Schwartz's General Surgery Colon, Rectum & Anus Flashcards

Colon
Terms Definitions
when does the embryologic development of the GI tract occur?
third week of gestation
which portions of the primitive gut contribute to the colon, rectum, and anus?
midgut and hindgut
what does the midgut develop into and what is the corresponding blood supply?
small intestine

ascending colon

proximal transverse colon

*SMA*
what happens to the midgut during the 6th-10th week of gestation?
it herniates and rotates 270 degrees COUNTERCLOCKWISE around the SMA, then returns back into the abdominal cavity
what does the hindgut develop into and what is the corresponding blood supply?
distal transverse colon

descending colon

rectum

proximal anus

*IMA*
what is the distal anal canal derived from and what is the blood supply?
ectoderm

internal pudendal artery
what anatomical marker divides the endodermal hindgut from the ectodermal distal anal canal?
the dentate line
what are the 5 layers of the colon and rectum from the inside out?
1. mucosa

2. submucosa

3. inner circular muscle

4. outer longitudinal muscle

5. serosa
in the colon, what is the outer longitudinal muscle separated into?
the teniae coli
describe the proximal and distal convergences of the teniae coli
proximal - converge at the appendix

distal - converge at the rectum at the level of the sacral promontory (retrosigmoid junction)
which muscle forms the internal anal sphincter?
the inner smooth muscle layer coalesces to form the internal anal sphincter
which portions are covered by serosa and which are not?
the intraperitoneal colon and proximal 1/3 of the rectum are covered by serosa: the mid and lower rectum does not have serosa
how long (in feet) is the average colon?
3-5 feet
what is the widest portion of the colon and how wide is it on average?
cecum

(7.5 to 8.5 cm)
what is the narrowest portion of the colon?
sigmoid colon

*most vulnerable to obstruction*
what portion of the colon has the thinnest muscular wall and why is this clinically relevant?
cecum

*most vulnerable to perforation*
which portions of the colon are fixed to the retroperitoneum?
ascending and descending colon
what tethers down the intraperitoneal transverse colon?
the gastrocolic ligament

colonic mesentery

greater omentum
is the sigmoid colon tethered to anything?
NO

this explains why volvulus is MC in the sigmoid colon, and why diverticulitis sometimes causes RLQ pain
describe the branches of the SMA and what portions of the colon they supply
SMA branches into the:

1. ILEOCOLIC artery (terminal ileum, proximal ascending colon)

2. RIGHT COLIC artery (ascending colon)

3. MIDDLE COLIC (transverse colon)
describe the branches of the IMA and the areas they supply
IMA splits into:

1. left colic artery (descending colon)

2. sigmoidal branches (sigmoid colon)

3. superior rectal artery (proximal rectum)
the terminal branches of each artery anastomose with the terminal branches of adjacent arteries forming what?
the marginal artery of Drummond
the veins of the colon all parallel their corresponding arteries except for which vein? describe it's course.
inferior mesenteric vein.

It ascends in the RETROPERITONEAL plane over the psoas muscle and continues posterior to the pancreas to join the splenic vein.
describe the blood supply to the distal rectum.
middle and inferior rectal arteries

(branches of the internal iliac)
describe the location of the following lymph nodes:
EPICOLOC
along the bowel wall
describe the location of the following lymph nodes:
PARACOLIC
along the inner margin of the bowel adjacent to the arterial arcades
describe the location of the following lymph nodes:
INTERMEDIATE
around the named mesenteric vessels
describe the location of the following lymph nodes:
MAIN
at the origin of the SMA and IMA
what is the sympathetic nerve innervation of the colon?
from T6-T12 and L1-L3
what is the parasympathetic innervation of the colon?
right and transverse colon: vagus nerve

left colon: sacral nerves S2-S4 (nervi erigentes)
how long is the average rectum?
12-15cm
what are the valves of Houston?
three distinct submucosal folds that extend into the rectal lumen
what marker defines the transition point between the columnar rectal mucosa and squamous endoderm?
the dentate (or pectinate) line
what are the columns of Morgagni?
longitudinal folds that surround the dentate line.
what empties into the columns of Morgagni and why is this clinically relevant?
anal crypts

*cryptoglandular abscesses can form here*
thee deep external anal sphincter is an extension of which muscle?
Puborectalis muscle
regarding rectal blood supply: the superior rectal artery is a branch of?
the IMA
regarding rectal blood supply: the middle rectal artery is a branch of?
the internal iliac
regarding rectal blood supply: the inferior rectal artery is a branch of?
internal pudendal artery, which is a branch of the internal iliac
what is sympathetic nerve supply to the anorectum?
S1-S3 fibers form the PREAORTIC plexus, which goes on to form the HYPOGASTRIC plexus, which goes on to form the PELVIC plexus
what is the parasympathetic nerve supply to the anorectum?
nervi energentes (from S2-S4)

*join sympathetic fibers to form the pelvic plexus*
the colon absorbs approximately ____% of water it receives from the ileal fluid?
90%
what is the major facilitator of this water absorption?
the Na-K-ATPase pump (water accompanies the transported sodium and is absorbed passively)
What happens to the K that is secreted into the colonic lumen by the N-K-ATPase pump?
it diffuses passively back across the colonic mucosa
what are an important source of energy for the colonic mucosa, and why is this clinically relevant?
short-chain fatty acids

