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Diarrhoea is a common condition that most people suffer with from time to time, and there are a variety of treatments available with London Gastroenterology Centre.

The causes of diarrhoea are wide and varied. If it lasts for less than 3 weeks, it may be part of a self-limiting infection but if there is blood in the stool you should not wait. Please arrange to see the doctor. If the diarrhoea lasts for more than 3 weeks it should be investigated, whether there is blood in the poo or not.

Tests include stool and blood analysis. If these do not show the cause, more complex tests may be needed. We are able to offer the full range of investigations and treatments.

For many people with on-going diarrhoea, it may be part of the irritable bowel syndrome, which affects up to 1 in 10 people at any one time. Often dietary advice is helpful here and we have specialist dietitians who can advise you.

For some others, diarrhoea is a symptom of a more serious disease which may need specialist treatment. Whatever the cause, the London Gastroenterology Centre offers a full diagnosis and treatment service. Please contact us to arrange your appointment.

Symptoms of Diarrhoea

Diarrhoea is a symptom of many gastrointestinal (GI) conditions where an individual may pass loose watery stools and also the frequency may be more, more than three times a day. The stool becomes watery because of increased water in the stool and the causes may be many.

Excessive liquid may accumulate in the colon because of increased secretion of water into colon from stomach, pancreas, and the intestine; faster movement of liquid or undigested food into the small intestine and colon; poor absorption of water in distal intestine and colon; or the combination of one or more of these conditions.

Often patients with diarrhoea may also have other symptoms such as cramps, abdominal pain, dehydration, urgency to pass a bowel, irritation in the anus, nausea and vomiting. These are considered as uncomplicated symptoms. However diarrhoea accompanied by fever, loss of weight, or bloody stool is considered complicated and require immediate medical treatment and intervention.

Types of Diarrhoea

Diarrhoea is of two types; acute and chronic diarrhoea.

Acute diarrhoea

Acute diarrhoea is a condition of watery stools that usually lasts for only few days and is usually due to infection. Acute diarrhoea is very common. People get it after eating incompletely cooked food, often at a restaurant. It can also happen on holiday, the so-called ‘travellers diarrhoea’. In these settings it may not require formal diagnosis if it is self-limiting and there is no obvious bleeding.

Chronic diarrhoea

This is diarrhoea that last for more than three weeks and may require formal diagnosis to identify the exact cause and appropriate treatment.

The causes of chronic diarrhoea are wide and varied and a large number of tests may be needed to identify the precise cause. Doctors need to consider intolerance to certain foods or medicines, intestinal diseases such as Crohn’s and ulcerative diseases, malabsorption, certain types of cancers, an over-active thyroid and alcohol abuse, to mention just a few!

Your doctor may ask you to avoid certain foods such as lactose, carbohydrates or wheat to check the body’s response. The doctor may also recommend special tests such as sigmoidoscopy or colonoscopy where a thin, flexible tube will be passed into the bowel. It enables the doctor to look for inflammation and to look for other intestinal abnormalities.

Causes of diarrhoea include infections which can sometimes cause inflammation of the lining of small intestine or produce toxins which secrete more fluid from intestinal walls, intolerance to certain foods or medicines, intestinal diseases such as Crohn’s and ulcerative diseases, malabsorption, certain types of cancers, hyperthyroidism, diabetes, and alcohol abuse.

Treatments are equally varied and range from medicines, to dietary changes, complementary approaches and rarely, surgery.

Tests for Diarrhoea

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Stool Assessment

One of the best ways for you and your doctors to gain a better understanding of your symptoms/illness is to keep a stool diary, which involves making notes regarding different aspects of your toilet habits. Your doctor will ask you to keep a record of stool frequency, volume, whether you strained during the bowel movement or felt like you had not fully emptied your bowel at the end, and to describe the stool itself using the Bristol stool scale, shown below.

How your stool compares to these different types can be a good indicator of your general bowel health.

Stool types 1 and 2 are an indication of constipation.

Stool types 3 and 4 are considered to be “normal”.

Stool types 5, 6, and 7 indicate progressive forms of diarrhoea.

Stool tests

Only a very small amount of stool is needed for this test. Collecting it is not much fun but it is not difficult. You will be given a pot with a lid. The lid has a little spoon attached. All you need to do is to ‘scoop some poop’ into the spoon and put it into the pot.

The best type of stool to send the laboratory is liquid or semi-solid. It also needs to be delivered to the hospital laboratory fresh. So if you produce your stool in the middle of the night, please put it in the pot and place it in a cold place. If you cover it, the fridge is an excellent place to store a sample for a few hours. As soon as the hospital laboratory is open, deliver it there directly.

Tests performed on stool for infection usually include looking for bacteria including E coli, Salmonella, Shigella and Campylobacter. Stools may also be examined for parasites, ova and cysts. These are produced by many tiny organisms such as Giardia lamblia, which is an important cause of intermittent diarrhoea.

Blood tests

Simple blood tests can sometimes point clearly to the cause of diarrhoea. For example, raised inflammatory markers like the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) may point to a diagnosis of inflammatory bowel disease. Specific Immunoglobulin A (IgA) Deficiency is an unusual cause of diarrhea and easily detected as is an overactive thyroid, which can cause a combination of fast heartbeat, anxiety and diarrhoea.

Endoscopy (also known as Gastroscopy)

An endoscopy (gastroscopy) is a procedure performed by a specialist. It involves taking a look at the upper portion of your digestive tract. To do this, the doctor inserts a camera attached to a long flexible tube down your food-pipe (oesophagus) into your stomach, and possibly into the upper section of your small intestine (the duodenum). Usually a small sample (biopsy) will be sent to the laboratory to check for conditions such as coeliac disease and giardia infection.

