Pale faeces

Pale or gray faeces can be caused by insufficient stomach bile output. Generally conditions such as gallstones, giardia parasitic infections, cholecystitis, cirrhosis, chronic pancreatitis or hepatities can cause this condition. The brown colour of faeces comes from bile salts generated in the liver.

Another common cause of pale faeces is aluminum hydroxide contained in antacids. A barium enema test can also cause faeces to become pale.

Undigested fat in faeces can cause a foul smell, make the faeces greasy or shiny, or cause the faeces to float.

Healthy faeces

There are several factors that can determine if your body is passing healthy faeces. The ideal colour for your faeces should be a medium brown and should leave your body with no discomfort or straining. The consistency should be similar to toothpaste and be around four to eight inches in length. The faeces should enter to water smoothly and sink slowly into the water. You should notice little odour or gas.

Black faeces

Black faeces with a foul odour could be the result of eating certain foods, consuming iron supplements, or even from internal bleeding.

If the black colour is from blood, it is known as melaena. The dark colour indicates that the blood has been in the body for some time, and is coming from higher up in the gastrointestinal tract.

A black stool caused by food, supplements, medication, or minerals is known as "false melaena." Iron supplements, taken alone or as part of a multivitamin for iron-deficiency anemia, may cause faeces to be black or even greenish in colour. Foods that are dark blue or black in colour may also cause black faeces.

A doctor should be consulted immediately if black faeces cannot be attributed to a benign cause, such as an iron supplement or a food.

Diagnosing melaena

The black colour alone is not enough to determine that it is blood that is being passed in the stool. Therefore, a doctor will need to confirm whether there is blood in your stool. This can be done in the office through a rectal exam. Or you may be sent home with a kit to collect a small stool sample that can be sent to a lab for evaluation.

The blood could be caused by several different conditions, including a bleeding ulcer, gastritis, esophageal varices, or a tear in the esophagus from violent vomiting (Mallory-Weiss tear). The tarry appearance of the stool is from the blood having contact with the body’s digestive juices.

After melaena is diagnosed, a physician may order other diagnostic tests to determine the cause and exact location of the bleeding. This could include x-rays, blood tests, colonoscopy, gastroscopy, stool culture, and barium studies.

Causes of melaena

Bleeding ulcer: An ulcer is a type of sore on the lining of the stomach, which can cause bleeding and result in melaena. Contrary to popular belief, stomach ulcers are not usually caused by stress or spicy food (although these can aggravate an already existing ulcer). In fact, they are typically caused by an infection with a bacterium called Helicobacter pylori (H. pylori). Antibiotics are normally prescribed to eliminate the infection.

Another cause of stomach ulcers is the prolonged use of pain medications known as NSAIDs (nonsteroidal anti-inflammatory drugs). NSAIDs can irritate the stomach by weakening the ability of the lining to resist acid made in the stomach. For this same reason, NSAIDs have an adverse effect on Crohn's disease and ulcerative colitis. NSAIDs include common over-the-counter drugs such as ibuprofen, naproxen sodium, and aspirin. Stomach ulcers caused by NSAIDs usually heal after the offending drug is discontinued.

Gastritis: Gastritis is the inflammation of the stomach lining and can be caused by overindulging in alcohol or food, eating spicy foods, smoking, infection with bacteria, or prolonged use of NSAIDs. Gastritis can also develop after surgery or trauma, or be associated with already existing medical conditions.

Esophageal varices: Esophageal varices are dilated veins located in the wall of the lower esophagus or upper stomach. When these veins rupture, they may cause blood to appear in the stool or vomit. Esophageal varices are a serious complication resulting from portal hypertension brought on by cirrhosis of the liver.

Mallory-Weiss tear: This is a tear in the mucous membrane that joins the esophagus and the stomach that may bleed and result in melaena. This condition is fairly rare (occurring in 4 of 100,000 people), and may be caused by violent vomiting, coughing, or epileptic convulsions.

