Rectal Bleeding (cont.)
Colon cancers and polyps
Tumors of the colon and rectum are growths (masses) arising from the wall
of the large intestine. Benign tumors of the large intestine are called polyps.
Malignant tumors of the large intestine are called cancers, and most are
believed to have developed from polyps. Bleeding from colon polyps and cancers
tends to be mild (the amount of blood loss is small) and intermittent, and
usually does not cause low blood pressure or shock.
Cancers and polyps of the
colon and rectum can cause bright red rectal bleeding, maroon colored stools,
and sometimes melena. The colon cancers and polyps located near the rectum and
the sigmoid colon are more likely to cause mild intermittent bright red rectal
bleeding; while colon cancers located in the right colon are more likely to
cause occult bleeding that over time can lead to moderate or severe iron
deficiency anemia. For more, please see the
Colon Cancer,
Colon Polyps, and
Colon Cancer Screening
articles.
Polypectomy
Colon polyps found during colonoscopy usually are
removed, a process called polypectomy. Bleeding can occur at the site of the
polypectomy days to weeks after the polyp is removed. Such bleeding is called
delayed post-polypectomy bleeding. Smaller polyps (2-3 mm in size) can be
removed with a small biopsy forceps. The amount of blood loss from the use of a
forceps usually is minute, and there will be no delayed bleeding. However,
larger polyps (larger than 5-10 mm) usually are removed with an electro-surgical
snare. These snares are connected to a machine that generates an electrical
current. The polyp is lassoed looped with the snare, and electrical current is
passed through the snare. The electrical current cuts off the polyp and
cauterizes ("heat seals") the tissue at the base of the polyps. Cauterization
prevents bleeding during polypectomy; however, the site of cauterization heals
with the formation of an ulcer. Rarely, these ulcers can bleed several days to
up to 2-3 weeks after polypectomy. Post-polypectomy bleeding can at times be
brisk and severe, and can be bright red, dark red, maroon colored, or black.
Next: Angiodysplasias »
- Colonoscopy - Learn about the colonscopy procedure, what it is, why it is performed, preparation, complications, alternatives and the after effects of the screening exam on MedicineNet.com
- Abdominal Pain - Learn about abdominal pain (pain in the stomach / abdomen) including causes, symptoms, how abdominal pain is diagnosed, and how abdominal pain is treated.
- Fecal Occult Blood Test - Read about the fecal occult blood test in which there are two types, chemical and immunologic. Fecal occult blood tests are used to screen for colon cancer and colon polyps.
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