Colon & Rectum 2 Flashcards
Peak ages of Crohn’s dx?
15-30 yrs
second peak 55-80 yrs
This is a risk factor for Crohn’s dx;
smoking
after resection, risk of recurrence is greater in smokers
What genetic factor assc. w/Crohn’s dx?
NOD2/CARD15 gene, on chrom 16–> activates NF-kB
What are some gross pathological descriptions that characterize Crohn’s dx?
transmural inflammation with thickened colon
mucosa has a cobblestone appearance
bowel wall encased by creeping fat of the mesentery
normal mucosa may intervene with areas of inflammation
(skip lesions)
What do we see histologically in pts with Crohns?
transmural inflammation, submucosal edema, lymphoid aggregates and ultimately fibrosis
What is the pathognomonic histological feature of Crohn’s dx?
non-caseating granuloma
This is a localized, well formed, aggregate of lymphocytes and giant cells seen in Crohn’s dx:
non-caseating granuloma
Is the rectum involved in Crohn’s dx pts?
NO NO NO
What is the characteristic triad of sx seen in pts with Crohn’s dx?
abdominal pain
diarrhea
weight loss
Linear ulcers on the mucosa of involved intestine in Crohn’s dx is termed what?
railroad track or bear claw ulcers
What are some aspect of Crohn’s that affect the anus?
fistulae
fissures
strictures
erosion of anoderm
How do we diagnose Crohn’s colitis?
combination of endoscopy, clinical, radiologic features
Medical therapy for Crohns dx?
aminosalycilates
steroids
immunomodulators
What monoclonal antibody has been shown to be effective in tx of Crohns by targeting TNF-a receptor and helping pts with chronic fistulas?
infliximab
When do we operate on pt’s for Crohn’s dx?
medical intractability cancer massive bleeding fistulas intestinal obstruction abscess fulminant colitis/megacolon growth retardation
Most common indication for surgical management of Crohns?
medical non-responsiveness
Risk of cancer with Crohn’s dx?
not as high as UC, but present
presence of high grade dysplasia of colon is indication for colectomy
Extracolonic manifestation of Crohn’s dx are similar to UC, do they improve with surgery?
most improve after diseased bowel is resected
What’s the mainstay of tx for Crohns dx?
medical therapy
surgery is not curative
What is an important principle in surgical management of Crohn’s dx?
resect only enough intestine to improve symptoms
free disease margin are usually seen on gross inspection
resecting grossly normal appearing intestine can lead to short bowel syndrome
When do we perform an ileo-cecal resection for Crohn’s pts?
in pts with severe disease of terminal ileum with obstruction or perforation
6-12 inches of terminal ileum resected, then we anastomose ileum to ascending colon
recurrence rate at 10 yrs after ileo-colic resection is 50%
Usually terminal ileitis often confused with appendicitis, and at time of surgery for appendicitis with normal appearing appendix, what is done?
if cecum is normal and appendix normal, remove appendix
leave ileum intact
When do we perform a total proctocolectomy with end ileostomy for pts with Crohns? (removal of all abdominal colon, rectum, anus)
indicated for pts with dx of entire colon, rectum
or when fecal incontinence too severe to preserve rectum
disadvantage; delayed healing of perineal wound, malabsorption problems
When do we perform a total abdominal colectomy with ileo-rectal anastomosis for Crohns dx?
pts who have rectal sparing and anus sparing
pts have 4-6 bowel movements daily
has high likelihood of recurrence, requiring completion proctectomy and ileostomy
When do we perform segmental colon resections in pts with Crohn’s dx?
pts with disease limited to a segment of colon
seen in 10-20 % of pts
What is a major disadvantage of segmental colon resection in pts with Crohns dx?
high rate of recurrence requiring subsequent operations
60% of pts need re-operation at 10 yrs
What are some risk factors for recurrence of Crohn’s dx?
duration + severity of dx
smoking
presence of granulomas in resected specimen
What is the re-operative rate of Crohn’s dx pts?
4-5%/year
Leading cause of infectious colitis worldwide?
c. jejuni
(causes bloody diarrhea, abd pain, f/n/v)
dx–> dark-field microscopy
tx–> cipro
This cause of infectious colitis can mimic appendicitis and Crohn’s dx;
yersinia enterocolitica (bloody diarrhea, abd pain)
dx–> stool
tx–> supportive, rare cases TMP-SMX
THis is a gram +, spore forming anaerobic organism which has two forms;
c. diff
active infectious form that can’t survive in environment
inactive spore form that can survive in environment
What toxins does c. diff release that are causes of pseudomembranous colitis?
toxin A/B
What toxin of c.diff is directly responsible for infectious colitis?
toxin A
binds to colonocyte glycoprotein receptor–> destruction of colonocytes, inflammatory response
What does toxin B of c. diff do?
potent cytotoxin with potential to cause colitis
When do we usually see c. diff colitis?
