Stool blood can be red, brown and purple, black and tarred or hidden (not visible to the naked eye). 
The causes of blood in stools are harmless disorders of the gastrointestinal tract, such as hemorrhoids to serious diseases such as colon cancer .


Type of rectal bleeding

There are two possible sources of blood in the stool: the upper digestive tract (stomach and small intestine) and the lower digestive tract (colon, rectum, and anus). 
The bleeding  of the upper digestive tract usually causes black and tarry stools. 
Bleeding from the lower digestive tract is commonly seen because faeces are lined or mixed with bright red blood. 
Certain foods and medicines can cause blood in the stool. 
However, it is not always possible to know the origin or type of rectal bleeding, according to the appearance of the stool. 
Sometimes the amount of blood is small and may be visible only on toilet paper. 
A physical examination and evaluation of the doctor are necessary in most cases.
Sometimes bleeding in the gastrointestinal tract may be too slow to cause rectal bleeding. 
In these patients, the bleeding is hidden (not visible to the naked eye). The blood is only found by stool analysis (fecal occult blood test) in the laboratory. 
Occult bleeding has many causes similar to rectal bleeding and can cause the same symptoms. 
It can occur along with anemia that is caused by loss of iron in the blood ( iron deficiency anemia ).


Causes of blood in the stool

Possible causes of blood in the stool are:

Diverticulitis. The diverticula are small pockets that form on the wall of the colon. Diverticula usually do not cause problems, but can sometimes bleed or become infected.

Anal fissure. It is a small cut or tear in the lining of the anus lining, similar to the cracks that occur on the cracked lips. Anal fissures are caused by large, hard stoolsthat cause pain during bowel movements and blood that can be seen when the person cleans.

Colitis or inflammation of the colon. Among the most common causes of blood in ocassional feces (occurring from time to time) are  infection or inflammatory bowel disease.

Angiodysplasia. A disease in which abnormal and fragile blood vessels cause bleeding.

Peptic ulcers. An open lesion on the inner wall of the stomach or duodenum, the upper extremity of the small intestine. 
Many peptic ulcers are caused by infection with a bacterium called Helicobacter pylori . Long-term intake of anti – inflammatories such as aspirin, ibuprofen and naproxen may cause chronic gastritis and ulcers .

Gastroenteritis or intestinal flu. The gastroenteritis is a viral or bacterial infection of the stomach and intestines that the immune system normally resolve in a few days. It can cause diarrhea with traces of blood and mucus , as well as symptoms such as stomach pain and vomiting .

Polyps or cancer
The polyps are benign growths that can grow, bleed and become cancerous. 
They often cause bleeding that is not visible to the naked eye.

The stomach cancer can cause blood in the stool.

Problems with the esophagus . The esophageal varices (veins) or the esophagus tear can cause significant blood loss.

Trauma or foreign body

Vascular malformation (abnormal structures of blood vessels called arteriovenous malformations). 
This disease can also cause liquid feces with blood.

Endometriosis . This disease can cause blood in the stools of women before and during the menstrual cycle .


What can cause blood in the stool during pregnancy?

Generally, rectal bleeding is caused by hemorrhoids which are the blood vessels in the rectum that get bigger and get inflamed. 
Hemorrhoids are relatively common during pregnancy , especially in the last trimester and in the weeks after delivery.

The anxiety and stress promote constipation and so the inflammation of hemorrhoids. 
Whoever suffers a laceration of the veins during an evacuation, if the stools are hard and rubs with much energy during the cleaning with toilet paper, these swollen veins can bleed. 
Anal fissures are another cause of rectal bleeding. These painful lesions of the anus skin can be caused by the evacuation of hard stools due to the constipation that is common during pregnancy.


Blood in the stools of children

Anal fissures – anal fissure can occur in all age groups, from infants to children to school to the elderly. 
The symptoms of anal fissure are pain and bright red blood in stool or toilet tissue.

Intolerance of milk or soy protein , also known as milk allergy, milk-induced enterocolitis or proctocolitis is a disease that affects newborns. 
It can also occur in children who drink breast milk if the mother drinks milk or soy products. 
Protein intolerance usually resolves at 1 year of age. 
Symptoms of milk and soy protein intolerance include vomiting and diarrhea, in addition to blood in the stool or blood-dung droppings. 
Therapy is a milk-free diet.

