Blood in the Stool (Rectal Bleeding) ( courtecy;- MEDICINE.NET )

    

 

Rectal bleeding (blood in stool) definition and facts

·         Rectal bleeding is the passage of blood through the anus.

• The bleeding may result in bright red blood in the stool as well as maroon colored or black stool. The bleeding also may be occult (not visible with the human eye).
• The common causes of rectal bleeding from the colon include
• anal fissure,
• hemorrhoids,
• diverticulosis,
• colon cancer and polyps,
• colonic polyp removal,
• angiodysplasias,
• colitis,
• proctitis, and
• Meckel's diverticula.
• Rectal bleeding also may be seen with bleeding that is coming from higher in the instestinal tract, from the stomach, duodenum, or small intestine, for example, Meckel's diverticulum.
• Rectal bleeding may not be painful; however, other symptoms that may accompany rectal bleeding are diarrhea, and abdominal cramps due to the blood in the stool.
• Rectal bleeding is commonly evaluated and treated by gastroenterologists and colorectal or general surgeons. The origin of rectal bleeding is determined by history and physical examination, anoscopy, flexible sigmoidoscopy, colonoscopy, radionuclide scans, visceral angiograms, flexible endoscopy or capsule endoscopy of the small intestine, and blood tests.
• Rectal bleeding is managed first by correcting the low blood volume and anemia if present with blood transfusions and then, determining the site and cause of the bleeding, stopping the bleeding, and preventing future rebleeding.
• Rectal bleeding can be prevented if the cause of the bleeding can be found and definitively treated, for example, by removing the bleeding polyp or tumor. In addition, it may be appropriate to search for additional abnormalities, for example, polyps or angiodysplasias that have not yet bled but may do so in the future. This may require either gastrointestinal endoscopy or surgery.

What does rectal bleeding (blood in stool) mean?

·         Rectal bleeding (known medically as hematochezia) refers to the passage of red blood from the anus, often mixed with stool and/or blood clots. It is called rectal bleeding because the rectum lies immediately above the anus, but red blood in the stool may be coming from the rectum, as discussed later, but it also may be coming from other parts of the gastrointestinal tract.) The severity of rectal bleeding (i.e., the quantity of blood that is passed) varies widely. Most episodes of rectal bleeding are mild and stop on their own. Many patients report only observing a few drops of fresh blood that turns the toilet water pink or observing spots of blood on the tissue paper after they wipe. Others may report brief passage of a spoonful or two of blood. Generally, mild rectal bleeding can be evaluated and treated in the doctor's office without hospitalization or the need for urgent diagnosis and treatment.

Bleeding also may be moderate or severe. Patients with moderate bleeding will repeatedly pass larger quantities of bright or dark red (maroon-colored) blood often mixed with stool and/or blood clots. Patients with severe bleeding may pass several bowel movements or a single bowel movement containing a large amount of blood. Moderate or severe rectal bleeding can quickly deplete a patient's body of blood, leading to symptoms of weakness, dizziness, near-fainting or fainting, signs of low blood pressure or orthostatic hypotension (a drop in blood pressure when going from the sitting or lying position to the standing position). Rarely, the bleeding may be so severe as to cause shock from the loss of blood. Moderate or severe rectal bleeding usually is evaluated and treated in the hospital. Patients with signs and symptoms of a reduced volume of blood often require emergency hospitalization, and transfusion of blood.

Rectal Bleeding (Blood in Stool) Symptoms

Blood in the stool or rectal bleeding is a symptom of a disease or condition.

The color of blood in the stool can be:

• bright red,
• maroon,
• yellow,
• white,
• green,
• black and tarry, or
• not visible to the naked eye (occult).

Causes of blood in stool range from harmless, annoying conditions of the gastrointestinal tract such as hemorrhoids or anal fissures, to serious conditions such as cancer.

What are causes of blood in the stool (rectal bleeding)?

Color of blood in the stool

Blood in the stool primarily comes from the upper gastrointestinal tract (stomach and duodenum although occasionally the esophagus) or the lower gastrointestinal tract (colon, rectum, and anus). Although the small intestine also may be the source of blood in the stool, compared to the upper and lower parts of the gastrointestinal tract, the small intestine is infrequently the source. Most people think of blood in the stool as meaning that the stool contains red blood, but this is not always true. As discussed previously, the bloody stool may be maroon colored or black.

The colon is the part of the gastrointestinal tract through which undigested food passes after the digestible part of the food has been digested and absorbed in the small intestine. The colon is primarily responsible for removing water from the undigested food, and storing the undigested food until it is eliminated from the body as stool. The rectum is the last 15 cm (6 inches) of the colon. The anal canal, approximately an inch in length, connects the rectum with the anus opening through which stool passes when it is eliminated from the body. Together, the colon, rectum, anal canal, and anus form a long (several feet in length), muscular tube that also is known as the large intestine, large bowel, or the lower gastrointestinal tract.

The colon can be divided further into three regions; the right colon, the transverse colon, and the left colon. The right colon, also known as the ascending colon, is the part of the colon into which undigested food from the small intestine is first deposited. It is furthest from the rectum, anal canal, and anus. The transverse colon forms a bridge between the right and the left colon. The left colon is made up of the descending colon and the sigmoid colon. The sigmoid colon connects the descending colon to the rectum.

The color of blood in the stool often depends primarily on the location of the bleeding in the gastrointestinal tract. Generally, the closer the bleeding site is to the anus, the brighter red the blood will be. Thus, bleeding from the anus, rectum, and the sigmoid colon tends to be bright red, whereas bleeding from the transverse colon and the right colon tends to be dark red or maroon-colored. With bleeding from the upper GI tract and depending on how long the blood remains in the stomach and small intestine, the color in the stool will change from bright red, to maroon, to black. Blood in the stool that is red or maroon is most commonly is referred to as rectal bleeding.

Bleeding that occurs from the stomach and duodenum frequently is black, "tarry" (sticky), and foul smelling. The black, smelly and tarry stool is called melena. Melenamostly occurs when the bleeding is in the stomach where the blood is exposed to acid or is in the small intestine for a prolonged amount of time; however, melena also may occur with bleeding from the colon if the transit of the blood through the colon is slow, and there is enough time for the intestinal bacteria to break the blood down into chemicals (hematin) that are black.

Blood from the sigmoid colon, rectum and anus usually does not stay in the colon long enough for the bacteria to turn it black. Rarely, massive bleeding from the right colon, from the small intestine, or from ulcers of the stomach or duodenum can cause rapid transit of the blood through the gastrointestinal tract and result in bright red rectal bleeding. In these situations, the blood is moving through the colon so rapidly that there is not enough time for the bacteria to turn the blood darker or black.

Occult gastrointestinal bleeding

Another "type" of blood in the stool is occult blood. Occult gastrointestinal bleeding refers to a slow loss of blood into the upper or lower gastrointestinal tract that does not change the color of the stool or result in the presence of visible bright red blood. Blood in the stool is detected only by testing the stool for blood (fecal occult blood testing) in the laboratory. Occult blood in the stool has many of the same causes as rectal bleeding, and may be associated with the same symptoms as more active bleeding. For example, slow bleeding from ulcers, colon polyps, or cancers can cause small amounts of blood to mix and be lost within the stool. Chronic occult bleeding often is associated with anemia due to the loss of iron along with the blood (iron deficiency anemia).

Picture of Colon Anatomy and Sources of Rectal Bleeding