4-9 days after abx use
25% of pts don’t become symptomatic until 10 weeks later
What is pseudomembranous colitis seen with Crohn’s dx?
inflamed mucosa covered by yellowish-plaque like membranes
made up of inflammatory cells, fibrin, bacterial components
seen in 25% of mild dx
seen in 87% of fulminant colitic dx
Tx for c. diff?
vanco vs metronidazole equally effective
see a respone in 3-4 days
tx continued for 10 days
relapse seen in 25% of pts
What do we do for pts with refractory c. diff colitis?
fecal transplant
Severe cases of c. diff progress to fulminant colitis or toxic megaocolon, in such cases what surgical procedure is needed?
abdominal colectomy with ileostomy
Mortality rate of c. diff toxic megacolon requiring colectomy with ileostomy is?
50%
Most common form of intestinal ischemia?
colonic ischemia
usually transient and resolve spontaneously
Some causes of colonic ischemia?
aortic surgery
atherosclerotic dx
conditions that cause transient hypotension
In colonic ischemia what is the most vulnerable layer of the intestinal lumen?
mucosa (usually recovers well)
if ischemia goes to muscularis layer–> strictures, scarring
full thickness ischemia–> gangrene, peritonitis
What segment of large bowel is most susceptible to ischemia?
sigmoid
Surgical treatment for colonic ischemia is rare, but when done what is done?
partial or total colectomy with or without a stoma
Adenocarcinoma of colon ranks where with men & women?
3rd
men; lung, prostate, colon
women: lung, breast, colon
What’s the lifetime risk of developing colon cancer in US
- 5% men
5. 1 % women
Rate of developing invasive colorectal cancer increases with age;
more than 90% of new cases diagnosed after 50 yrs age
In what ways is colorectal cancer inherited?
sporadic
hereditary
familial
What are some hereditary conditions that predispose to colorectal cancer?
FAP
Hereditatory non-polyposis colo-rectal cancer
This form of colon cancer occurs in abscence of family hx, usually seen in pts 60-80 yrs old, usually presents as an isolated lesion;
sporadic
Patients with first degree relatives with colo-rectal cancer and index case in family < 50, have what?
increased risk of developing colon cancer
The earliest mutation in the adenoma-carcinoma sequence of colon cancer occurs with mutation of what gene?
APC gene (tumor suppressor gene)
How is familial adenomatous polyposis inherited?
AD
Gene messed up in FAP?
APC gene
This inherited entity is characterized by > 100 adenomatous polyps in the colon and rectum:
FAP
most of the polyps go thru the adenoma-carcinoma sequence, so most pts die by age 50 if not surgically treated
This syndrome had diffuse colonic adenomatous polyps + osteomas of mandible/skull, desmoid tumors, periampullary neoplasms;
Gardner’s syndrome
Most frequently mutated tumor suppressor gene in human neoplasia is?
p53
mutations seen in 75% of colon cancer pts, occur late in adenoma-carcinoma sequence
Mutations in mismatch repair genes cause what entity?
HNPCC
(MLH1, MSH2, 3
lead to microsatetille instability
Colorectal carcinomas arise from benign polyps through this well established sequence;
adenoma to invasive carcinoma sequence
How do we describe types of polyps we see intra-luminally?
pedunculated–> with a stalk
sessile–> flat, not stalk
What are the three types of colonic polyps we see commonly?
tubular adenomas (65-80%) villous adenomas (10-25%) tubulo-villous adenomas (5-10%)
All polyps ademoatous or villous need to be removed, how do we remove pedunculated polyps vs sessile polyps?
pedunculated polyps–> snared
sessile polyps–> usually need segmental colectomy for resection
What are the most common colonic polyps?
hyperplastic polyps
considered benign
This is an AD syndrome characterized by hamartomatous polyps of GI tract with hyper-pigmentation of buccal mucosa, lips, digits;
peutz-jeghers syndrome
due to mutation of tumor suppressor serine-threonine kinase 11 (STK11)
Peutz-Jeghers syndrome has what % risk of developing a GI cancer?
2-10 %
thus check the colon endoscopically Q 2 yrs
Screening for pts with FAP?
colonoscopy annually beginning at 10-12 yrs old
Screening for HNPCC?