Green faeces

Green faeces is a term to describe a green coloring or tint in faeces. Green faeces can be normal in some cases, such as in breast-fed infants.
Green faeces can also be caused by taking iron supplements or eating certain foods such as green leafy vegetables. Green faeces can also indicate a problem with food digestion due to a disease, disorder or other abnormal process.

The normal colour of faeces is generally light to dark brown. Faeces gets its color from bile, which is a yellow-green fluid produced in the liver that helps to digest your food. As food passes through your digestive tract, digestive enzymes break down the bile, resulting in various shades of brown faeces. When a disease or condition causes diarrhea, food passes through the digestive tract rapidly, and faeces may be green because digestive enzymes did not have time to turn the faeces brown.

Green faeces may be accompanied by other symptoms, which vary depending on the underlying disease, disorder or condition.

Green faeces can occur due to a normal or benign condition and not be a cause for concern. For example, you may produce green faeces after consuming certain iron-rich foods or iron supplements, leafy green vegetables, or products with green food coloring.

Faeces chart

The Bristol Stool Chart or Bristol Stool Scale is a medical aid designed to classify the form of human faeces into categories.
Sometimes referred to as the "Meyers Scale", it was developed by Dr. Ken Heaton at the University of Bristol and was first published in the Scandinavian Journal of Gastroenterology in 1997. The form of the stool depends largely on the time it spends in the colon (though there may be other contributing factors, including diet and illness).

The seven types of stool are:

    1: Separate hard lumps, like nuts (hard to pass)
    2: Sausage-shaped, but lumpy
    3: Like a sausage but with cracks on its surface
    4: Like a sausage or snake, smooth and soft
    5: Soft blobs with clear cut edges (passed easily)
    6: Fluffy pieces with ragged edges, a mushy stool
    7: Watery, no solid pieces. Entirely liquid

Types 1 and 2 indicate constipation, with 3 and 4 being the "ideal stools" especially the latter, as they are the easiest to defecate, and 5–7 tending towards diarrhoea.

Blood in faeces

Rectal bleeding can be caused by many reasons. Most commonly there will be only a mild bleeding, only on rare occasions can it be life-threatening. You should see a doctor immediately if the bleeding is heavy, or if you have black faeces (bleeding in the stomach or duodenum, known as melaena). If it is a mild bleed then you should not panic and make an appointment with your doctor for a diagnosis of the problem.

Rectal bleeding will often be used by doctors to mean any blood that passes out when you go to the toilet. Not all blood that can be passed will come from the rectum. In fact it can come from anywhere in your gut (gastrointestinal tract). The correct term is gastro-intestinal tract bleeding, or 'GI' bleeding.

If you have bleeding your doctor will need to asses the cause and severity of the bleeding. In most cases the bleeding will be mild and tests can be done as an outpatient as there is no immediate risk to life with a mild bleed. Always report to your doctor if you have a large amount of bleeding, urgent treatment is required for a large amount of blood loss.

Sometimes the bleeding from a gut condition can be mild, in which case you may not notice any bleeding and your faeces may not change colour. A test of your faeces will detect even small amounts of blood.

Bleeding could come from anywhere in the GI tract, generally:

Bleeding in the anus or rectum, the blood will be bright red and fresh.  You may notice blood after passing faeces and not mixed mixed in with the faeces. You may also notice streaks of blood covering faeces.

Bleeding from the colon, the blood may be mixed in with the faeces. The blood may also be darker red in colour.

Bleeding from the stomach or small intestine. The blood will have further to travel through the gut, the blood will become darker and can mix in the faeces. Your faeces may turn black or a plum colour, this is called melaena. This may occur due to a bleeding stomach. If you have melaena it is an emergency and can indicate a lot of bleeding from the stomach. You should contact your doctor immediately if you suspect that you have melaena.

Your doctor will ask questions to determine the possible causes of the bleeding. You may be asked questions regarding the symptoms such as pain, and the location and nature of any pain. If you have other symptoms such as diarrhoea or weight loss you should make these known to your doctor. Any mention anything else which you are aware of. An examination is likely to take place, this can involve your doctor examining your anus and rectum by inserting a gloved finger into your anus. Its possible that the diagnosis can be made after this examination. Test are commonly needed to clarify the initial diagnosis.

