Sigmoidoscopy
Encyclopedia
Sigmoidoscopy From Greek
Sigma - eidos - scopy, to look inside an s-like object, is the minimally invasive medical
examination of the large intestine
from the rectum
through the last part of the colon
. There are two types of sigmoidoscopy, flexible sigmoidoscopy, which uses a flexible endoscope
, and rigid sigmoidoscopy, which uses a rigid device. Flexible sigmoidoscopy is generally the preferred procedure. A sigmoidoscopy is similar to, but not the same as, a colonoscopy
. A sigmoidoscopy only examines up to the sigmoid
, the most distal part of the colon, while colonoscopy examines the whole large bowel.
to look at the inside of the large intestine from the rectum through the last part of the colon, called the sigmoid. Physicians may use the procedure to find the cause of diarrhea
, abdominal pain
, or constipation
. They also use it to look for benign and malignant polyps
, as well as early signs of cancer
in the descending colon and rectum. With flexible sigmoidoscopy, the physician can see intestinal bleeding, inflammation
, abnormal growths, and ulcers
in the descending colon and rectum. Flexible sigmoidoscopy is not sufficient to detect polyps or cancer in the ascending or transverse colon (two-thirds of the colon). 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
.
For the procedure, the patient must lie on his or her left side on the examining table. The physician inserts a short, flexible, lit tube into the rectum and slowly guides it into the colon. The tube is called a sigmoidoscope. The scope transmits an image of the inside of the rectum and colon, so the physician can carefully examine the lining of these organs. The scope also blows air into these organs, which inflates them and helps the physician see better.
If anything unusual is in the rectum or colon, like a polyp or inflamed tissue, the physician can remove a piece of it using instruments inserted into the scope. The physician will send that piece of tissue (biopsy
) to the lab for testing.
Bleeding and puncture of the colon are possible complications of sigmoidoscopy. However, such complications are uncommon.
Flexible sigmoidoscopy takes 10 to 20 minutes. During the procedure, the patient might feel pressure and slight cramping in the lower abdomen, but he or she will feel better afterward when the air leaves the colon.
, gelatin
, strained fruit juice
, water, plain coffee
, plain tea
, or diet soft drink
s. The night before or right before the procedure, the patient receives a laxative
and an enema
, which is a liquid solution that washes out the intestines.
No sedation is required during this procedure as long as the examination does not exceed the level of the splenic flexure
.
For performing the examination, the patient must lie on the left side, in the so called Sim's position
. The bowels are previously emptied with a suppository
and a digital rectal examination is first performed. The sigmoidoscope is lubricated and inserted with obturator in general direction of the navel
. The direction is then changed and the obturaror is removed so that the physician may penetrate further with direct vision. A bellows
is used to insufflate air to distend the rectum. Lateral movements of the sigmoidoscope's tip negotiate the Houston valve
and the recto-sigmoid junction.
In a 2009 Norwegian study results were somewhat inconclusive at seven years. “We found a trend towards reduced mortality from colorectal cancer for both total colorectal cancer mortality (27% reduction) and rectosigmoidal cancer mortality (37%), but this was not statistically significant in intention to screen analysis. Corresponding reductions in mortality among attenders [that is, the people actually screened, instead of just the ones in the group to be screened-- this data set may include selection bias) were 59% and 76%, both statistically significant compared with the control group”. The study saw no detectable difference in all-cause mortality.
A 2010 British study showed sigmoidoscopy reduced "overall colorectal cancer incidence and mortality by 31 percent," and “incidence of cancer in just the lower part of the colon (or distal colon) was reduced by approximately 50 percent for those who underwent screening compared with those in the control group.”
Overall colon-cancer mortality was reduced by 43% (thus preventing one cancer per 200 screenings, and one cancer death per 500 screenings.) The study also showed that the effect was persistent-- a single sigmoidoscopy reduced cancer rates for the length of the 11 year study.
Greeks
The Greeks, also known as the Hellenes , are a nation and ethnic group native to Greece, Cyprus and neighboring regions. They also form a significant diaspora, with Greek communities established around the world....
Sigma - eidos - scopy, to look inside an s-like object, is the minimally invasive medical
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
examination of the large intestine
Intestine
In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...
from the rectum
Rectum
The rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...
through the last part of the colon
Colon (anatomy)
The colon is the last part of the digestive system in most vertebrates; it extracts water and salt from solid wastes before they are eliminated from the body, and is the site in which flora-aided fermentation of unabsorbed material occurs. Unlike the small intestine, the colon does not play a...
. There are two types of sigmoidoscopy, flexible sigmoidoscopy, which uses a flexible endoscope
Endoscopy
Endoscopy means looking inside and typically refers to looking inside the body for medical reasons using an endoscope , an instrument used to examine the interior of a hollow organ or cavity of the body. Unlike most other medical imaging devices, endoscopes are inserted directly into the organ...