*important because lack of them (dietary or surgical) may result in mucosal atrophy and diversion colitis*
what is the function of low amplitude, short duration contractions that occur in bursts in the colon?
move colonic contents both retrograde and antegrade to delay colonic transit and increase absorption time
How long is a flexible sigmoidoscope vs. a colonoscope?
60cm vs. 100-160cm
when is angiography the best study to detect a GI bleed?
when the bleeding is brisk (.5-1 mL per minute).
therapeutic advantages of angiography in a GI bleed?
can embolize or infuse vasopressin to stop bleeding
the resting pressure in the anal canal reflects the function of?
the internal anal sphincter (normal pressure 40-80 mm Hg)
the squeeze pressure in the anal canal reflects the function of?
external anal sphincter (normal pressure 40-80 mm Hg ABOVE resting pressure)
absence of the rectoanal inhibitory reflex is characteristic of what disease?
Hirschprung's disease
what can give a false positive on FOBT? (2)
red meat, vitamin C
Why is CEA not a valid screening test for colon CA?
only 60-90% of patients with colon CA have an elevated CEA. It is better to use CEA as a clinical marker for surveillance of recurrence once a baseline is established.
what is the MC source of GI hemorrhage and why is this clinically important?
esophageal, gastric or duodenal.

NG aspiration should always be performed in every GI bleed patient.
what conclusion can be made if bile is all that is obtained during NG aspiration in a GI bleed patient?
the bleeding is distal to the Ligament of Treitz (lower GI)
what are the 3 medical mainstays of treatment in constipation?
increased fiber, increased fluid intake, laxatives
causes of fecal incontinence can be classified into what 2 groups?
1) anatomic

2) neurogenic
describe some neurogenic causes of fecal incontinence
diseases of the CNS, pudendal nerve injury
describe some anatomic causes of fecal incontinence
congenital abnormalities, rectal prolapse, overflow incontinence secondary to infection or neoplasm, trauma
T/F: addition of dietary fiber improves fecal incontinence
True
an ileocolic resection involves removal of?
terminal ileum, cecum, appendix
which vessels are ligated in an ileocolic resection?
ileocolic vessels
what is the appropriate procedure for resection of a proximal colon CA?
right colectomy
which vessels are ligated in a right colectomy?
ileocolic vessels, right colic vessels, right branches of middle colic vessels
T/F: a portion of the terminal ileum is included in a right colectomy
TRUE

approximately 10cm of terminal ileum is included
what is the appropriate procedure for a patient with a hepatic flexure or proximal transverse colon CA?
extended right hemicolectomy
what does an extended right hemicolectomy include that a regular right hemicolectomy does not?
ligation of all of the middle colic vessels, a little bit more of the transverse colon.
which vessels are ligated in a transverse colectomy?
middle colic vessels
what is the appropriate procedure for excision of a disease specific to the distal transverse colon, splenic flexure, or descending colon?
Left Colectomy
which vessels are ligated in a left colectomy?
left branches of the middle colic vessels, left colic vessels, first branches of the sigmoid vessels
what is the procedure of choice for removing lesions located in the distal transverse colon?
extended Left colectomy
what is the difference between a Left Colectomy and an Extended Left Colectomy?
Extended L colectomy includes ligation of the right branches of the middle colic artery, as well as removal of more of the distal transverse colon.
what is the procedure of choice for a lesion in the sigmoid colon?
sigmoid colectomy
what vessels are ligated in a sigmoid colectomy?
sigmoid branches of the IMA
which vessels are ligated in a subtotal or total colectomy?
ileocolic,
right colic,
middle colic,
left colic
which vessels are NOT ligated in a subtotal or total colectomy?
superior rectal vessels
how long after a proximal ileostomy and J-pouch formation, can the ileostomy be taken down?
6-12 wks later

(after a contrast study confirms the integrity of the pouch)
what is the difference between a high anterior resection and a low anterior resection?
A high anterior resection removes less of the rectum (just the upper portion), where a low anterior resection removes the upper and mid rectum.
what is an extended low anterior resection?
resection down to the lower rectum, several cm above the rectal sphincter.
what is the best type of anastamotic configuration when the two ends of bowel are approximately the same size?
end-to-end
when is an end-to-side anastomotic configuration between two loops of bowel used?
when one limb of bowel is larger than the other
when is a side to end anastomotic configuration between two loops of bowel used?
when the proximal bowel is smaller than the distal bowel
an optimal stoma should be placed in which muscle?
within the rectus muscle
how wide should the fascial defect in the abdominal wall be to allow for a functioning stoma?
two to three fingers wide
in what settings would you place a temporary colostomy?
an anastamosis at risk for leakage or breakdown
which type of ileostomy is MC used as a temporary solution?
loop ileostomy
what is the preferred configuration of an permanent ileostomy?
end ileostomy
What is the MCC of stoma necrosis?
IMPAIRED VASCULAR SUPPLY

skeletonizing the distal small bowel,
overly tight fascial defect
T/F: obesity is a predisposing factor for stoma retraction
TRUE
what is the upper cutoff for ostomy output?
less than 1500mL

