There are various types of polyps that can be found in the large bowel. The most
common type of colon polyp is the adenoma which is a benign tumor (premalignant)
that has the potential to develop into an invasive cancer if left in place and allowed
to grow for years. Very rarely, polyps are found that have already developed into
small cancers; these are called polyp cancers. Some polyps have begun the transformation
to cancer; in this situation, microscopically, the polyp cells more closely resemble
a cancer than an adenoma yet there is no invasion beyond the innermost layer of
the colon wall. These are given the name dysplastic polyps or “carcinoma in situ”.
The second most common type of polyp, usually quite small, is called a hyperplastic
polyp. Although hyperplastic polyps arise in the colon they are more often found
in the rectum. Thankfully, hyperplastic polyps are not capable of transforming into
a cancer. A third category of polyps, inflammatory, are found in patients who have
had colitis related to inflammatory bowel disease, or infection. Thankfully, these
polyps do not have the capacity to turn into a cancer.
Polyps come in a variety of shapes and sizes. Some are flat and grow directly on
the surface of the colon while others are like small mushrooms that protrude into
the colon on thin flexible stalks. Adenomas range in size from several millimeters
(1/16 of an inch) to over 10 cm (3 inches). The chances that a given adenoma polyp
may contain an invasive cancer is related to the size of polyp and to the type of
adenoma that is present.
It is usually not possible to distinguish between adenomas (which can turn into
a cancer) and the other types of polyps just by looking at them. Therefore, when
polyps are found they are removed or at least biopsied. Most polyps are small enough
that they can be removed or destroyed at the time of colonoscopy. A small percentage
of polyps are too large to be removed with the colonoscope. These larger polyps
are removed in the operating room by resecting a portion or segment of the colon
or through a combined laparoscopic and colonoscopic method.
The great majority of benign colon and rectal polyps are small or moderate sized
and can be removed through the colonoscope in the outpatient setting using a variety
of instruments that are passed through a narrow channel in the colonoscope. Very
small polyps are destroyed with a forceps that grasps and removes small pieces of
the rectal lining. Larger polyps are removed most often with a metal snare (like
a noose) that is passed through a thin insulated hollow plastic tube. The snare
and plastic sheath are passed through a channel in the colonoscope to the scopes
tip and beyond. The snare is placed around the polyp (often shaped like a mushroom)
and tightened while electric current is passed through the wire. This cauterizes
the stalk of the polyp while it is being cut. If possible, the polyp is recovered
and sent for pathological analysis. Polyps can also be directly burned or cauterized
with heat or electric current, usually after one or several biopsies have been obtained.
Larger polyps, especially the flat ones, are more difficult to treat colonoscopically.
Ideally, a polyp is removed completely and intact with a single application of the
wire snare. However, this is not possible for some middle sized and larger polyps.
One approach to these lesions is to remove them in pieces using the wire snare multiple
times. To make it easier and safer to remove these larger polyps saline or other
solutions are sometimes injected into the bowel wall via a catheter (with a needle
at its tip) which is passed through the colonoscope. The injected fluid expands
and swells the bowel wall making it thicker which protects the deeper muscle layers
of the bowel wall from injury when the snare is used to remove parts of the polyp.
In some cases it is not possible to fully remove the polyp at one colonoscopy. In
this situation it is common to mark or “tattoo” the location of the polyp with India
ink or another dye so that the area can be easily found. The colonoscopy is usually
repeated months later at which time an attempt is made to remove the remaining polyp,
usually with a metal snare, as before. It may take 3 or 4 colonoscopies to fully
destroy a larger polyp using the colonoscope.
Unfortunately, when some polyps are initially found they are judged too large to
be removed with a colonoscope in an endoscopy suite. Also, in some patients, after
several attempts to colonoscopically remove a polyp, the gastroenterologist will
make the judgement that the polyp can be fully destroyed with the scope. In these
situations the patient is usually referred to a surgeon after the polyp has been
tattooed with India ink.
Historically, a segmental “cancer type” bowel resection is carried out to remove
adenomas of the colon that are judged not amenable to removal with a colonoscope.
In this case a 7 to 10 inch length of colon is resected (the polyp is usually in
the middle of the specimen) along with the lymph nodes and blood vessels supplying
the bowel after which the remaining ends are rejoined. Many patients ask why so
much bowel is removed to treat a benign polyp? The reason is that 10 to 15 percent
of large, supposedly benign, polyps that come to surgical resection are found to
contain invasive cancers. Certainly, for the 10-15 percent of patients with cancers
the lengthier and more extensive resection is logical and appropriate. In regards
to the remaining 85-90 percent of patients with benign polyps the cancer type resection
is not necessary. If there were a way to be reasonably certain that a polyp was,
in fact, benign, then, perhaps, the radical resection could be avoided.
