1. Resection principles: The mesenteric clearance technique
dictates the extent of resection and is determined by the nature
of the primary pathology, the intent of resection, the location
of the lesion, and the condition of the mesentery.
2. Minimally invasive resection: Laparoscopic and/or hand-assisted
laparoscopy has been shown to be both safe and efficacious for colorectal
3. Function after resection: Bowel function is often compromised
after colorectal resection, especially after low anterior resection.
For this reason, it is important to obtain a history of prior anorectal
trauma and/or incontinence before considering a low anastomosis.
4. Ostomies: Preoperative marking for a planned stoma is critical
for a patient’s quality of life. Ideally, a stoma should
be located within the rectus muscle, in a location where the patient
can easily see and manipulate the appliance, and away from previous scars,
bony prominences, or abdominal creases.
5. Inflammatory bowel disease: Both Crohn’s disease and
ulcerative colitis are associated with an increased risk of colorectal
carcinoma. Risk depends upon the amount of colon involved and the
duration of disease.
6. Pathogenesis of colorectal cancer: A variety of mutations have
been identified in colorectal cancer. Mutations may cause activation
of oncogenes (K-ras) and/or inactivation of tumor-suppressor
genes [adenomatous polyposis coli (APC) < DCC (deleted in
colorectal carcinoma), p53].
7. Early rectal cancer: Optimal treatment of very early rectal cancer
(T1NXMX) is controversial. Transanal excision alone has been associated
with a very high rate of local recurrence. In patients who will
tolerate and accept radical surgery, this approach is probably appropriate.
Chemoradiation either before or after transanal excision can also
be considered, but has not been prospectively studied.
8. Anal epidermoid carcinoma: Unlike rectal adenocarcinoma, anal
epidermoid carcinoma is treated primarily with chemoradiation. Surgery
is reserved for patients with persistent or recurrent disease.
9. Rectal prolapse: Rectal prolapse occurs most commonly in elderly
women. Transabdominal repair (rectopexy with or without resection)
offers more durability than perineal proctosigmoidectomy, but carries
greater operative risk.
10. Hemorrhoids: Hemorrhoids are cushions of submucosal tissue containing
venules, arterioles, and smooth muscle fiber. They are thought o
play a role in maintaining continence. Resection is only indicated
for refractory symptoms.
11. Fistula in ano: Treatment of fistula in ano depends upon the
location of the fistula, amount of anal sphincter involved in the
fistula, and the underlying disease process.
The embryonic GI tract begins developing during the fourth week of
gestation. The primitive gut is derived from the endoderm and divided
into three segments: foregut, midgut,
and hindgut. Both midgut and hindgut contribute
to the colon, rectum, and anus.
The midgut develops into the small intestine, ascending colon,
and proximal transverse colon, and receives blood supply from the superior
mesenteric artery. During the sixth week of gestation, the midgut
herniates out ...