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The Gastrointestinal Function Unit provides physiological diagnostic services to gastroenterologists, surgeons, respiratory physicians, ear nose and throat surgeons and some vascular specialists.

Patients referred for these tests usually suffer from swallowing difficulties, heartburn, acid reflux and reflux associated with cough, aspiration, voice changes, and sometimes asthma.

The Gastrointestinal Function Unit (GIFU) at St James’s Hospital, established in 1987, was the first unit in Ireland and has been a de facto national referral centre for physiological investigations of the oesophagus and stomach. 

  • Our investigations include:

    • High-resolution manometry
    • High-resolution impedance manometry
    • 24hr pH profile
    • 24hr laryngo-pharyngeal pH profile
    • 24hr pH impedance
    • Hydrogen methane breath testing
    • We only take referrals for hospital medical doctors
    • If you have a query about your appointment out of office hours, please leave your name, phone number and date of birth, with a short message on the answering machine.
    • Please make sure you read your patient information sheet when you receive it.
    • All of our tests require you to fast from midnight and you may have to stop certain medications a week beforehand
  • The unit is staffed by clinical measurement physiologists who have specialised in gastrointestinal physiology.

  • We do not accept referrals directly from GPs.

  • This examination tests how the muscle in your gullet works. The gullet is a muscular tube that is responsible for the movement of food from the mouth to the stomach.  At the lower end of the gullet, there is a valve, which controls the entry of food into the stomach. This valve also prevents food and acid coming back into your gullet.

    Typical symptoms that you may experience may be swallowing difficulties, chest pain or bringing back up food into your gullet. The swallow test takes approximately 40 minutes. A small tube will be inserted through your nose and into your stomach. During this time you will be able to breathe, swallow and talk easily. You may be asked to take small amounts of water and bread during the test. You may be able to avail of a numbing spray before your test to help you swallow the tube.

  • pH is the term used to measure the level of acidity. The lower the level of pH, the more acid is detected. Long episodes of acid reflux into the gullet can cause symptoms such as heartburn and chest pain.  Mild heartburn is very common and can be treated with antacids.  Stronger tablets or surgery may be needed for the treatment of severe heartburn. 

    The 24-hour acid test records the frequency and duration of acid reflux into the oesophagus during eating, sleeping, and daily routines.

    If you are having an acid test, you will have it straight after your swallowing test. A small tube will be put into your nose and placed just above the valve at the entrance of your stomach. The tube will be taped in place and looped over your ear and under your clothes.  It will then be connected to a monitor that is worn around your waist for the rest of the day. You can eat as normal during the test. You will need to return to the hospital the following day to have this monitor removed.

    You will not be admitted overnight into hospital for this examination.

  • Small intestinal bacterial overgrowth (SIBO) occurs when there are too much bacteria in the small intestine. It is a common underlying cause of irritable bowel syndrome (IBS). When there is an overgrowth of bacteria in the small intestine, it can interfere with digestion and absorption. As a result, gases are produced when the bacteria breakdown food entering the intestine from the stomach. This may lead to gastrointestinal symptoms such as bloating, nausea, and diarrhoea.

    The hydrogen and methane breath test is used to detect (SIBO). This is a simple investigation. You will be given a test solution to drink and after that, you will be asked to blow into a breath analyser/ bag every fifteen minutes for up to three hours. Between samples, you are free to read a book or watch your tablet.

    We can also test for carbohydrate malabsorption/ intolerance testing for fructose, lactose, glucose and sucrose malabsorption.

Contact Details

Monday - Thursday, 7.45am to 4.30pm
Friday, 7.45am to 1pm

How to find us

Ground floor, main hospital building

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