Less common Causes
Inflammatory bowel disease, also known as Crohn’s disease or ulcerative colitis , are diseases that cause inflammation of the intestinal wall. Inflammation and ulceration cause symptoms such as blood in the stool, diarrhea, loss of appetite, and weight loss .

Infectious diarrhea Infectious
diarrhea is caused by a virus, bacteria or parasite that can cause blood in the stool in children in preschool and school age.

Infectious diarrhea can develop after eating contaminated food and beverages or after taking a course of antibiotics . 
The symptoms of infectious diarrhea are usually belly pain , fever and blood in the soft stools.

The juvenile polyps are formations that can develop between two and eight years. Generally, the symptom is painless rectal bleeding. 
Juvenile polyps are not usually cancerous or precancerous, but should be evaluated by a physician and usually need to be removed.

Some more serious diseases, including intestinal invagination (a form of bowel obstruction) or Hirschsprung’s disease or intestinal aganglionar megacolon (that is, a form of bowel obstruction that develops before birth due to lack of some nerves) can cause blood in the feces 
The obstruction is the medical term for an intestinal blockage. 
Most of these diseases cause sudden discomfort of the newborn


When to worry? Diagnosis of blood in stool

It is important to visit a doctor to check the blood in the stool. 
For example, pitch black stools may be caused by a peptic ulcer or other problem in the upper digestive tract and may be accompanied by stomach pain. 
Live red blood or brown colored stools usually indicate a problem in the lower digestive tract, such as hemorrhoids or diverticulitis . 
After seeing the medical history and after the physical examination, the doctor may order tests to determine the cause of the bleeding.

Who to contact? 
The medical specialist is the gastroenterologist.


What exams do:

Endoscopy . This is a procedure that involves the insertion of an endoscope into the digestive system through the mouth and the esophagus, stomach and duodenum. 
The endoscope is a flexible tube with a tiny camera at the end. 
Endoscopy can also be used to collect tissue samples for microscopic examination (biopsy).

A procedure in which a device called the colonoscope is inserted through the rectum to visualize the colon. As with endoscopy, colonoscopy can also be used to collect tissue samples for biopsy.

A procedure similar to colonoscopy and endoscopy is performed to examine the small intestine. 
In some cases, you need to swallow a capsule with a small camera that transmits images to a monitor as it passes through the digestive tract.

Barium enema. 
A procedure that uses a contrast material called barium to make the digestive system visible on the radiograph . Barium can be ingested or inserted into the rectum.

A procedure that involves injecting a special dye into the vein. This substance allows you to see the vessels with an X-ray or CT scan. 
The procedure detects bleeding because the dye leaks from the blood vessels and accumulates at the point where it has bleeding.

A surgical procedure in which the doctor makes several small incisions and examines the abdomen. 
This may be necessary if the other tests can not identify the cause of the bleeding. 
Doctors also require lab tests when there is blood in the stool. These tests can control the problem of bleeding, anemia and Helicobacter pylori infection.


Stool blood treatment

Treatment varies depending on the cause and includes medications such as:

  • Antibiotics for the treatment of Helicobacter pylori
  • Anti-inflammatory drugs to treat colitis,
  • Surgery to remove polyps or damaged parts of colon cancer, diverticulitis or inflammatory bowel disease.

Treatments may also include creams and suppositories for hemorrhoids. 
In many cases, however, therapy involves simple natural remedies that can be done at home.

The remedies can be:

A high fiber diet to relieve constipation that can cause and aggravate hemorrhoids or anal fissures;

We recommend eating plenty of fruits (especially plums) and vegetables (eg zucchini, green vegetables, avoid eating fried, meat, dairy and sugar; 
. Remain sitting in a hot or salty bath to relieve symptoms of cracking and promote healing 
Swimming in the sea is an excellent remedy because salt water is therapeutic.There 
are a few people with few platelets that take months to complete healing after a cut or a bruise.If 
these individuals get into sea water they accelerate the closure of the lesion and the formation of skin normal.

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