(otherwise dehydration with elecrolyte abnormalities may occur)
are most colostomies end colostomies or loop colostomies?
end colostomies
how is colostomy necrosis managed?
if it is above the fascia it may be managed expectantly,

if the necrosis extends below the fascia surgery is required
what % of patients develop pouchitis after an ileal pouch anal reconstruction?
50%
what are the two major bowel prep solutions?
polyethylene glycol

sodium phosphate
which bowel prep solution is more likely to cause electrolyte abnormalities?
sodium phosphate
which bowel prep solution works better?
they are equally effective
which bowel prep solution is more likely to cause bloating and nausea?
polyethylene glycol
incidence of ulcerative colitis in the US and Northern Europe?
8-15 per 100,000 people
what age group is UC MC diagnosed in?
third and seventh decades

(bimodal distribution)
incidence of Crohn's disease in the US and Northern Europe?
1-5 per 100,000 people
what age group is Crohn's disease MC diagnosed in?
15-30 years and 55-60 years


(also bimodal distribution)
what % of patients have inflammatory bowel disease that cannot be specified into UC or Crohn's, and what is this called?
15%

called indeterminate Colitis
what is backwash ileitis?
in UC. UC does not involve the small intestine, but the terminal ileum may demonstrate inflammatory changes due to "backwash."
which disease (UC or Crohn's) is the following characteristic of?

continuous involvement of the rectum and colon
UC
which disease (UC or Crohn's) is the following characteristic of?

rectal sparing?
Crohn's
which disease (UC or Crohn's) is the following characteristic of?

skip lesions?
Crohn's
which disease (UC or Crohn's) is the following characteristic of?

mucosal process only?
UC
severe abdominal pain and fever in a patient with IBD raises the concern of what complications?
toxic megacolon

fulminant colitis
which disease (UC or Crohn's) is the following characteristic of?

mucosal ulcerations?
Crohn's
which disease (UC or Crohn's) is the following characteristic of?

noncaseating granulomas?
Crohn's
chronic inflammation secondary to Crohn's disease ultimately results in what manifestations of the disease? (3)
fibrosis

strictures

fistulas
what liver changes may be seen in IBD?
fatty liver (40-50%)

cirrhosis (2-5%)
biliary manifestation of IBD?
primary sclerosing cholangitis

(40-60% of pts with primary sclerosing cholangitis have UC)
T/F: colectomy will reverse the primary sclerosing cholangitis
FALSE

the only effective therapy is liver transplantation
T/F: bile duct carcinoma is a complication of long-standing inflammatory bowel disease
TRUE
T/F: arthritis usually improves upon treatment of IBD
TRUE
what are the skin lesions classically associated with IBD and what do they look like? (2)
1) erythema nodosum

(raised, red and predominantly on the lower legs)

2) pyoderma gangrenosum

(can ulcerate and become a painful, necrotic wound)
what are the five main categories of medical treatment for IBD?
1) salycilates
2) antibiotics
3) corticosteroids
4) immunosuppressive agents
5) nutrition
MOA of azathioprine and 6-mercaptopurine?
antimetabolite drugs that interfere with nucleic acid synthesis and thus decrease proliferation of immune cells (IMMUNOSUPPRESSANT)
what is the time of onset of azathioprine and 6-mercaptopurine?
6-12 wks

(concommittent use of corticosteroids almost always required)
T/F: a complete evaluation with a colonscopy and/or barium enema is indicated in a patient with an acute flare of UC
FALSE

risk of perforation
what should be done when a stricture is found in a patient with UC?
the stricture should be presumed to be malignant until proven otherwise
indications for urgent surgery in a UC patient?
hemorrhage, toxic megacolon, fulminant colitis (when it fails medical therapy)
what is the medical therapy for fulminant colitis? (4)
bowel rest, hydration, broad spectrum antibiotics, IV corticosteroids
what is the risk of malignancy in a pancolonic UC patient 10, 20 and 30 years after diagnosis?
2% after 10 years
8% after 20 years
18% after 30 years
describe the type of colonoscopic surveillance in long-standing UC patients
multiple (40-50) random biopsies
when is surveillance recommended for pancolitis, left-sided colitis?
* pancolitis: annually after 8 years


* left-sided colitis: annually after 15 yrs
what procedure is advised in patients who have dysplasia on a screening biopsy? why?
proctocolectomy (if possible, restorative proctocolectomy with ileal pouch-anal anastamosis)

(up to 20% of patients with low-grade dysplasia have a concommittant invasive cancer)
what procedure is advised in patients with UC who undergo emergent operation (ie. for fulminant colitis, toxic megacolon)?
total abdominal colectomy with end ileostomy
what is the MC site of involvement in Crohn's?
terminal ileum/cecum
acute Crohn's disease is also known as the ______________ stage, whereas chronic Crohn's is also known as the ____________ stage.
acute inflammatory stage

chronic fibrotic stage
T/F: when resecting bowel in Crohn's, the margins must be microscopically negative.
FALSE

