Virtual Medical Centre

Symptoms

Diarrhoea

• Definition
• Mechanisms of the formation of diarrhoea
• Causes of diarrhoea
• Signs and symptoms of diarrhoea
• Investigations

Definition

Diarrhoea is a common digestive disorder that virtually all people will suffer at some stage during their lives. The definition of diarrhoea varies but it can generally be taken to mean increased stool water causing an increase in stool frequency or the passage of soft stools. Passage of greater than 3 stools per day or a stool volume of greater than 200mls suggests the diagnosis of diarrhoea. Diarrhoea is called acute if lasts for less than two weeks or chronic if it lasts for greater than 4 weeks. Diarrhoea can occur in virtually any person regardless of their age and general health. Diarrhoea can range from a mild discomfort to a severe and life threatening illness due to the risks of dehydration. In fact diarrrhoeal diseases are one of the top causes of death worldwide and it bcomes particularly common in developing countires with poor food practices and hygiene.

Children and the elderly are particularly prone to dehydration secondary to diarrhoea. However, the great majority of cases of diarrhoea follow short courses which don't really require specific diarrhoea treatment to resolve.

Mechanisms for the formation of diarrhoea

Diarrhoea basically develops when there is a defect in the absorptive mechanism working in the intestines. This may be due to damage to the mucosa (lining of the bowel) from infections or inflammation or excess secretion of fluid and electrolytes from particular toxins (e.g. cholera). Sometimes there may be too much sugary material in the lumen of the bowel which draws more fluid across the membranes. In other patients the bowel may just be overactive from hormone disorders which causes very frequent bowel motions but the overall volume should remin approximately the same.

Causes of diarrhoea

By far the most common cause of diarrhoea is infection. Most cases are just mild viral infections caused by rotavirus (which some people may refer to as the stomach flu). This can be easily spread through daycare cantres, schools or families. Bacteria such salmonella, campylobacter and shigella are other common causes of diarrhoea. These cases tend to be more severe than viral diarrhoea and are caused by eating food or drinking water contaminated with these bacteria. Diarrhoea can sometimes be caused by parasites which are transmitted by similar mechanisms. Giardia lamblia and cryptosporidium are possible parasitic causes of diarrhoea. Chronic diarrhoea can be caused by a number of medical problems. Irritable bowel syndrome is relatively common and associated with alternating periods of diarrhoea, constipation and bloating. Certain medications, particularly antibiotics and anti-cancer drugs can cause diarrhoea because they disrupt the normal healthy bugs in the intestines and inhibit mucosal cell regeneration respectively. Inflammatory bowel diseases which include Crohn's disease and ulcerative colitis also cause recurrent attacks of diarrhoea often stained with blood and mucus. Colorectal cancer or any other defects in the intestines may also cause diarrhoea.

Signs and Symptoms of diarrhoea

The signs and symptoms of diarrhoea include:

• Passage of frequent, loose and watery stools.
• Abdominal cramps or pain.
• Fever- Particularly if there is an infectious cause.
• Bleeding- Bacteria and parasites often can produce bloody diarrhoea (dysentery). In addition inflammatory bowel disease, polyps and colorectal cancer cause blood and mucus in the stools.
• Nausea and vomiting may also be present in the case of infection.

Important points in the history of diarrhoea:

Your doctor will ask you lots of questions so they can try to determine the likely cause of your diarrhoea in order to treat it. These questions will include:

• How long have you had diarrhoea?
• What is the clour and consistency of your stool?
• Any blood or mucus?
• Any other symptoms or fever?
• Do you have abdominal pain with the diarrhoea.
• Anybody else in the family sick?
• Have you recently been overseaes?
• Which medications do you take?
• Do you smoke? How much alcohol do you drink?
• Are you on a special diet?

The doctor will then briefly examine you to to check for signs of anaemia and dehydration. Your abdomen will also be caefully examined.

Investigations

The doctor will then order a number of tests to determine the likely cause. These will include:

• Blood tests- Looking at blood counts and haemoglobin to determine any anaemia due to bleeding and to look for the possibility of infection.
• Stool examination- Samples of stool will be examined under the microscope to see if there are any pathogens identifiable.
• Sigmoidoscopy, colonoscopy or barium examination may be used to visualise the bowel to determine if inflammatory bowel disease, polyps or suspected malignancy (cancers) are present. Patients with chronic diarrhoea often have extensive tests to determine the most likely cause.