, and rigid sigmoidoscopy, which uses a rigid device. Flexible sigmoidoscopy is generally the preferred procedure. A sigmoidoscopy is similar to, but not the same as, a colonoscopy
Colonoscopy
Colonoscopy is the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. It may provide a visual diagnosis and grants the opportunity for biopsy or removal of suspected...
. A sigmoidoscopy only examines up to the sigmoid
Sigmoid colon
The sigmoid colon is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about 40 cm...
, the most distal part of the colon, while colonoscopy examines the whole large bowel.
Flexible sigmoidoscopy
Flexible sigmoidoscopy enables the physicianPhysician
A physician is a health care provider who practices the profession of medicine, which is concerned with promoting, maintaining or restoring human health through the study, diagnosis, and treatment of disease, injury and other physical and mental impairments...
to look at the inside of the large intestine from the rectum through the last part of the colon, called the sigmoid. Physicians may use the procedure to find the cause of diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
, abdominal pain
Abdominal pain
Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem...
, or constipation
Constipation
Constipation refers to bowel movements that are infrequent or hard to pass. Constipation is a common cause of painful defecation...
. They also use it to look for benign and malignant polyps
Colorectal polyp
A colorectal polyp is a polyp occurring on the lining of the colon or rectum. Untreated colorectal polyps can develop into colorectal cancer....
, as well as early signs of cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
in the descending colon and rectum. With flexible sigmoidoscopy, the physician can see intestinal bleeding, inflammation
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
, abnormal growths, and ulcers
Peptic ulcer
A peptic ulcer, also known as PUD or peptic ulcer disease, is the most common ulcer of an area of the gastrointestinal tract that is usually acidic and thus extremely painful. It is defined as mucosal erosions equal to or greater than 0.5 cm...
in the descending colon and rectum. Flexible sigmoidoscopy is not sufficient to detect polyps or cancer in the ascending or transverse colon (two-thirds of the colon). 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
Colorectal cancer
Colorectal cancer, commonly known as bowel cancer, is a cancer caused by uncontrolled cell growth , in the colon, rectum, or vermiform appendix. Colorectal cancer is clinically distinct from anal cancer, which affects the anus....
, for example the rectum
Rectum
The rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...
.
For the procedure, the patient must lie on his or her left side on the examining table. The physician inserts a short, flexible, lit tube into the rectum and slowly guides it into the colon. The tube is called a sigmoidoscope. The scope transmits an image of the inside of the rectum and colon, so the physician can carefully examine the lining of these organs. The scope also blows air into these organs, which inflates them and helps the physician see better.
If anything unusual is in the rectum or colon, like a polyp or inflamed tissue, the physician can remove a piece of it using instruments inserted into the scope. The physician will send that piece of tissue (biopsy
Biopsy
A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...
) to the lab for testing.
Bleeding and puncture of the colon are possible complications of sigmoidoscopy. However, such complications are uncommon.
Flexible sigmoidoscopy takes 10 to 20 minutes. During the procedure, the patient might feel pressure and slight cramping in the lower abdomen, but he or she will feel better afterward when the air leaves the colon.
Preparation
The colon and rectum must be completely empty for flexible sigmoidoscopy to be thorough and safe, thus the patient must drink only clear liquids for 12 to 24 hours beforehand. This includes bouillon or brothBroth
Broth is a liquid food preparation, typically consisting of either water or an already flavored stock, in which bones, meat, fish, cereal grains, or vegetables have been simmered. Broth is used as a basis for other edible liquids such as soup, gravy, or sauce. It can be eaten alone or with garnish...
, gelatin
Gelatin
Gelatin is a translucent, colorless, brittle , flavorless solid substance, derived from the collagen inside animals' skin and bones. It is commonly used as a gelling agent in food, pharmaceuticals, photography, and cosmetic manufacturing. Substances containing gelatin or functioning in a similar...
, strained fruit juice
Juice
Juice is the liquid that is naturally contained in fruit or vegetable tissue.Juice is prepared by mechanically squeezing or macerating fruit or vegetable flesh without the application of heat or solvents. For example, orange juice is the liquid extract of the fruit of the orange tree...
, water, plain coffee
Coffee
Coffee is a brewed beverage with a dark,init brooo acidic flavor prepared from the roasted seeds of the coffee plant, colloquially called coffee beans. The beans are found in coffee cherries, which grow on trees cultivated in over 70 countries, primarily in equatorial Latin America, Southeast Asia,...
, plain tea
Tea
Tea is an aromatic beverage prepared by adding cured leaves of the Camellia sinensis plant to hot water. The term also refers to the plant itself. After water, tea is the most widely consumed beverage in the world...