*it is advised to remove the least amount of bowel possible, and GROSSLY normal margins should be left*
what are the top 2 MCC of surgery in Crohn's disease?
internal fistula or abscess (30-38%),
obstruction (35-37%)
T/F: Crohn's disease never involves the rectum
FALSE

*rectum is spared in ~40% of Crohn's patients*
anal manifestations of Crohn's disease?
fissures, fistulas, perianal abscesses
what type of anal fissure raises suspicion of Crohn's disease?
unusually deep or broad,
located in a lateral position (rather than in the anterior or posterior midline)
T/F: in a Crohn's patient: anal skin tags and/hemorrhoids should be immediately excised
FALSE

these should NOT be excised unless they are extremely symptomatic because of the risk of chronic, nonhealing wounds
are the majority of colonic diverticulae true or false?
false diverticulae
what's the difference between a true and false diverticula?
FALSE diverticula - when the mucosa and muscularis mucosa herniate through the colonic wall

TRUE - a diverticula that contains all layers of the bowel wall (rare, congenital)
where (anatomically) in the bowel wall do false diverticula tend to occur?
between the teniae coli, at points where the main vessels penetrate the colon wall (creating a spot of weakness in the colon muscle)
how common are diverticulae?
common in older individuals. over 50% of Americans over age 50 have diverticula
where is the MC site of diverticulosis?
the sigmoid colon
what is the most accepted theory for the formation of diverticula?
lack of dietary fiber results in less stool volume, requiring higher intraluminal pressure and high colonic wall tension for propulsion. the increased pressure creates the diverticula.
T/F: a high fiber diet has been shown to decrease the incidence of diverticulosis.
TRUE
how often does diverticulitis occur in people with diverticulosis?
10-25% of the time
what is recommended after the second episode of uncomplicated diverticulitis and why?
elective sigmoid colectomy with primary anastamosis

(the risk of complications increases with each recurrence)
what must be done after resolution of an acute episode of diverticulitis?
evaluation for malignancy (either by sigmoidoscopy or colonoscopy)
what constitutes complicated diverticulitis?
diverticulitis with:

abscess, obstruction, diffuse peritonitis (free perforation), or fistulas
what is a Hinchey stage I diverticulitis?
colonic inflammation with an associated pericolic abscess
what is a Hinchey stage II diverticulitis?
colonic inflammation with a retroperitoneal or pelvic abscess
what is a Hinchey stage III diverticulitis?
purulent peritonitis
what is a Hinchey stage IV diverticulitis?
fecal peritonitis
treatment of an abscess associated with diverticulitis that is small (<2cm diameter)?
IV antibiotics
treatment of an abscess associated with diverticulitis that is larger than 2cm?
CT guided percutaneous drainage
treatment of a Hinchey stage I and II diverticulitis with associated abscesses?
sigmoid colectomy with primary anastamosis
treatment of a Hinchey stage III and IV diverticulitis with associated abscesses?
sigmoid colectomy with end colostomy and Hartmann pouch
what % of patients with complicated diverticulitis develop fistulas between the colon and adjacent organs?
5%
what is the MC type of fistula that develops in complicated diverticulitis?
colovesical
what tests can be used to evaluate fistulas?
costrast enema and/or small bowel follow-through
in a patient with a lower GI hemorrhage due to diverticulitis, how often will the bleeding stop spontaneously?
80% of the time
what is the dominant risk factor for colon CA?
age
____% of colorectal cancers areise spontaneously, whereas ___% arise in patients with a known family history.
80% spontaneous

20% familial
what type of diet is correlated with an increased incidence of colorectal CA?
high in animal fat, low in fiber
what type of diet is correlated with a decreased incidence of colorectal CA?
high in vegetable fiber
any correlation between lifestyle/BMI and mortality in colon CA?
obesity and sedentary lifestyle have an increased mortality in colon CA
T/F: there is a correlation between acromegaly and colon CA
TRUE
In the pathogenesis of colorectal CA: what are the two major TYPES of genetic mutations that predispose?
activation of oncogenes

inactivation of tumor-suppressor-genes
example of an oncogene activated in colorectal CA?
K-ras
tumor suppressor genes commonly inactivated in colorectal CA? (3)
APC, DCC, p53
which genetic defect is associated with FAP?
defects of the APC gene
T/F: in FAP, the site of mutation on the APC gene correlates with the clinical severity of the disease
TRUE
T/F: an APC gene mutation alone results in colorectal CA?
FALSE

(An APC mutation sets the stage for accumulation of genetic damage that results in malignancy via the loss of heterozygosity pathway)
explain the loss of heterozygosity (LOH) pathway that results in colorectal carcinoma
An APC mutation sets the stage for additional mutations via LOH. These mutations include K-ras activation, loss of DCC and/or p53.
what happens on a molecular level when K-ras is mutated?
A K-ras mutation results in the inability to hydrolize GTP, thus leaving the G-protein permanently activated. This leads to uncontrolled cell division.
DCC mutations are present in >____% of colon carcinomas
>80%
what happens on a molecular level when p53 is mutated?
an inactivated p53 protein results in NO APOPTOSIS of genetically damaged cells.
mutations in p53 are present in ____% of colon carcinomas
75%
what are the two major pathways for tumor initiation and progression in colorectal CA?
Loss of heterozygosity (LOH)

replication error (RER)
80% of colorectal carcinomas are thought to arise from which pathway?
LOH
describe the replication error (RER) pathway of tumor initiation and progression
RER is characterized by errors in MISMATCH REPAIR during DNA replication
T/F: in FAP, the site of mutation on the APC gene correlates with the clinical severity of the disease
TRUE
T/F: an APC gene mutation alone results in colorectal CA?
FALSE

