DIARRHOEA

by Dr Kieran Moriarty, Bolton General Hospital

What is a normal bowel habit ?

People vary a lot in how often they open their bowels - usually between three times a day and three times a week in the U.K. A stool should be solid, but moist and easy to pass.

What does the bowel do ?

Receives food and liquid we eat and drink. Absorbs most of the nutrients from food and drink into the blood-stream. Secretes fluid from the body into the gut. Propels its contents from the stomach down the length of the bowel to the back passage (anus). Excretes waste material as stool.

What is diarrhoea ?

Diarrhoea means there are frequent, loose or liquid stools. There may be a gripey abdominal pain (colic) which is less after a stool is passed.

Acute diarrhoea - comes on suddenly and lasts a short time.

Chronic diarrhoea - affects someone over a long period of time. Some people pass frequent, small solid stools with a sense of urgency. This is not true diarrhoea and occurs when the rectum is irritable as in the irritable bowel syndrome or inflamed as in colitis.

What causes diarrhoea ?

Too much fluid is passed (secreted) from the blood-stream into the bowel, for example in gastroenteritis. This is how some laxatives work. The bowel moves its contents through too quickly and too little fluid is passed back into the bloodstream. This is one way in which anxiety produces diarrhoea. More liquid is drunk than the bowel can cope with - this seldom happens, but is one way in which drinking too much beer can cause diarrhoea.

What causes acute diarrhoea ?

Food poisoning. Gastroenteritis (see separate leaflet on the prevention and treatment of travellers’ diarrhoea). Anxiety. Sometimes treatment with an antibiotic. Alcohol (to excess).

What causes chronic diarrhoea ?

When diarrhoea goes on for a long time, the most likely cause is the irritable bowel syndrome. It is called a ‘functional’ condition. This means that the bowel produces stools which are looser or more frequent than normal, although the bowel is not diseased.

Less commonly, there are also several conditions which cause chronic diarrhoea:

• inflammation of the bowel - eg. ulcerative colitis or Crohn’s disease. The diarrhoea in ulcerative colitis often contains blood
• poor absorption of food - eg. coeliac disease or chronic disease of the pancreas, when the stools may be very pale, offensive smelling and difficult to flush away
• hormonal changes - eg. diabetes or an overactive thyroid gland
• some bowel cancers
• chronic bowel infections
• some stomach operations
• some drugs including antibiotics, magnesium-containing antacids, pills for blood pressure or arthritis and laxatives
• foods including milk in some people who digest milk sugar (lactose) poorly and wheat products in patients with coeliac disease and consumption of unusually large amounts of alcohol. True food allergy is very rare.

When should I consult my doctor ?

After a few days if acute diarrhoea does not settle.

Earlier for:
- severe diarrhoea with dehydration
- the elderly and the very young (under 2 years).

You should ask for an early appointment with the doctor if liquid stools contain blood and/or if you are losing weight.

What will the doctor do?

• After listening to you and doing a general examination, the doctor will usually examine the rectum (back passage) with a finger. The doctor may:
• pass an instrument through the back passage to examine the lining of the bowel arrange laboratory examination of stool samples to see if there is infection
• arrange blood tests
• arrange a barium X-Ray examination of your bowel. (A barium enema involves the insertion into the rectum of a harmless material which shows up on an X-ray, allowing the doctor to see any abnormalities)
• arrange a flexible sigmoidoscopy or colonoscopy (inserting a flexible telescope into the back passage so the doctor can see the whole or part of the colon).

How is diarrhoea treated?

Acute Diarrhoea (usually improves within a few days).
Ask yourself whether this is due to anxiety, medicines or alcohol.
Keep up a good fluid intake, using rehydration solutions when much liquid is passed to replace lost fluid and salt.
Observe good hygiene, in case the diarrhoea is infectious.
Wash your hands thoroughly after going to the toilet.
Don’t prepare food for other people, especially babies and old people.
Consider taking an anti-diarrhoeal drug such as loperamide or diphenoxylate which can be obtained for adults without a prescription if the symptoms are severe, but always read the label and ask your pharmacist for advice if unsure.
IT IS DANGEROUS TO GIVE THESE TO BABIES AND CHILDREN WITHOUT MEDICAL ADVICE.
The doctor may prescribe an antibiotic if a severe infection is diagnosed or suspected.

Chronic Diarrhoea (continuing for weeks or months)
Do not treat yourself without seeing a doctor. There may be an underlying disease which can be cured. In most cases, chronic diarrhoea is not serious and can be controlled by medicines, but this is best done under medical supervision.

What is spurious diarrhoea?

In severe constipation where the lowest part of the large bowel (rectum) is very full, small amounts of liquid bowel contents may leak past the solid stool giving rise to a kind of diarrhoea. Treatment involves emptying the bowel using laxatives or enemas.

(Irritable bowel syndrome, faecal incontinence, travellers’ diarrhoea, coeliac disease and spurious diarrhoea due to constipation in childhood are discussed in separate leaflets available from the DDF. Please enclose a stamped-addressed-envelope).

The need for research

Each year, 5-10 million small children in the Third World die of diarrhoeal diseases, such as cholera. Rehydration solutions to replace vital lost glucose and salts have saved many lives. We urgently need research leading to improved treatment for people with severe diarrhoea and for those where chronic diarrhoea makes life miserable.

Vaccines against infectious diseases, such as cholera, are being developed. These could be a major breakthrough in the fight against diarrhoeal disease.