Faecal calprotectin

This new stool sample test is a good way to exclude inflammation in the bowel. If it is negative, it is unlikely you have ulcerative colitis or Crohn’s disease.


This test is often needed to check for inflammation and polyps, both of which can cause diarrhea. We are careful to consider whether a faecal calprotectin can replace colonoscopy. This is a sensible and reasonable approach in some, but not all, patients.

Virtual colonoscopy (CT pneumocolon)

This is a non-invasive way of looking for polyps or cancer in the bowel. It is not yet quite as good as colonoscopy although it continues to improve. If a polyp is found, you will still need to have a colonoscopy to remove it.

Faecal occult blood testing

This test is the basis of the UK colon cancer screening programme. It is an excellent way of detecting people who do not have symptoms but might have early bowel cancer. The problem is that for a person with symptoms, a negative test is not good enough to exclude cancer. If you have symptoms, please do not rely on this test.

Specialist Tests

Before having specialised tests for diarrhoea predominant IBS, it is important that the standard blood, stool and endoscopy tests have been done. If these are normal, you may require one or more other tests. These include

• SehCAT study for bile salt malabsorption
• Lactulose hydrogen breath test for small intestinal bacterial overgrowth (SIBO)
• Smart Pill physiology study for various problems including caecal malfermentation
• Lactose hydrogen breath test for lactose intolerance

SehCAT study for Bile Salt Malabsorption

If you have on-going chronic diarrhoea, a possible cause is the inability of your body to re-absorb bile acids, a substance produced by your liver to break down the fats in the food you eat.

Normally these bile acids are released into the top of the small bowel. They are then re-absorbed back into the body at the bottom of the small bowel.

If your body can’t re-absorb these bile acids properly, they escape from the small bowel into the large bowel. This causes diarrhoea, similar to that caused by IBS.

When you go for the test you will be asked to swallow a tablet, which contains a special labelled form of bile acid. One week later, you will have a scan to see how much of the label remains in the body

If the test shows that you aren’t absorbing bile acids properly, then you can be treated with drugs to help soak up the excess bile. This should stop the diarrhoea.

Lactulose hydrogen breath test for Small Intestinal Bacterial Overgrowth (SIBO)

A condition called small-bowel bacterial overgrowth (SIBO), where there is an excess of bacteria in your intestines, can cause diarrhea but it can also cause constipation and abdominal discomfort.

SIBO occurs in many people who have had abdominal surgery or cancer treatment such as radiotherapy. It can also occur without any obvious cause.

During the test you will be given a drink containing lactulose and asked to give a sample of breath every 15 minutes for 2-3 hours. If the levels of hydrogen in your breath are higher than average it is an indication that you may be suffering from small-bowel bacterial overgrowth, and you will most likely be given antibiotics to treat the condition.

Lactulose is a special type of sugar. It tastes sweet, but it is not absorbed through the wall of the gut into the body. It is therefore safe for anyone to use, including people with diabetes.

Correct preparation is very important. Before the test, you will be asked to leave out certain foods for a couple of days. This makes sure that the test result is accurate. Please follow the instructions you are given carefully.

Small bowel physiology – the Smart Pill test

This is a very new test. It involves swallowing a small, disposable capsule that travels through your digestive system, sending information back to a measuring device that you carry around with you. It works wirelessly.

The test can take a total of 3-5 days, during which you go about your normal business; once the pill has passed right through your digestive system, your doctor will take a look at the recordings it has made and use them to aid their diagnosis.

The pill can relay all kinds of information about your small bowel, including intestinal motility, pH, temperature and pressure. The combination of results the pill gives will determine the most accurate diagnosis.

This test is not widely available. But if one of the London Gastroenterology Centre doctors thinks it is useful for you, we are pleased to tell you that we can organise this test easily.

Lactose Hydrogen Breath Test

Lactose intolerance can cause diarrhea and is easily tested for. The breath test is similar to the lactulose hydrogen breath test.

You will be given a drink containing the sugar lactose (which is safe for diabetics to take) and asked to give a sample of breath every 15 mins for 2-3 hours. If the levels of hydrogen in your breath rise higher than average it is an indication that you may be suffering from an intolerance to lactose. If you are diagnosed as lactose-intolerant, your symptoms may be controlled by avoiding dairy products or by taking supplements which replace the natural lactase enzyme.

Diarrhoea Treatments

Treatment for diarrhoea depends on the cause of the condition. Certain over-the-counter anti-diarrhoeal medications may be prescribed to treat mild diarrhoea. However, these should be avoided by patients passing bloody stools.

If the diarrhoea is caused by infection, antibiotics may be prescribed. Absorbents may also be prescribed by the doctor. These help by binding the water in the small intestine and colon and make the stool harder.

Anti-motility medications may be given to relax the muscles of the small intestine and colon and create more time for the water to be absorbed. If there is narrowing of the intestinal muscles (cramps) anti-motility medications may also help in relaxing the muscles.

At home, you may have to avoid taking caffeine and foods that are high in fibre and sweet as they may worsen the condition. If you are allergic to lactose, then yoghurt is considered to be a better option and may help you to recover fast.

To book a private consultation with our specialists, or to discuss diarrhoea treatments at our London clinic, please get in touch using the form below.

Videos explaining travellers diarrohea

We are available to see patients daily.

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