In the lower digestive tract, the large intestine and rectum are frequent sites of bleeding. Inflammation from various causes can contribute to produce extensive bleeding from the colon. Different intestinal infections can cause inflammation and bloody diarrhoea as well. Ulcerative colitis can produce inflammation and extensive surface bleeding from tiny ulcerations. Crohn's disease of the large intestine can also produce bleeding. Diverticular disease caused by Diverticular outpouching of the colon wall can result in massive bleeding. Finally, as one gets older, abnormalities may develop in the blood vessels of the large intestine, which may result in recurrent rectal bleeding.
Causes of Rectal Bleeding include:
Haemorrhoids, anal fissure, infection, inflammation (ulcerative colitis), colorectal polyps, colon cancer and diverticular disease.
Haemorrhoids are the most common cause of visible blood especially blood that appears bright red. Haemorrhoids are enlarged veins in the anal area that can rupture and produce bright red blood, which can show up in the toilet or on toilet paper. If red blood is seen, however, it is essential to exclude other causes of bleeding since the anorectal area may also be the site of cuts (fissures), inflammation, or cancer.
Benign growths or polyps of the colon are very common and are thought to be forerunners of cancer. These growths can cause either bright red blood or occult bleeding. Colon cancer is the most frequently diagnosed cancer in Australia and often causes occult bleeding at some time, but not necessarily visible bleeding. The signs of bleeding in the digestive tract depend upon the site and severity of bleeding. If blood is coming from the rectum or the lower colon, bright red blood will coat or mix with the stool. The stool may be mixed with darker blood if the bleeding is higher up in the colon or at the far end of the small intestine. If sudden massive bleeding occurs, a person may experience feelings of weakness, dizziness, faintness, shortness of breath, and cramping abdominal pain or diarrhoea. Shock may occur, with a rapid pulse, drop in blood pressure, and difficulty in producing urine. The patient may become very pale. If bleeding is slow and occurs over a long period of time, a gradual onset of fatigue, lethargy, shortness of breath and pallor from the anaemia will result. Anaemia is a condition in which the blood's iron-rich substance, haemoglobin, is diminished.
Other associated symptoms include changes in bowel habit, stool colour (to black or red) and the consistency of stool, and the presence of pain or tenderness in the bowel.
Clinical Recognition and Diagnosis
When diagnosing rectal bleeding, the site of the bleeding must be located if possible. A complete history and physical examination are essential. Symptoms such as changes in bowel habits, stool colour (to black or red) and consistency, and the presence of pain or tenderness may tell the doctor which area of the Gastro Intestinal tract is affected. Because the intake of iron, bismuth or foods such as beetroot can give the stool the same appearance as bleeding from the digestive tract, it is an advantage to test the stool for blood at first before offering a diagnosis. A blood count will indicate whether the patient is anaemic and also will give an idea of the extent of the bleeding and how chronic it has been.
Gastroenterologists also perform colonoscopy procedures, which allow the specialist to accurately detect and examine the area of the large intestine that is bleeding. Because the endoscope can detect lesions and confirm the presence or absence of bleeding, Gastroenterologists often choose this method to diagnose patients with acute bleeding. In many cases, the doctor can also use the endoscope to treat the cause of bleeding as well.
Colonoscopy is a procedure which allows the Gastroenterologist to view the colon and rectum, collect small samples of tissue (biopsies), and to take photographs for later reference.
Colonoscopy is the primary diagnostic and therapeutic procedure for most causes of gastro intestinal bleeding. Removal of polyps with an endoscope can control bleeding from colon polyps. Removal of haemorrhoids by banding or various heat or electrical devices (such as infra-red coagulation or IRC) is effective in patients who suffer haemorrhoidal bleeding on a recurrent basis. Endoscopic injection or cautery can be used to treat bleeding sites throughout the lower intestinal tract. Although endoscopy techniques effectively treat most cases of rectal bleeding, there are rare cases of this treatment not being sufficient. In these cases, angiography can be applied, and possibly surgery to control active, severe or recurrent bleeding when colonoscopies are unsuccessful.
A fissure is a split in the anal sphincter which may bleed and hurt as if a razor blade is being passed during stool. It is treated firstly by softening the stool and more commonly in the chronic fissures by injection of a muscle relaxant under sedation. Surgery is mostly avoided and is avoidable as it may, many years later, lead to incontinence.