C-scope every 2 yrs beginning at 20
anually after age 40 or 10 yrs younger earliest diagnosed relative
Most common form of colon cancer is ???
sporadic
Difference between melena and hematochezia?
melena is bright red blood in stool
hematochezeia is dark tarry blood in stool
Cancer on left side of colon present what type of sxs?
constrictive sxs–> change in bowel habits, constipation
Cancers on right side of colon present what type of sxs?
melena
fatigue assc with anemia
in advanced tumors–> abd pain
Gold standard to establish dx of colon cancer?
colonoscopy
How do we treat an obstructing cancer of right colon?
right colectomy
1 anastomosis between ileum and t-colon
Does presence of hepatic mets preclude excision of primary colon tumor?
no, the primary colon tumor should be removed
if hepatic dx is not extensive and mets to liver can be removed, pt would be cured
GOal of surgry for colon cancer?
remove the primary cancer w/good margins
regional lymphadenectomy
restoration of GI continuity
What is the procedure of choice for lesions involving the cecum, ascending colon and hepatic flexure?
right hemi-colectomy
(bowel is removed 4-6 cm proximal to ileo-cecal valve and carried up to tranverse colon section supplied by right branch of middle colic artery)
anastomosis created between ileum and T-colon
When do we perform an extended right hemi-colectomy for colon Ca?
procedure of choice for most tranverse colon lesions
right colic artery + middle colic artery divided at origin
right and tranverse colon removed
anastomosis created between terminal ileum and proximal left colon
When is a left-hemicolectomy performed?
for tumors of descending colon
resect from splenic flexure to rectosigmoid jxn
Most surgeons avoid incorporating the proximal sigmoid colon into an anastomosis, why?
tenuous blood supply from IMA
frequent involvement of sigmoid with diverticular dx
What is an abdominal colectomy (subtotal colectomy, total colectomy)?
entire colon removed from ileum to rectum
continuity preserved by an ileo-rectal anastomosis
What are the consequences of having a an abdominal colectomy (subtotal colectomy, total colectomy)?
entire colon removed from ileum to rectum
continuity preserved by an ileo-rectal anastomosis
(loss of absorptive and storage capacity of colon, so we see frequent loose stools)
(usually done in pts with multiple primary tumors and pts with HNPCC)
How do we stage colon cancer?
T–> penetration into bowel wall
N–> how many nodes involved
M–> distant mets or no
T stages of colon cancer;
Tis; Ca in situ, invasion of lamina propria
T1; invades submucosa
T2; invades muscularis propria
T3; invades THRU muscularis propria into pericolorectal tissue
T4a; penetrates to surfaces of visceral peritoneum
T4b; invades or adherent to other organs
N stages of colon cancer;
N0; no regional lymph node mets N1; 1-3 nodes N2; >4 nodes N2a; 4-6 nodes N2b; >7 nodes
M stages of colon cancer;
M0; no distant mets
M1; distant mets
Stages of colon cancer:
0--> Tis, N0, M0 1--> T1/T2, N0 M0 2a--> T3, N0, M0 2b--> T4a, N0, M0 2c--> T4b, N0, M0
4–> Any T, any M, M1
5 year survival rate of colorectal cancers?
Stage 1–> 90%
Stage 2–> 75%
Stage 3–> 50%
Stage 4–> < 5 %
During endovascular anuerysmal repair (EVAR), what artery is frequently covered in term of colonic arteries?
IMA
so you need to think about bowel ischemia
Most pts with UC see improvement of their extra-intestinal sxs after surgery, such as uveitis, arthritis, anemia, but om;y 50% of pts who have this manifestation see an improvement after colectomy;
pyoderma gangrenosum
ankylosing spondylitis + PSC do not improve
Absolute indications to take a pt to OR for c. diff colitis include?
toxic megacolon (cecal diamater > 12, colon diameter > 6 cm)
suspected bowel perforation
peritonitis
(relative indications; fulminant dx, failure of medial tx, worsening clinical course)
What is a Krukenberg tumor?
metastatic GI cancer to the ovaries
stomach is primary in 70% of time, next is colon, appendix, breast
In the emergent setting for a pt with c. diff colitis toxic megacolon, what procedure is done?
total abdominal colectomy with end ileostomy
You perform a sigmoidoscopy and find a colonic adenocarcinoma, what are the chances of pt having a synchronous lesion somewhere else along the colon?
3-5 %
Pts with large bowel obstructions typically presents with masses on what side of the colon?
left side
right colon usually has liquid stool
Preferred treatment for adjuvant treatment of colon cancers?
FOLFOX (fluoruracil, leucovorin, oxaliplatin)
given to pts with T3 or greater disease
any nodal mets
any distant mets
What part of the colon has the greatest risk of perforation for a large bowel obstruction in the rectum?
cecum (due to having large diameter, thus has greatest wall tension due to law of LaPlace)
What are some absolute contraindications to IPAA?
severe fecal incontinence
low rectal cancer involving the sphincters
perianal Crohn’s dx
What significantly increases the recurrence of diverticulitis?
colo-colonic anastomosis
when performing a sigmoidectomy for diverticulitis, the distal margin should be the rectum
When resecting suspected colonic cancer masses, how wide are the margins we need ?