An important method of judging a polyp is by taking multiple biopsies of it through
the colonoscope. Another useful method is to inject saline into the bowel wall beneath
the polyp to see if the polyp “lifts” off the deeper layers of the bowel wall. The
injected fluid greatly expands the middle layer of the bowel wall that separates
the inner lining from the outer muscle coating of the colon. If the polyp rises,
then the lesion is not invading into the muscular layer (a characteristic of invasive
cancers). This saline lift test is easily done through the colonoscope. Yet another
method is endoscopic ultrasound which uses sound waves to determine whether the
polyp is invading and into the deeper bowel wall layers. Simply taking a close look
at a polyp can also provide important information to the surgeon. What are the alternatives
to a full segmental cancer type resection for polyps judged benign by the above
Some large benign polyps can be removed by resecting a small oval shaped piece of
the bowel wall (part of the circumference only) that includes the polyp and a small
rim of normal bowel wall. This is called a "wedge" resection. This operation avoids
extensive dissection and does not include division of the blood vessels supplying
the area or removal of the lymph nodes. In short, it is a much smaller and less
radical operation that requires minimal dissection of the colon and removes far
less tissue. The chances of having a complication after this type of surgery are
lower because less has been done. Patients usually go home in 1 to 2 days as opposed
to 3 to 5 days after the standard cancer type bowel resection.
The “wedge” resection is best performed laparoscopically. Using this method the
polyp and adjacent bowel wall is resected with a narrow stapler that is inserted
through a hollow 1 inch "port" in the abdominal wall. The specimen is removed through
one of the laparoscopic port wounds in a plastic bag after which a pathologist immediately
examines the polyp and carries out one or several "frozen sections" to verify that
the lesion is an adenoma only. The patient remains on the operating room table asleep
while the polyp is evaluated. In the unlikely situation that the frozen section
reveals an invasive cancer, then a standard cancer type resection would be immediately
carried out laparoscopically.
Another way to remove some of these polyps is to perform a colonoscopy in conjunction
with laparoscopy in the operating room with the patient under general anesthesia.
The laparoscopic instruments can be used to push on the outside of the colon wall
to make it easier for the doctor driving the colonoscope to grasp the polyp with
a snare. In this way, some polyps that could not be removed during a regular outpatient
colonoscopy can be excised. It is also possible to use advanced colonoscopic polypectomy
methods to remove these polyps. One such method is called ESD or Endoscopic Submucosal
Dissection. In this method a thin wire connected to an electric cautery machine
is passed through an insulated sheath through the colonoscope and used to make an
incision around the polyp (like a knife). Then other colonoscopic tools are used
to lift and dissect beneath the polyp in order to fully detach it. If successful,
at the end, the polyp has been removed in one piece and the underlying muscle layer
remains intact. If successful, this method avoids removing even a “wedge” of the
entire bowel wall.
My approach is to assess all patients with large benign polyps who are sent for
a standard colon resection and determine if either the laparoscopic "wedge" or the
combined laparoscopic / colonoscopic polypectomy methods can be utilized. The goal
is to remove the polyp via the least invasive method possible. If successful, patients
are home sooner with all or more of their colon in tact. Because it is not possible
to be certain before surgery that a polyp can be removed via a combined laparoscopic/colonoscopic
or wedge method, patients must consent to a standard colectomy in addition to the
less invasive polyp removal methods. The consent states that, at the end of the
procedure, the polyp will have been removed by one of the 3 methods with the standard
cancer type resection being the last resort.
When the colonoscopy is performed in the operating room on the day of surgery if
the polyp lifts when injected and is judged resectable via colonoscope then an attempt
will be made to excise it using a variety of colonoscopic tools. If needed, the
polyp can be manipulated externally with laparoscopic instruments to facilitate
removal. If the polyp is successfully removed a test is done to make sure that the
colon wall is not perforated after which the scopes are removed and the patient
If it is not possible to fully remove the polyp using colonoscopic methods, the
borders of the polyp are marked with india ink and then an attempt is made to do
a laparoscopic wedge resection of the polyp and the adjacent colon wall with a stapler.
The colonoscope, still in place, views the placement of the stapler to male sure
all is well. If successful, then the specimen is put in a plastic bag and removed
through one of the small wounds. However, if the polyp will not lift when injected,
is judged too large for colonoscopic or wedge resection, or looks like a cancer
then the standard cancer type bowel resection would be immediately performed.
Our family wishes to express our heartfelt appreciation for the kindness, excellent
care and wisdom our mother, Jean Broussard, received during her hospitalization.