Pharyngeal Manometry-Impedance (P-HRM-I):

Leveraging our advanced high-resolution manometry software, we can now evaluate pharyngeal muscle pressures during swallowing with precision to diagnose patients with throat disorders. Along with access to the Swallow Gateway which enables us to provide quantifiable biomechanical metrics of the pharynx and upper oesophageal sphincter (UOS) in exquisite detail (see below), we will shortly have the capability to combine with video fluoroscopy for the most comprehensive assessment of swallowing function currently available.

P-HRM-I – (A) High resolution manometry analysis of a pharyngeal swallow, via swallow gateway, demonstrating normal pharyngeal contractility and UOS relaxation with (B) pressure-impedance plot illustrating successful bolus passage and UOS opening measure via impedance.

Laryngo-pharyngeal Reflux (LPR)

LPR remains an enigma, but our research has shown a relationship between weakly acidic nocturnal ‘reflux’ and dysbiosis. We can now provide objective evidence of these pharyngeal pH and impedance changes using various methodologies including specific LPR probes (which also can be useful in confirming presence of functioning inlet patches) and Restech which can detect pharyngeal Ph changes.

Pharyngeal pH and impedance showing weakly acidic and weakly ionic ‘reflux’ during the nocturnal period.

Pharyngeal pH showing weakly acidic ‘reflux’ with Restech during the nocturnal period.

New tests of Gut Function

More and more we are being asked by patients about aspects of gut function that are commonly raised on social media but are difficult to test for objectively. At The Functional Gut we have worked hard on developing new validated assays so that these questions can be addressed objectively.

Low stomach acid:

Testing for low stomach acid levels comprises two components, fasting gastric acid levels and gastric acid output following a test meal. This can be done (if requested) as part of the standard 24-hour Ph and Impedance protocol or as a stand-alone test (taking 1-hour) in clinic. The Gastric Acid Output Test can identify Achlorhydria due to conditions such as pernicious anaemia, atrophic gastritis and parietal cell autoimmunity.

The test can be adapted to assess sub-types of neuroendocrine tumour, vagal nerve damage, PPI efficacy and conditions such as Zollinger Ellison syndrome in conjunction with other clinical indicators.

Hydrogen Sulphide Breath Testing:

Hydrogen sulphide is a volatile gas with an ‘eggy’ smell and at increased levels can be pro -inflammatory and associated with increased abdominal pain and diarrhoea. We have developed a new breath test to detect hydrogen sulphide in breath which previously was not possible (often resulting in false negative breath tests or “flatline” results).

“Flatline” result seen on a hydrogen and methane breath test (HMBT) in a patient following ingestion of lactulose. 

Following a “flatline” HMBT, we performed a hydrogen sulphide breath test. Patient values (orange) are plotted against normal values from our data set (blue). This patient responded positively to rifaximin, which would otherwise have been dismissed following initial HMBT result.

Coming soon……. Leaky Gut!

After many requests, we are currently investing in developing an in-house Gut Permeability test and we will be releasing more information in the new year.

Paediatric Lower GI Physiology Clinic: We are delighted to announce the official launch of our state-of-the-art Paediatric Lower GI Physiology Clinic. To spearhead this initiative, we welcome Eleni Athanasakos, an accomplished Lead Paediatric Scientist. Eleni will provide a comprehensive suite of services tailored for children, including anorectal manometry, endoanal ultrasound, defecating proctography, colonic transit studies, and biofeedback therapy. This addition empowers you to offer specialized care for the youngest patients, ensuring they receive the attention and expertise they deserve.

Other paediatric services: We are excited to announce the introduction of breath testing services within our repertoire of paediatric care offerings. These encompass hydrogen methane breath testing for Small Intestinal Bacterial Overgrowth (SIBO), hydrogen sulphide assessment, evaluation of carbohydrate malabsorption (lactose and fructose), H. pylori breath tests, and gastric emptying studies.

Furthermore, we extend our services to paediatric patients aged 14 years and older, providing comprehensive assessments such as oesophageal manometry, 24-hour pH studies, and studies on Laryngopharyngeal Reflux (LPR).

Expanded Private Services: Our commitment to accessibility extends to three new private service locations:

Nuffield Woking Hospital, Surrey

Spire Parkway Hospital, Birmingham


These facilities are now fully operational, catering to patients seeking upper and lower GI physiology assessments, as well as breath testing, in a private healthcare setting.

For streamlined referrals to any of our clinics, please complete the attached referral form or send us a clinic letter to admin@thefunctionalgutclinic.com