Endosonography
of the Anal Canal in the Evaluation of Fecal Incontinence
Endoluminal
sonography of the rectum has been utilized in the last ten years as an
adjunct modality in the evaluation and staging of rectal cancer. With
experience, it became evident that excellent imaging of the individual
muscles of the anal canal and pelvic floor can be achieved. Surgeons
skilled in the evaluation of fecal incontinence realize the physical
examination with digital rectal examination is often equivocal in the
ability to identify a sphincter defect. Disruption or thinning of the
sphincter mechanism is however readily appreciated with this quick and
painless examination.
Endoanal sonography
relies on an image is created by a rotating piezoelectric crystal
transducer probe which is placed into the anal canal. The crystal both
sends and receives ultrasound (10 MHz) frequency waves, with different
tissues (i.e. smooth muscle, fat, mucosa, bone) allowing different
degrees of reflection and transmission according to their intrinsic
acoustic density. A real time ultrasound image is generated based upon
the reflected waves received by the rotating transducer probe.
The accuracy of the
endoanal ultrasound examination is quite surprising. It correlates
very well with structural findings noted at surgical exploration. The
exam permits detailed investigation of the internal and external
sphincter for areas of thinning or disruption, as well as other
structures of the pelvic floor such as puborectalis muscle, urethral
sphincter, vagina, and outlines of the bony pelvis. The examination
has proven to be quite accurate in the evaluation of obstetrical
injury to the sphincter, and can reliably identify sphincter injuries
amenable to surgical correction. Endoanal sonography has now emerged
as the procedure of choice to evaluate anal sphincter anatomy and
continuity during the evaluation of fecal incontinence.
Preoperative
Radiotherapy for Rectal Cancer
Sphincter saving
surgery is increasingly common in the treatment of cancers of the low
and middle rectum. These operations can be performed with the same
prospects for cure as removal of the rectum and colostomy as long as
lateral and lower margins are free of disease. Postoperative
radiotherapy is commonly recommended for rectal cancers if the
circular muscle coat is breached by tumor or lymph nodes are involved.
Postoperative radiotherapy after bowel resection and anastomosis can
however affect functional results. Patients often complain of rectal
urgency, incontinence, and soiling that leads to some degree of
impaired social life. Small bowel radiation injury is also common when
postoperative radiotherapy is used since small bowel adhesions to the
pelvic structures fix the small bowel in place (maximizing damage).
Preoperative
radiotherapy offers obvious advantages, since the majority of the
irradiated bowel is removed at surgery and nonirradiated bowel is
delivered into the pelvis for anastomosis. The nonirradiated bowel
maintains near normal compliance, and when combined with a colonic
reservoir J-pouch (see below) can decrease urgency and stool frequency
to a substantial degree. Preoperative radiotherapy also has potential
to downstage rectal tumors and make sphincter saving surgery possible.
In addition, small bowel radiation injury is minimized since surgical
adhesions do not fix the small bowel in place.
In the past,
preoperative radiotherapy was only offered at research institutions,
since radiation oncology physicians were reluctant to give
radiotherapy treatment prior to accurate staging, which generally
required surgical resection and pathologic analysis. In addition,
there was only weak scientific evidence that preoperative radiotherapy
prolonged survival. The recent Swedish Rectal Cancer Trial (1997)
demonstrates statistically significant reduction in local cancer
failure rates and an improvement in overall survival by using
high-dose preoperative radiotherapy. Our ability to accurately stage
these rectal cancers prior to treatment has improved as well; imaging
studies with endorectal ultrasound, CT, and MRI scans give excellent
anatomic information about the depth of tumor penetration and lymph
node involvement. Because of vastly improved functional results,
improved tumor resectability, and diminished long term sequelae, we
embrace the philosophy of preoperative radiotherapy for middle and low
rectal cancers.
Colonic
Reservoir (Colon J-Pouch) Reconstruction after Rectal Cancer Surgery
The
functional outcome of patients after anterior resection of the
rectosigmoid is often less than optimal. Patients may complain of
urgency, incontinence, and stool soiling which can greatly impact
social life. Some authors refer to this diminished function as the
"anterior resection syndrome." Why this affects some more
than others is not clearly understood, but we know that reservoir
function of the bowel decreases as the level of the anastomosis moves
more distally. Some patients with resection of the middle and low
rectum who require postoperative radiotherapy often have even worse
functional outcome due to chronic radiation injury to the bowel.
Creating a new rectum (neorectum)
from a section of descending colon folded and attached laterally to
itself in a "J" shape, and then attaching this to the upper
anal canal has been recently shown to improve functional outcome of
patients over conventional straight end to end anastomosis. Patients
have improved compliance of the neorectum, diminished frequency of
stools and diminished urgency and soiling. With the additional suture
lines in the pouch construction, usually a temporary diverting stoma (ileostomy)
is required. Activation of the pouch follows after confirmation of
satisfactory healing (generally 6-8 weeks). We have been offering this
form of reconstruction since 1997, and believe it is a significant
advance in the treatment of rectal cancer.
Total
Mesorectal Excision (TME) in the Operative Treatment of Rectal Cancer
The technique of
Total Mesorectal Excision (or Complete Circumferential Mesorectal
Excision) is not new. It was described in the early 1980s. Over the
last two decades an important shift in the operative technique of
rectal cancer resection has been toward TME as evidence mounts that
the oncologic results are superior. Conventional surgical techniques
of rectal resection, where blunt tissue dissection occurs along
unidentifiable tissue planes has given way to sharp dissection along
identifiable planes. TME removes the entire rectum along with its
entire surrounding mesentery(mesorectum), its surrounding fascia
(visceral fascia) and uninvolved circumferential margins.
Rectal resection with
TME has been reported to increase five-year rectal cancer survival
rates as well as decrease local rectal cancer recurrence rates.
Initially TME was thought to increase leak rates of anastomoses deep
in the pelvis, but recent studies suggest equivalent leak rates after
conventional rectal resection and rectal resection with TME. Since
fascial planes are followed and pelvic autonomic nerves spared,
compromise of sexual and bladder function is less with TME than
conventional techniques. Because of superior oncologic results, we
believe the technique of TME should be routinely employed when dealing
with middle or lower third rectal cancer.
Procedure
for Prolapse and Hemorrhoids-At a Glance
PPH is a technique developed in the early
'90's that reduces the prolapse of hemorrhoidal tissue by excising a
band of the prolapsed anal mucosa membrane with the use of a circular
stapling device. In PPH, the prolapsed tissue is pulled into a device
that allows the excess tissue to be removed while the remaining
hemorrhoidal tissue is stapled. This restores the hemorrhoidal tissue
back to its original anatomical position.
Advantages:
- Faster
procedure
- Less
postoperative pain
- Faster
return to "normal" activities
Dr. Young was the first Surgeon in our
area to begin performing the PPH
Procedure.
New
Artificial Sphincter for Incontinent Patients
The Acticon* Neosphincter is used in men
and women to treat severe fecal
incontinence. It is a small, fluid-filled prosthesis that is completely
implanted within the body. It is designed to mimic the natural function
of
the anal sphincter muscle, giving the patient control over bowel
movements.
Some 13 centers in the U.S. and a number of international sites were
selected to study the device in the fall of 1999. Soon after, Dr. Baker
was
selected for a training program on the AMS Acticon Neosphincter. Dr.
Baker
performed the first Acticon Neosphincter Implant in Tennessee in 2000.
For
more information, visit www.visitAMS.com.
