A report on Colorectal cancerColonoscopy and Rectum

Location and appearance of two example colorectal tumors
Colonoscopy being performed
Scheme of digestive tract, with rectum marked
Longitudinally opened freshly resected colon segment showing a cancer and four polyps. Plus a schematic diagram indicating a likely field defect (a region of tissue that precedes and predisposes to the development of cancer) in this colon segment. The diagram indicates sub-clones and sub-sub-clones that were precursors to the tumors.
A container of PEG (polyethylene glycol or macrogol) with electrolyte used to clean out the intestines before certain bowel exam procedures such as a colonoscopy.
The inside of a normal human rectum in a 70-year-old, seen during colonoscopy
Colon cancer with extensive metastases to the liver
Schematic overview of colonoscopy procedure
Retroflexed view of the human rectum seen at colonoscopy showing anal verge
Relative incidence of various histopathological types of colorectal cancer. The vast majority of colorectal cancers are adenocarcinomas.
Polyp is identified.
A digital rectal exam is conducted to investigate or diagnose conditions including of the prostate.
Micrograph of colorectal adenocarcinoma, showing "dirty necrosis".
A sterile solution is injected under the polyp to lift it away from deeper tissues.
Arteries of the pelvis
A diagram of a local resection of early stage colon cancer
A portion of the polyp is now removed.
Blood vessels of the rectum and anus
A diagram of local surgery for rectal cancer
The polyp is fully removed.
Cross-section microscopic shot of the rectal wall
Colon and rectum cancer deaths per million persons in 2012
Dog rectum cross-section (40×)
Microscopic cross-section of the rectum of a dog (400×), showing a high concentration of goblet cells in amongst the column-shaped lining. Goblet cells can be seen as the circular cells with a clear inner material (cytoplasm).

Colorectal cancer (CRC), also known as bowel cancer, colon cancer, or rectal cancer, is the development of cancer from the colon or rectum (parts of the large intestine).

- Colorectal cancer

It can provide a visual diagnosis (e.g., ulceration, polyps) and grants the opportunity for biopsy or removal of suspected colorectal cancer lesions.

- Colonoscopy

Colorectal cancer may be diagnosed by obtaining a sample of the colon during a sigmoidoscopy or colonoscopy.

- Colorectal cancer

Colonoscopy and sigmoidoscopy are forms of endoscopy that use a guided camera to directly view the rectum.

- Rectum

Rectal cancer, a subgroup of colorectal cancer specific to the rectum.

- Rectum

The endoscope is then passed through the anus up the rectum, the colon (sigmoid, descending, transverse and ascending colon, the cecum), and ultimately the terminal ileum.

- Colonoscopy
Location and appearance of two example colorectal tumors

3 related topics with Alpha


Front of abdomen, showing the large intestine, with the stomach and small intestine in gray.

Large intestine

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Last part of the gastrointestinal tract and of the digestive system in vertebrates.

Last part of the gastrointestinal tract and of the digestive system in vertebrates.

Front of abdomen, showing the large intestine, with the stomach and small intestine in gray.
Illustration of the large intestine.
Inner diameters of colon sections
Colonic crypts (intestinal glands) within four tissue sections. The cells have been stained to show a brown-orange color if the cells produce the mitochondrial protein cytochrome c oxidase subunit I (CCOI), and the nuclei of the cells (located at the outer edges of the cells lining the walls of the crypts) are stained blue-gray with haematoxylin. Panels A, B were cut across the long axes of the crypts and panels C, D were cut parallel to the long axes of the crypts. In panel A the bar shows 100 µm and allows an estimate of the frequency of crypts in the colonic epithelium. Panel B includes three crypts in cross-section, each with one segment deficient for CCOI expression and at least one crypt, on the right side, undergoing fission into two crypts. Panel C shows, on the left side, a crypt fissioning into two crypts. Panel D shows typical small clusters of two and three CCOI deficient crypts (the bar shows 50 µm). The images were made from original photomicrographs, but panels A, B and D were also included in an article and illustrations were published with Creative Commons Attribution-Noncommercial License allowing re-use.
Histological section.
Colonoscopy image, splenic flexure,
normal mucosa. You can see spleen through it : the black part
Micrograph of normal large instestinal crypts.
Anatomy of normal large intestinal crypts
Colon. Deep dissection. Anterior view.

Water is absorbed here and the remaining waste material is stored in the rectum as feces before being removed by defecation.

A significant indirect health consequence is that use of a standard adult colonoscope is difficult and in some cases impossible when a redundant colon is present, though specialized variants on the instrument (including the pediatric variant) are useful in overcoming this problem.

Bacteroides are implicated in the initiation of colitis and colon cancer.


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Sigmoidoscopy (from the Greek term for letter "s/ς" + "eidos" + "scopy": namely, to look inside an "s"/"ς"-like object) is the minimally invasive medical examination of the large intestine from the rectum through to the nearest part of the colon, the sigmoid colon.

A sigmoidoscopy is similar to, but not the same as, a colonoscopy.

However, although in absolute terms only a relatively small section of the large intestine can be examined using sigmoidoscopy, the sites which can be observed represent areas which are most frequently affected by diseases such as colorectal cancer, for example the rectum.

Endoscopic image of a colon affected by ulcerative colitis. The internal surface of the colon is blotchy and broken in places. Mild-moderate disease.

Ulcerative colitis

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Endoscopic image of a colon affected by ulcerative colitis. The internal surface of the colon is blotchy and broken in places. Mild-moderate disease.
Classification of colitis, often used in defining the extent of involvement of ulcerative colitis, with proctitis (blue), proctosigmoiditis (yellow), left sided colitis (orange) and pancolitis (red). All classes extend distally to the end of the rectum.
Gross pathology of normal colon (left) and severe ulcerative colitis (right), forming pseudopolyps (smaller than the cobblestoning typically seen in Crohn's disease), over a continuous area (rather than skip lesions of Crohn's disease), and with a relatively gradual transition from normal colon (while Crohn's is typically more abrupt).
Aphthous ulcers involving the tongue, lips, palate, and pharynx.
Pyoderma gangrenosum with large ulcerations affecting the back.
Endoscopic image of ulcerative colitis affecting the left side of the colon. The image shows confluent superficial ulceration and loss of mucosal architecture. Crohn's disease may be similar in appearance, a fact that can make diagnosing UC a challenge.
H&E stain of a colonic biopsy showing a crypt abscess, a classic finding in ulcerative colitis
Colonic pseudopolyps of a person with intractable UC, colectomy specimen
Biopsy sample (H&E stain) that demonstrates marked lymphocytic infiltration (blue/purple) of the intestinal mucosa and architectural distortion of the crypts.

Ulcerative colitis (UC) is a long-term condition that results in inflammation and ulcers of the colon and rectum.

Complications may include abnormal dilation of the colon (megacolon), inflammation of the eye, joints, or liver, and colon cancer.

Diagnosis is typically by colonoscopy with tissue biopsies.