Contact number: 020 7806 4060
What is GI Physiology?
Gastrointestinal physiology refers to how the organs of the digestive tract – including the stomach, rectum, anus, and associated areas – work together to move, break down, and absorb food. If any part of this system isn’t working as it should, it can lead to uncomfortable symptoms and long-term digestive disorders.
Our GI physiology services include a variety of diagnostic investigations to assess the function of your GI tract, pinpoint possible causes of your symptoms, and guide your next steps for treatment or management.
Common reasons for referral include:
- Constipation or difficulty passing stool
- Faecal incontinence
- Gastro oesophageal reflux disease (GORD)
- Suspected food intolerances (e.g. fructose intolerance, lactose intolerance)
- Bloating, discomfort, or irregular bowel function
- Investigation of the back passage, rectum, or anus
GI Physiology Services at St John & St Elizabeth Hospital
Our private GI Physiology department offers a high quality service with experienced staff, advanced testing facilities, and a focus on patient care.
Why choose us:
- Range of Investigations: Including anorectal manometry, hydrogen breath testing (for lactose or fructose intolerance), and Helicobacter pylori screening
- Expert Team: Our tests are carried out by trained technicians and interpreted by experienced consultants in gastroenterology
- Calm Environment: Our department is welcoming and easy to access, making your appointment as comfortable as possible
- Fast Results: We aim to deliver clear results quickly, so you can move on to treatment or further management without delay
We understand that issues with digestion or the back passage can be difficult to talk about. Our team is here to support you with sensitivity and clarity throughout the investigation process.
Gut Health Tests we offer
- Oesophageal physiology studies (including pH measurement)
- High resolution oesophageal manometry
- Ambulatory 24h pH and impedance monitoring
- Hydrogen/methane breath test
How much does private gut health testing cost?
from £520*
The cost of private gut health testing is from £520* at St John & St Elizabeth Hospital.
*The price shown includes estimated hospital related costs associated with your treatment, from admission to discharge. The price does not include the cost of consultation, diagnostics, or the surgeon or anaesthetist fee.
This hospital from price is a guide price only and you will be offered a bespoke price depending on your surgery following pre-assessment depending on the type testing you require. Your consultant will advise you on this.
How to pay for your treatment
If you’re… paying for yourself
Did you know you don’t need private medical insurance to come to St John & St Elizabeth Hospital? As a self-pay patient, you can access safe, outstanding quality health care at times to suit you.
For scans and tests, as well as to see most consultants, you’ll still need to be referred by a medical professional like your GP, but as a self-pay patient, the process is more straightforward. You won’t need authorisation from an insurance provider, and you’ll have greater choice of consultant and appointment times.
If you’re… paying for yourself
Did you know you don’t need private medical insurance to come to St John & St Elizabeth Hospital? As a self-pay patient, you can access safe, outstanding quality health care at times to suit you.
For scans and tests, as well as to see most consultants, you’ll still need to be referred by a medical professional like your GP, but as a self-pay patient, the process is more straightforward. You won’t need authorisation from an insurance provider, and you’ll have greater choice of consultant and appointment times.
Frequently Asked Questions about GI Physiology Services
St John & St Elizabeth Hospital is located in St John’s Wood (NW8), with easy travel from Hampstead (NW3) and Kilburn (NW6):
By Tube:
St John’s Wood station (Jubilee Line) is a short walk away.
By Bus:
- Wellington Road: Routes 13, 46, 82, 113
- Circus Road: Routes 46, 187
- Abbey Road: Routes 139, 189
By Car:
We’re easily accessed from NW3 and NW6 via Finchley Road or Kilburn High Road.
We offer several tests that examine different parts of the digestive system, including:
- Anorectal manometry – to assess the strength and coordination of muscles in the anus and rectum
- Hydrogen breath tests – used to diagnose fructose intolerance or lactose intolerance
- Helicobacter pylori breath or stool tests – to identify infection in the stomach lining
- Transit studies – to assess how food moves through your GI tract
- Balloon expulsion or sensory testing – to evaluate bowel sensitivity and function
Your consultant will help decide which tests are suitable based on your symptoms and medical history.
SIBO Test
Small Intestinal Bacterial Overgrowth (SIBO) is a condition in the small intestine where bacteria, whether beneficial or harmful, proliferate excessively. This overgrowth can cause a wide variety of uncomfortable and often embarrassing symptoms for millions of sufferers.
Symptoms of SIBO can extend beyond digestion, often leading to conditions such as Chronic Fatigue Syndrome (CFS), rosacea, restless legs, cystitis, joint disorders, iron deficiency, and more.
Signs & Symptoms of Small Intestinal Bacterial Overgrowth:
- Diarrhoea: Typically associated with hydrogen-dominant SIBO
- Constipation: Usually linked with methane-dominant SIBO
- Alternating Constipation and Diarrhoea
- Gas and Flatulence
- Belching
- Severe Bloating
- Abdominal Pain and Cramps
- Leaky Gut (Intestinal Permeability)
- Acid Reflux
- Fatigue
- Lactose Intolerance
- Fructose Intolerance
Fructose Intolerance Test
This test evaluates your body’s ability to digest fructose, the sugar found in a range of fruits. Fructose intolerance can cause bloating, gas, and diarrhoea after consuming fruits.
Lactose Intolerance Test
This test evaluates your body’s ability to digest lactose, the sugar in milk and dairy products. Lactose intolerance can cause bloating, gas, and diarrhoea after consuming dairy.
Helicobacter Pylori Test
The Helicobacter Pylori (H. Pylori) test detects the presence of Helicobacter Pylori bacteria in your stomach, which can lead to peptic ulcers, stomach infections, and discomfort.
In most cases, yes. You can be referred by your GP or consultant. If you’re unsure how to arrange this, our department can help guide you through the process. If you’re already under care for gut function or digestive disorders, your specialist may recommend testing to help guide ongoing treatment.
Patients are typically referred for GI physiology services if they have ongoing digestive symptoms that haven’t responded to treatment, or when the cause of symptoms is still unclear after initial checks.
You may benefit from GI physiology if you’re experiencing:
- Persistent constipation or a feeling of incomplete bowel emptying
- Faecal incontinence
- Gastro-oesophageal reflux disease (GORD)
- Recurrent bloating, discomfort, or changes in bowel habits
- Suspected food intolerance (such as fructose intolerance or lactose intolerance)
- Concerns about gut motility or back passage function
Your GP or consultant may refer you directly, or you can contact us for further information about how to arrange an appointment.
When you book your appointment, we’ll provide clear instructions to help you prepare. This may include avoiding certain foods, medication, or fasting beforehand, depending on the procedure. If you are unable to attend, please contact us as soon as possible to reschedule.
Most GI physiology investigations are non-invasive or minimally invasive. Some may involve slight pressure or discomfort, especially during tests that assess the back passage, but they are usually well tolerated and do not require sedation. Our team will explain everything in advance and check in with you throughout your visit to ensure you’re comfortable.
After your tests, the results will be reviewed by your consultant or a specialist nurse. We’ll arrange a follow-up appointment to explain the findings, discuss any treatment needed, or suggest further investigations if required. We aim to return results quickly so you’re not left waiting for answers