(An APC mutation sets the stage for accumulation of genetic damage that results in malignancy via the loss of heterozygosity pathway)
explain the loss of heterozygosity (LOH) pathway that results in colorectal carcinoma
An APC mutation sets the stage for additional mutations via LOH. These mutations include K-ras activation, loss of DCC and/or p53.
what happens on a molecular level when K-ras is mutated?
A K-ras mutation results in the inability to hydrolize GTP, thus leaving the G-protein peramanently activated. This leads to uncontrolled cell division.
DCC mutations are present in >____% of colon carcinomas
>80%
what happens on a molecular level when p53 is mutated?
an inactivated p53 protein results in NO apoptosis of genetically damaged cells.
mutations in p53 are present in ____% of colon carcinomas
75%
what are the two major pathways for tumor initiation and progression in colorectal CA?
Loss of heterozygosity (LOH)

replication error (RER)
80% of colorectal carcinomas are thought to arise from which pathway?
LOH
describe the replication error (RER) pathway of tumor initiation and progression
RER is characterized by errors in mismatch repair during DNA replication
hMSH2, hMLH1, hPMS1, hPMS2 NS HMSH6/GTBP are all examples of?
mismatch repair genes that are mutated in the RER pathway. A mutation in these predisposes a cell to mutations, which may occur in proto-oncogenes or tumor suppressor genes.
Is a colon tumor with microsatellite instability (MSI) more likely to be right or left sided?
right sided
Does a colon tumor with microsatellite instability (MSI) have a better or worse prognosis than a tumor with microsatellite stability?
better prognosis
where do colorectal tumors that arise from the LOH pathway tend to occur?
distal colon
are colorectal tumors that arise from the LOH pathway associated with a better or worse prognosis?
worse prognosis
tubular adenomas are associated with a ___% chance of malignancy?
5%
villous adenomas are associated with a ___% chance of malignancy?
40%
tubulovillous adenomas are associated with a ___% chance of malignancy?
22%
Invasive carcinomas are rare in polyps smaller than what size?
<1 cm
what is the risk of carcinoma in a polyp larger than 2 cm?
35-50%
how is a microperforation during colonoscopy and polypectomy managed?
bowel rest,
broad spectrum antibiotics,
close observation
Another name for Juvenile Polyps is?
Hamartomatous Polyps
T/F: hamartomatous (juvenile) polyps are usually premalignant
FALSE
what is the concern with familial juvenile polyposis?
that the lesions may degenerate into adenomas, and then into carcinomas
when should annual screening begin for a patient with familial juvenile polyposis?
10-12 yrs old
which disorder is also associated with characteristic melanin spots on the buccal mucosa and lips?
Peutz-Jeghers syndrome
what are the screening recommendations for Peutz-Jeghers syndrome?
baseline colonoscopy and EGD at 20 yrs, annual flex sig thereafter
what is Cronkite-Canada syndrome?
gastrointestinal polyposis that is associated with alopecia, cutaneous pigmentation, atrophy of fingernails and toenails.
main symptoms of Cronkite-Canada syndrome?
diarrhea, vomiting, malabsorption
prognosis in Cronkite-Canada syndrome?
most patients die of their disease despite maximal medical therapy
Which syndrome is an autosomal dominant disorder that involves hamartomas of all three embryonal cell layers? It is manifested by facial trichilemomas, breast CA, thyroid disease and GI polyps.
Cowden's syndrome
T/F: small (<5cm) hyperplastic polyps are considered premalignant
FALSE

*have hyperplasia but no dysplasia - cannot be distinguished from adenomatous polyps and therefore are often removed. large hyperplastic polyps (>5cm) have a risk of malignant degeneration*
what is the genetic abnormality in Familial Adenomatous Polyposis (FAP)?
mutation in the APC gene
what % of patients with FAP have no other affected family members?
up to 25%
what is the lifetime risk of colorectal CA in patients with FAP?
100% by age 50
screening recommendations for a patient with an identified APC mutation and a family history of FAP?
flex sig starting at age 10-15 until polyps are identified
screening recommendation for a patient with a family history of FAP but tests negative for an APC mutation?
screening as per average risk guidelines (starting at age 50)
what other GI carcinoma is a particular concern in patients with FAP? Screening recommendations?
periampullary carcinoma (duodenal)

*screen with EGD every 2-3 yrs starting at age 25-30*
what is attenuated FAP?
a genetic variant of FAP in which it develops later in life with fewer polyps, mostly in the Right colon
T/F: colorectal cancer occurs in patients with attenuated FAP just as frequently as regular FAP
FALSE