5 cm proximally and distally
Most common complication of IPAA?
pouchitis (23-60%)
incontinence (17%)
stricture (11%)
This is a hereditary condition defined by the Amsterdam criteria;
Lynch syndrome- HNPCC
combo of cancer in colon, female GU tract, other sites
need 3 relatives with CRC (1 is a first degree relative of other two, >2 generations involved, >1 case appears before age 50)
Pts with personal hx of inflammatory dx should begin screening colonoscopy when?
8 yrs after onset of symptoms
Pts with Lynch syndrome (HNPCC), when should they be screened with colonoscopy?
age 20-25 or
10 years before youngest relative diagnosed with colon cancer
What is the sequence of gene loss in development of colo-rectal cancer?
mutated tumor suppressor APC gene–> allows accumulation of b-catenin, leads to increased cell signaling and proliferation
mutated k-ras oncogene–>uncontrolled cell growth
tumor suppressor p53 gene–> (normally arrests cell cylce in G/S phase to repair mutations, induces apoptosis when errors can’t be repaired)
Is flexible sigmoidoscopy sufficient to detect colon cancers?
40% of colon cancers are proximal to the area that can be visualized by flexible sig
Hematochezia, melena, anemia, are more common with right vs left colonic tumors?
right sided tumors
Change in bowel habits and suspected colonc cancer would be on left vs right?
left sided tumors
In terms of pedunculated vs sessile polyps, which ones have more malignant potential?
sessile
polyp size also a factor, smaller polyps less likely to harbor invasive cancer
For colon cancer, when do we perform adjuvant chemo?
all T3 or greater dx, any nodal mets, any distant mets
preferred use FOLFOX or CAPEOX (oxaliplatin, capecitabin)
What is stage I colon cancer and recommended treatment?
T1/T2
N0
M0
Tx–> RESECT
90% 5-year survival
What is stage II colon cancer and recommended treatment?
IIA; T3, N0, M0
Tx–> RESECT, Adjuvant chemo
IIB; T4, N0, M0
Tx–> Neoadjuvant chemo, resect if possible, adjuvant chemo
75% 5-year survival
What is stage III colon cancer and recommended treatment?
IIIA; T1/T2, N1, M0
Tx–> Resect, adjuvant therapy
IIIB; T3/T4, N1, M0
Tx–> Resect, adjuvant therapy
IIIC; any T, N2, M0
Tx–> Resect, adjuvant therapy
50% 5-year survival
What is stage IV colon cancer and recommended treatment?
IV; any T, any N, M1
Tx–> systemic therapy
< 5% 5-year survival
General principles of colon cancer resection based on location;
colectomy according to vascular supply with > 5 cm margins
regional lymphadenectomy w/specimen along origin of feeding vessel
restore GI continuity
When do we perform a right hemi-colectomy?
cancer of cecum, ascending, and hepatic flexure
ileum needs to be cut 4-6 cm proximal to ileo-cecal valve
consider middle colic artery L and R division when cutting tranverse colon
ileum anastomosed to t-colon
When do we perform a left hemi-colectomy?
cancers of descending colon
t-colon is divided proximal to splenic flexure
distal colon divided at rectosigmoid junction
t-colon anastomosed to rectum
After a tumor is resected or a diversion performed for obstruction symptoms what needs to happen next?
pt needs a c-scope to evaluate for synchronous lesions
How do we follow pts who have received treatment for colon cancer?
Stage 1; C-scope 1 year after surgery, advanced adenoma; c-scope in 1 year, not advanced, c-scope in 3 yrs
Stages II, III, IV; PE and CEA every 3-6 months for 2 yrs, then every 6 months for 5 yrs after
CT C/A/P every 6-12 months for for 5 yrs (3-6 months for stage IV)
How many lymph nodes are required for adequate staging of colon cancer?
at least 12
What is the recommended pre-op bowel prep and abx for elective colon cases?
mechanical bowel prep–> polyethylene glycol
PO abx–> erythromycin + neomycin
What are the principles of an ostomy creation?
protrude from skin
lie lateral and inferior to umbilicus
go thru rectus abdominis
pt should be able to visualize the stoma
obese pts need stoma above umbilicus
ostomy needs to be 4-5 cm free from all creases, folds, bony prominences
What is the ostomy triangle?
reasonable location for an ostomy;
ASIS, pubic tubercle, umbilicus
What;s better a hand-sewn or stapled anastomosis?
equal outcomes
When do we typically see anastomotic leaks?
after post-op day # 5
Long-term complications of a J pouch?
bowel frequency/urgency 8-10 a day
nocturnal incontinence
anal irritation
pouchitis
