| Flexible Sigmoidoscopy
 Sigmoidoscopy
is the visual examination of the inside of the rectum and sigmoid colon, using a
lighted, flexible tube connected to an eyepiece or video screen for viewing.
This device is called an endoscope. The colon (large intestine) is 5 to 6 feet
long. During a sigmoidoscopy, only the last 1 to 2 feet of the colon is
examined. This last part of the colon, just above the rectum, is called the
sigmoid colon.
Equipment
The flexible endoscope is a remarkable piece of equipment that can be directed
and moved around the bends in the lower colon and rectum. The image in the bowel
is transmitted through the endoscope either to the eyepiece or a video screen.
An open channel in the scope allows other instruments to be passed through it to
take tissue samples (biopsies) or to remove polyps. 
Reasons for the Exam
Sigmoidoscopy is performed to diagnose the cause of certain symptoms. It is also
used as a preventative measure to detect problems at an early stage, even before
the patient recognizes symptoms. The following are some reasons for performing a
sigmoidoscopy.
Bleeding -- Rectal bleeding is very common. It often is caused by
hemorrhoids or by a small tear at the anus, called a fissure. However, more
serious problems can cause bleeding. Benign polyps can bleed. It is important
to identify and remove polyps at an early stage before they can become
cancerous. Rectal and colon cancers bleed and require immediate diagnosis and
treatment. Finally, various forms of colitis and inflammation can cause
bleeding.
Diarrhea -- Persistent diarrhea should always be evaluated. There
are many causes of diarrhea and the exam is of great help in tracking down the
specific cause.
Pain -- Hemorrhoids and fissures are some causes of pain around the
anus or in the rectum. Discomfort in the lower abdomen can be caused by
tumors. Diverticulosis can occur in the lower bowel. With this condition,
small pockets or sacks project from the bowel.
X-ray Findings -- A barium enema x-ray exam may show abnormalities
that need to be confirmed or treated by sigmoidoscopy.
Detection -- Colon cancer is one of the most common cancers in the
country. It is highly curable if it is found early. This cancer usually begins
in the colon as a polyp that remains benign for many years. Therefore, it is
generally advisable to have a sigmoidoscopy after age 40 or 50. If parents,
brothers, or sisters have had colon polyps or colon cancer, it is even more
critical to have this exam. The tendency to develop colon cancer and polyps
can be inherited.
Preparation for the Test
To obtain the full benefit of the exam and allow a thorough inspection, the
rectum and sigmoid colon must be clean. Preparation usually involves drinking
clear liquids the day before along with taking enemas and/or laxatives. Specific
instructions for preparation are provided beforehand. 
The Procedure
Flexible sigmoidoscopy is usually performed on an outpatient basis. It is
performed with the patient lying on the left side with the legs drawn up. A
sheet is placed over the lower body. A finger or digital exam of the anus and
rectum is performed. Then the endoscope is gently inserted into the rectum. Air
is inflated into the bowel to expand it and allow for careful examination. The
patient usually feels a slight discomfort similar to strong gas cramps. The
endoscope is then advanced under direct vision and moved around the various
bends in the lower bowel.
It is advanced as far as possible without causing undue discomfort. When
possible, the exam is continued to 25 inches (60 cm). Certain conditions, such
as diverticulosis, irritable bowel syndrome, or prior pelvic surgery may produce
discomfort when the sigmoid colon is entered by the endoscope. The exam is
stopped if this occurs. The exam usually takes 5 to 15 minutes. Sedation is not
normally required.
Benefits
The benefits of sigmoidoscopy can include the following:
 | It is often possible to determine the specific cause of symptoms.
| Conditions such as colitis and diverticulosis can be monitored to
determine effectiveness of treatment.
| Polyps and tumors can be discovered at an early stage. |
| |
Alternative Testing
Alternative testing includes barium enema x-ray exams. Additionally, the stools
can be examined in a variety of ways to uncover or study certain bowel
conditions. However, a direct look at the lower rectum and lower bowel by
sigmoidoscopy is by far the best method of examining this area.
Side Effects and Risks
Bloating and bowel distension are common due to the air inflated into the bowel.
This usually lasts only 30 to 60 minutes. If biopsies are done or if a polyp is
removed, there may be some spotting of blood. However, this is rarely serious.
Other uncommon risks include a diagnostic error or oversight, or a tear
(perforation) of the wall of the colon which might require surgery.
Summary
Sigmoidoscopy is a simple outpatient exam which can uncover a serious medical
problem. Specific diagnoses can be made. Treatment programs can be evaluated, or
reassurance can be provided when the exam is normal. It is one of the most
useful and simple exams in medicine.
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