~50% of patients with FAP develop colon CA, but later (50 yrs old)
what is the other name for Lynch's syndrome?
Hereditary Nonpolyposis Colon Cancer (HNPCC)
which is more common, HNPCC or FAP?
HNPCC
what is the genetic background to HNPCC?
mismatch repair (RER)
inheritance pattern of HNPCC?
autosomal dominant
at what age do patients with HNPCC develop colorectal carcinoma?
40-45 yrs
what % of individuals with the HNPCC mutation will develop colorectal CA?
70%
what is the prognosis when a patient with HNPCC is diagnosed with colon CA?
better than non HNPCC colon CA
in HNPCC individuals, where is the colon cancer most likely to appear?
right colon
what other extracolonic malignancies is HNPCC associated with?
endometrial, ovarian, pancreatic, stomach, small bowel, biliary, urinary tract
what is the Amsterdam criteria for clinical diagnosis of HNPCC?
THREE AFFECTED RELATIVES with histologically verified adenocarcinoma of the large bowel (one must be a first degree relative of one of the others) in TWO SUCCESSIVE GENERATIONS with one patient DIAGNOSED BEFORE AGE 50.
nonsydromic familial colorectal cancer occurs in what % of patients with colorectal CA?
10-15%
what is the risk of developing colon CA if one first-degree relative is affected?
12%
what is the risk of developing colon CA if two first-degree relatives are affected?
35%
what is the risk of developing colon CA in the general population?
6%
screening recommendations for nonsyndromic familial colorectal cancer?
colonoscopy beginning at age 40 OR 10 yrs before the age of the earliest diagnosed family member, whichever is first
screening recommendations for colorectal CA in the general population?
beginning at 50yrs: yearly FOBT, flex sig every 5 yrs OR colonoscopy every 10 yrs
what is the MC form of spread in colorectal CA?
lymphatogenous spread to regional lymph nodes
what is the single most predictor of lymph node spread in colorectal CA?
T stage (depth of invasion)
T/F: Tis stage colorectal CA has a risk of lymph node metastasis
FALSE.

Tis (carcinoma in situ, no penetration of the muscularis mucosa) has NO risk of metastasis.
small lesions confined to the bowel wall (T1 and T2) have what % chance of lymph node metastasis?
5-20%
larger tumors that invade bowel wall or adjacent organs (T3-T4) have what % chance of lymph node metastasis?
>50%
T/F: the number of lymph nodes with metastases correlates with the presence of distant disease
TRUE
___ or more involved lymph nodes predicts a poor prognosis
FOUR
what route does lymph drainage take from the upper rectum?
along the superior rectal vessels to the inferior mesenteric nodes
what route does lymph drainage take from the lower rectum?
along the middle rectal vessels
MCC of metastasis from colorectal cancer?
Liver
in colorectal cancer, (with regard to the tumor) the chance of liver metastasis increases with increased _____________ and ____________.
tumor size
tumor grade
via which method of spread does hepatic and lung metastasis occur in colorectal cancer?
hematogenous spread
via which method of spread does peritoneal metastasis occur in colorectal cancer?
carcinomatosis
Describe the Following T stage in relation to colorectal carcinoma: Tx
cannot be assessed
Describe the Following T stage in relation to colorectal carcinoma: T0
NO evidence of cancer
Describe the Following T stage in relation to colorectal carcinoma: Tis
carcinoma in situ
Describe the Following T stage in relation to colorectal carcinoma: T1
tumor invades submucosa
Describe the Following T stage in relation to colorectal carcinoma: T2
tumor invades muscularis propria
Describe the Following T stage in relation to colorectal carcinoma: T3
tumor invades through muscularis propria into submucosa or peritoneal tissues
Describe the Following T stage in relation to colorectal carcinoma: T4
tumor directly invades other organs or tissues or perforates the visceral peritoneum of specimen
Describe the Following Nodal stage in relation to colorectal carcinoma: Nx
Regional lymph nodes cannot be assessed
Describe the Following T stage in relation to colorectal carcinoma: N0
No lymph node metastasis
Describe the Following T stage in relation to colorectal carcinoma: N1
mets to 1-3 pericolic or perirectal nodes
Describe the Following Nodal stage in relation to colorectal carcinoma: N2
mets to 4 or more pericolic or perirectal lymph nodes
Describe the Following Nodal stage in relation to colorectal carcinoma: N3
mets to any lymph node along a major named vascular trunk
Describe the Following M stage in relation to colorectal carcinoma: Mx
presence of distant metastasis cannot be measured
Describe the Following M stage in relation to colorectal carcinoma: Mo
No distal metastasis
Describe the Following M stage in relation to colorectal carcinoma: M1
Distant metastasis present
describe a stage I colorectal cancer
tumor invades through the muscularis mucosa but is confined to the subucosa (T1) or the muscularis propria (T2).

*T1-2, N0, M0*
describe a stage II colorectal cancer
tumor invades through the bowel wall into the subserosa or pericolic/perirectal tissues,
or into other organs or tissues (T3) or through the visceral peritoneum (T4) without nodal mets.