, or diet soft drink
Soft drink
A soft drink is a non-alcoholic beverage that typically contains water , a sweetener, and a flavoring agent...
s. The night before or right before the procedure, the patient receives a laxative
Laxative
Laxatives are foods, compounds, or drugs taken to induce bowel movements or to loosen the stool, most often taken to treat constipation. Certain stimulant, lubricant, and saline laxatives are used to evacuate the colon for rectal and/or bowel examinations, and may be supplemented by enemas under...
and an enema
Enema
An enema is the procedure of introducing liquids into the rectum and colon via the anus. The increasing volume of the liquid causes rapid expansion of the lower intestinal tract, often resulting in very uncomfortable bloating, cramping, powerful peristalsis, a feeling of extreme urgency and...
, which is a liquid solution that washes out the intestines.
No sedation is required during this procedure as long as the examination does not exceed the level of the splenic flexure
Splenic flexure
The splenic flexure is a sharp bend between the transverse and the descending colon in the left upper quadrant of humans. The left colic flexure is near the spleen, and hence called the splenic flexure. There are two colic flexures in the transverse colon — the other being the hepatic...
.
Rigid sigmoidoscopy
Rigid sigmoidoscopy no longer has the value it had in the past, before the advent of videocolonoscopy (flexible sigmoidoscopy). However, it may be still useful in ano-rectal diseases such as bleeding per rectum or inflammatory rectal disease, particularly in the general practice and pediatrics.For performing the examination, the patient must lie on the left side, in the so called Sim's position
Sim's position
The Sims' position, named after James Marion Sims is usually used for rectal examination, treatments and enemas. It is performed by having a patient lie on their left side, left hip and lower extremity straight, and right hip and knee bent....
. The bowels are previously emptied with a suppository
Suppository
A suppository is a drug delivery system that is inserted into the rectum , vagina or urethra , where it dissolves.They are used to deliver both systemically-acting and locally-acting medications....
and a digital rectal examination is first performed. The sigmoidoscope is lubricated and inserted with obturator in general direction of the navel
Navel
The navel is a scar on the abdomen caused when the umbilical cord is removed from a newborn baby...
. The direction is then changed and the obturaror is removed so that the physician may penetrate further with direct vision. A bellows
Bellows
A bellows is a device for delivering pressurized air in a controlled quantity to a controlled location.Basically, a bellows is a deformable container which has an outlet nozzle. When the volume of the bellows is decreased, the air escapes through the outlet...
is used to insufflate air to distend the rectum. Lateral movements of the sigmoidoscope's tip negotiate the Houston valve
Houston valve
Houston's valves are semi-lunar transverse folds of the rectal wall that protrude into the rectum, not the anal canal as that lies below the rectum. Their use seems to be to support the weight of fecal matter, and prevent its urging toward the anus, which would produce a strong urge to defecate...
and the recto-sigmoid junction.
Benefits of Sigmoidoscopy
Several studies have shown the benefits of sigmoidoscopy in detecting colorectal cancer.In a 2009 Norwegian study results were somewhat inconclusive at seven years. “We found a trend towards reduced mortality from colorectal cancer for both total colorectal cancer mortality (27% reduction) and rectosigmoidal cancer mortality (37%), but this was not statistically significant in intention to screen analysis. Corresponding reductions in mortality among attenders [that is, the people actually screened, instead of just the ones in the group to be screened-- this data set may include selection bias) were 59% and 76%, both statistically significant compared with the control group”. The study saw no detectable difference in all-cause mortality.
A 2010 British study showed sigmoidoscopy reduced "overall colorectal cancer incidence and mortality by 31 percent," and “incidence of cancer in just the lower part of the colon (or distal colon) was reduced by approximately 50 percent for those who underwent screening compared with those in the control group.”
Overall colon-cancer mortality was reduced by 43% (thus preventing one cancer per 200 screenings, and one cancer death per 500 screenings.) The study also showed that the effect was persistent-- a single sigmoidoscopy reduced cancer rates for the length of the 11 year study.
Risks
Although generally considered quite safe, sigmoidoscopy does carry the very rare possibility of tearing of the intestinal wall by the instrument, which would require immediate surgery to repair the tear; in addition, removal of a polyp may sometimes lead to localized bleeding which is resistant to cauterization by the instrument and must be stopped by surgical intervention.Sources
- Flexible Sigmoidoscopy. National Digestive Diseases Information Clearinghouse. National Institute for Digestive and Kidney Diseases. Public domain text used as source for this article.
- Rigid Sigmoidoscopy. The Wales Day Centre.
External links
- Sigmoidoscopy Patient Experiences
- Flexible Sigmoidoscopy - NIHNational Institute of Diabetes and Digestive and Kidney DiseasesThe National Institute of Diabetes and Digestive and Kidney Diseases , of the U.S. National Institutes of Health, conducts and supports research on many of the most serious diseases affecting public health...