Flexible sigmoidoscopy enables the physician to look at the
inside of the large intestine from the rectum through the last part of the
colon, called the sigmoid or descending colon. Physicians may use the procedure
to find the cause of diarrhea, abdominal pain, or constipation. They also use it
to look for early signs of cancer in the descending colon and rectum. With
flexible sigmoidoscopy, the physician can see 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).
For the procedure, you will lie on your left side on the
examining table. The physician will insert a short, flexible, lighted tube into
your rectum and slowly guide it into your 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 your 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, you might feel pressure and slight cramping in your lower abdomen.
You will feel better afterward when the air leaves your colon.
A demonstration of a flexible sigmoidoscope exam.
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 may lie on the left side, in the so called Sim's position, the knee chest position, or on a special proctology table. 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.