*T3-T4, N0, M0*
describe stage III colorectal cancer
any T stage with nodal metastasis.

*Tany, N1-3, M0*
describe stage IV colorectal cancer
any T, any N, distal metastasis

*Tany, Nany, M1)
5 year survival of stage I colorectal cancer?
70-95%
5 year survival of stage II colorectal cancer?
55-65%
5 year survival of stage III colorectal cancer?
40-60%
5 year survival of stage IV colorectal cancer?
0-16%
in a patient with a diagnosed colorectal tumor, why is a preoperative colonoscopy indicated?
synchronous tumors are present in up to 5% of patients
treatment for stage 0 colon cancer?
polyp excision - no risk of lymph node metastasis. follow with frequent colonoscopy.
A malignant polyp would be what stage of colon cancer?
Stage I
what is the risk of metastasis in a pedunculated polyp with invasive carcinoma in the head, no stalk involvement?
<1%
what is done if a polyp is excised endoscopically and the margins are <1mm or lymphovascular invasion is seen?
segmental colectomy
up to ___% of patients with completely resected stage II disease will ultimately die from colon cancer
50%
what are the Schwartz "descriptive titles" for the following colon cancer stages:
Stage I:
Stages I and II:
Stage III:
Stage IV:
Stage I: the malignant polyp.
Stages I and II: localized colon carcinoma.
Stage III: Lymph node metastasis.
Stage IV: Distnant metastasis
treatment for stage III colon cancer?
adjuvant chemotherapy

*5-FU and levamisole or leukovorin*
patients with a solitary colon cancer metastasis to the liver who undergo resection have what 5-year survival?
20-40%
which has a higher chance of recurrence once excised: colon CA or rectal CA?
rectal CA
what does TEM stand for in relation to rectal CA?
Transanal Endoscopic Microsurgery
what does a pelvic exenteration entail?
an APR WITH en bloc resection of the ureters, bladder, prostate, bladder and prostate or uterus&vagina
treatment of stage 0 rectal CA?
local excision with 1cm margins
treatment of stage I localized rectal carcinoma?
radical resection

(20-40% recurrence rate with local excision only)
postop surveillance of colorectal CA pts?
colonoscopy within 12 months. if normal, repeat colonoscopy 3-5 yrs later.
when do most recurrences of colorectal cancer occur?
within 2 yrs
how often and for how long is the CEA level followed in postop colorectal CA pts?
every 2-3 months for 2 yrs.
what is the goal in a sentinel lymph node biopsy for colorectal carcinoma?
to improve staging

*not to avoid radical lymphadenectomy as in breast and melanoma excisions*
is rectal prolapse MC in men or women?
women
(6:1)
in what decade does rectal prolapse peak?
7th decade
Three major procedure names for repair of rectal prolapse?
1. Moschowitz repair

2. Ripstein and Wells rectopexy

3. resection of redundant sigmoid colon
what is the Moschowitz repair of rectal prolapse?
reduction of the perineal hernia and closure of the cul-de-sac
what is the Ripstein and Wells Rectopexy?
fixation of the rectum (either with a prosthetic sling or by suture rectopexy)
what rectal prolapse repair offers the most durable repair?
abdominal rectopexy (<10% recurrence)
solitary rectal ulcer syndrome and colitis cystica profunda are commonly associated with what other condition?
internal intussusception.
what part of the colon is MC associated with volvulus?
sigmoid
plain abdominal films of a sigmoid volvulus reveal what classic sign?
coffee bean appearance

(convexity loop lies opposite the side of obstruction, in the RUQ)
in a sigmoid volvulus a gastrograffin enema shows what characteristic sign?
bird's beak
what is the initial management strategy of a sigmoid volvulus?
resuscitation followed by endoscopic detorsion
what is the risk of recurrence of a volvulus after endoscopic detorsion?
40%
(high. for this reason, a sigmoid colectomy should be performed after the patient has been stabilized and undergone adequate bowel prep)
what should be done in a sigmoid colectomy when dead bowel is present?
end colostomy (Hatmann procedure)
a cecal volvulus results from?
nonfixation of the right colon. rotation occurs around the ileocolic blood vessels and vascular impairment occurs early
can a cecal volvulus be detorsed endoscopically?
NO
(almost never)
treatment for a cecal volvulus?
surgical exploration, right hemicolectomy with primary ileocolic anastamosis
which disease results from failure of migration of neural crest cells to the distal large intestine?
Hirschsprung's disease (congenital megacolon)
what can cause acquired megacolon?
infection (Trympanazoma cruzi - Chaga)
-or-
chronic constipation
mechanism by which Chagas disease causes acquired megacolon?
destroys ganglion cells and thereby produces both megacolon and megaesophagus
what is Ogilvie's syndrome?
colonic pseudo-obstruction

*a functional disorder in which the colon becomes massively dilated in the absence of mechanical obstructon*
what 3 things is Ogilvies syndrome MC associated with?
*MC seen in hospitalized patients*
1. bedrest

2. narcotics

3. comorbid desease
what drug can be given to decompress a colon in Ogilvie's syndrome and what are its side effects?
neostigmine