Some of the common causes of blood in the faeces are:

Haemorrhoids (piles). These are swellings that occur in the lower rectum and anus. Within the inside lining of the lower rectum and anus is a network of small veins. Sometimes these veins can be wider and engorged with more blood than usual. The engorged veins and surrounding tissue may then form in small swellings called haemorrhoids. About 50% of the people in the UK develop haemorrhoids at some stage. Small ones are usually painless. Larger ones may cause a mucus discharge, some pain, irritation and itching.

An anal fissure is a small tear in the skin of the anus. Generally this tear is less than a centimeter in length however can be very pain due to the sensitivity of the anus. An anal fissure will bleed a little after you pass faeces. This blood will be bright red and stains the toilet tissue, but soon stops.

A diverticulum is a small pouch with a narrow neck that sticks out from the wall of the gut. They can develop in any part of the gut, but generally occur in the colon. A diverticulum may occasionally bleed and you may pass some blood from your anus. The bleeding is due to a burst blood vessel that sometimes occurs in the wall of a diverticulum.

Crohn's disease is a condition that will cause inflammation in the gut. The disease flares up from time to time. Common symptoms include bloody diarrhoea, abdominal pain and general unwell feeling.

Ulcerative colitis is a disease of the colon and rectum, causing inflammation to occur. A common symptom is blood mixed with diarrhoea. The blood comes from ulcers that develop on the inflamed guts inner wall.

A bowel polyp (adenoma) forms on the inside lining of the rectum or colon and is a small growth. These mainly occur in older people. Aproximately 25% of people over the age of 50 develop at least one bowel polyp. They are non cancerous and usually will cause no problems. On rare occasions a polyp bleeds and can turn cancerous.

Cancer of the rectum and colon are common cancers in older people. Rectal bleeding is one symptom that could occur. Other symptoms may present themselves before visible bleeding occurs. For example pain, anaemia, weight loss, diarrhoea or consipation.

Angiodysplasia is a condition where enlarged blood vessels develop within the inner lining of the colon. The cause is unknown and commonly occur in older people. Bleeding from angiodysplasia in painless. The visible blood can range from bright red to dark blood mixed with faeces, to melaena (black faeces).

Various abnormalities of the gut or gut wall may cause rectal bleeding in your children.

An ulcer of the stomach may bleed and may cause melaena.

A gut infection may cause bloody diarrhoea due to the infection causing an inflammation of the gut.

If you have rectal bleeding and it is heavy bleeding or if you have melaena then you should seek medial assistance urgently. If you are feeling dizzy or collapse then you should contemplate calling an ambulance. For mild bleeding you should make an appointment to see your doctor. Some people will assume that rectal bleeding is due to haemorrhoids and do not consult a doctor. You should not assume that it is related to haemorroids and should seek a proper medical examination from a doctor.

Depending on the possible cause of the bleeding, common test would include a colonoscopy or sigmoidoscopy. A colonoscopy is a test where a small camera is inserted into the anus and into the colon. It is about as thick as a finger and will allow the doctor to see inside your colon. A small biopsy may also be taken for further analysis. A sigmoidoscopy is a similar examination however the lower colon or rectum is examined and is easier to perform than a full colonoscopy.

A faecal occult blood test (FOB) will detect small amounts of blood in your faeces which you may not normally see or detect. Some disorders will only leave a small trace of blood in the faeces. A FOB test will detect small amounts of blood, however it will not detect where the blood is coming from. A small sample of faeces will be smeared onto a piece of card, this may be done in the doctors surgery and sent away to a lab for testing. You can be issued with a home test kit for performing this at home. Sometimes more than one test will be performed due to some bleeding disorders that only bleed now and then.

You should always seek expert medical advice from your doctor if you are concerned about finding any blood in your faeces.