*transient but profound bradycardia*
which portions of the colon are dilated in Ogilvie's syndrome?
right and transverse
what is the MC site of intestinal ischemia?
splenic flexure
why is the rectum relatively spared from intestinal ischemia?
rich collateral flow
what causes the "thumb-printing" seen on plain films of ischemic colitis?
mucosal edema
submucosal hemorrhage
why is sigmoidoscopy relatively contraidicated in any patient with significant abdominal tenderness?
sigmoidoscopy may precipitate perforation
what is the mainstay of therapy in ischemic colitis?
bowel rest and broad spectrum antibiotics

*80% successful*
what is the leading cause of nosocomially acquired diarrhea?
Clostridium difficile colitis
(pseudomembranous colitis)
T/F: even a single dose of antibiotic can cause C.diff colitis
TRUE
describe the toxins produced by C. difficile that cause the colitis
Toxin A - an enterotoxin
Toxin B - a cytotoxin
Treatment for C. diff?
STOP ANTIBIOTIC

metronidazole (first line) or vanco
describe the locations of the 3 hemorrhoidal cushions
left lateral
right anterior
right posterior
what is the difference between external and internal hemorrhoids?
EXTERNAL - distal to the dentate line, covered with richly innervated anoderm

INTERNAL - proximal to dentate line, covered by insensate anorectal mucosa
main problem with external hemorrhoids?
pain
main problem with internal hemorrhoids?
bleeding
what is a first degree hemorrhoid?
bulge into the anal canal, may prolapse beyond the dentate line upon straining.
what is a second degree hemorrhoid?
one that prolapses through the anus but reduces spontaneously.
What is a third degree hemorrhoid?
one that prolapses through the anal canal and requires manual reduction.
What is a fourth degree hemorrhoid?
one that is prolapsed and cannot be reduced - at risk for strangulation.
medical therapy for hemorrhoids?
dietary fiber,
stool softeners,
increased fluid intake,
avoidance of straining
therapeutic options for hemorrhoid therapy?
rubber band ligation
IR photocoagulation
Sclerotherapy
Excision, hemorrhoidectomy
IR photocoagulation works best on what degree hemorrhoids?
1st and 2nd degree
Long term sequelae of a hemorrhoidectomy? (3)
incontinence,
anal stenosis,
ectropion (Whitehead's deformity)
what is the pathophysiology of an anal fissure?
a tear in the anoderm distal to the dentate line causes spasm of the internal anal sphincter. This results in pain, increased tearing, and decreased blood supply. Result is a cycle of pain, spasm, ischemia and a poorly healing wound.
where do the vast majority of anal fissures occur?
in the posterior midline
where do <1% of anal fissures occur, and if they do, bring up a suspicion of Crohn's?
off midline
what is seen on examination of a chronic anal fissure that is not seen in an acute anal fissure?
external skin tag/hypertrophied anal papilla
non surgical therapy for anal fissures?
bulk agents, stool softeners, warm sitz baths
What is the procedure of choice in treating an anal fissure?
Lateral Internal Sphincterotomy (LIS)
How much of the internal sphincter is divided in an LIS?
~30%
anorectal abscesses MC result from infections of what glands?
the anal glands (cryptoglandular infection)
The space that surrounds the anus and laterally becomes contiguous with the fat of the buttocks is called?
the PERIANAL space
What is the name of the space that separates the internal and external anal sphincters?
the INTERSPHINCTERIC space
What is the name of the space that is located lateral and posterior to the anus?
the ISCHIORECTAL space

(ischiorectal fossa)
The two ischiorectal spaces converge posteriorly to form what space?
the DEEP POSTANAL space
where do the supralevator spaces lie?
above the levator ani on either side of the rectum, communicate posteriorly
in which space do the inferior rectal vessels and lymphatics lie?
the ischiorectal space
what is the MC type of abscess in the rectal area?
perianal abscess
how does a perianal abscess present on physical exam?
painful swelling at the anal verge
primary treatment of anorectal abscesses?
Incision and Drainage
are antibiotics routinely administered after I&D of a perianal abscess?
NO

*only give if extensive overlying cellulitis, immunocompromised, DM, valvular heart disease*
Postoperative care of a perianal abscess?
no packing

sitz baths
which type of perianal abscess manifests as a "horseshoe abscess"?
inschiorectal
what is the mortality rate of a necrotizing perineal soft tissue infection?
50%
drainage of an anorectal abscess results in a cure what % of the time?
50%
what about the other 50% with an anorectal abscess who are not cured?
they go on to develop a fistula in ano
A complex, recurrent, or nonhealing fistula in ano should raise the suspicion of what diagnoses? (3)
* Crohn's
* malignancy
* radiation
* unusual infection (TB, actinomycosis, chlamydia)
what is Goodsall's rule?
a guide to determining the internal opening of a fistula.
*anterior external opening: usually connects to an interior opening by a STRAIGHT tract.
*posterior external opening: usually connects to the midline in a CURVED track.
what is the exception to Goodsall's rule?
an anterior external opening that is >3cm from the anal margin: these track to the posterior midline.
what is the mortality rate of neutropenic enterocolitis (typhlitis)?
>50%
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