Fiser Chapter 36 COLORECTAL Flashcards
HNPCC patient gets CRC, what is tx?
Total proctocolectomy with the first cancer operation
50% get metachronous lesions within 10 years, often have multiple primaries
UC toxic colitis tx
NG tube, fluids, steroids, bowel rest, abx (cipro/flagyl)
50% need surgery
Avoid barium enemas, narcotics, anti-diarrheals, anti-cholinergics
Carcinoid of colon and rectum
Infrequent cause of carcinoid (15%)
Mets related to size of tumor
2/3 of colon carcinoids have either local or systemic spread
Tx: resect
Low rectal < 2 cm: wide local excision with negative margins
Low rectal > 2 cm or invasion of muscular propria: APR
Colon or high rectal: formal resection with adenectomy
Effect of radiation on CRC
When combined with chemo: decreases local recurrence and increases survival
Colonic obstruction causes
- Cancer
2. Diverticulitis
UC tx
Sulfasalazine or 5-ASA
Loperamide (avoid in toxic colitis)
Acute: steroids, consider cyclosporine or infliximab
APR side effects
Impotence and bladder dysfunction from injured pudendal nerves
Denonvilliers fascia
Anterior rectovesicular fascia (men) or rectovaginal fascia (women)
Pathology shows T2 lesion after transanal excision of rectal polyp, what is tx
APR or LAR
CRC main gene mutations
ADK53:
APC, DCC, K-ras, p52
Turcot’s syndrome
FAP with colon cancer and brain tumors
Inferior rectal artery comes off of what?
Internal budendal (off internal iliac)
Sigmoid volvulus risk factors
- High-fiber diets (Iran)
- Debilitated psychiatric patients, neurologic dysfunction, laxative abuse
Ogilvie’s treatment
Correct lytes (especially K), stop drugs that slow gut, NGT If colon >10 cm (high risk perf) -> decompress with colonoscopy and neostigmine, cecostomy if fails
Plicaue semilunares
Transverse bands that form haustra
Most common major morbidity after UC surgery with ileoanal anastomosis
Leak most common: drainage and abx
Infectious pouchitis: flagyl
Superior rectal artery comes off of what?
IMA
N staging for CRC
N: Negative nodes
N1: 1-3 nodes
N2: 4 or more nodes
N3: central nodes positive
Indications for surgery in diverticulitis
Total obstruction not resolved with medical therapy, perforation, or abscess formation not amenable to perc drainage, or inability to exclude cancer
-Resect all of sigmoid down to superior rectum
Causes of megacolon
Hirschprung’s: rectosigmoid most common, dx rectal biopsy
Trypanosoma cruzi: most common acquired cause, secondary to destruction of nerves
Azotemia after GI bleed
Caused by production of urea from bacterial action on intraluminal blood (increases BUN, also get increased total bili)
Watershed areas
Griffith’s (splenic flexure)
Sudeck’s (upper rectum where superior and middle rectal arteries join)
Amoebic colitis
Entamoeba histolytica from contaminated food and water with feces that contain cysts
Primary: colon
Secondary: liver
Risk factors: Mexico, EtOH
Symptoms: similar to US dysentery; chronic more common form (3-4 BMs/ day, cramping, fever)
Dx: endoscopy -> ulceration, trophozoites, 90% anti-amebic Abs
Tx: Flagyl, diiodohydroxyquin
Diverticula
Herniation of mucosa through colon wall at sites where arteries enter muscular wall, circular muscle thickens adjacent to diverticulum with luminal narrowing, present in 35% population
Caused by straining
Most occur on left side in sigmoid colon (80%)
Bleeding more likely with R sided
Diverticulitis more likely with L sided
MCC lower GI bleed
Diverticulosis bleeding: caused by disrupted vasa rectum, creating arterial bleeding, usually significant, 75% stops spontaneously, 25% recurs
APR indications
Malignant sigmoid or rectal lesions (not benign), that are not amenable to LAR (need at least 2 cm margin (2 cm from levator ani muscles), otherwise need APR)
Neutropenic typhlitis
Tx: abx, will improve when WBC increases
Surgery ONLY for free perf (not pneumatosis intestinalis)
Stump pouchitis
Diversion or disuse proctitis
Tx: Short-chain fatty acids
When is APR or LAR indicated (rather than transanal excision)?
Low rectal T2 or higher
UC characteristics
Mucosa and submucosa inflammation
Unusual to have strictures or fistulae
Spares anus: starts in rectum, contiguous
Bleeding, mucosal friability, pseudopolyps and collar button ulcers
Backwash ileitis possible
Crypt abscesses
Primary anastomosis in CRC resection
Most Right sided CRC can be primarily anastomosed without ostomy
What are features of increased cancer risk in polyps?
> 2 cm
Sessile
Villous
Best method of picking up CRC intrahepatic mets
Intraoperative US (3-5 mm resolution, better than CT/MRI/regular US)
Rectal vein drainage
Superior and middle into IMV (then PV)
Inferior into internal iliac vein and eventually IVC
Lower GI bleed with tufts and slow emptying on angiogram
Angiodysplasia: venous, usually R colon, usually less severe but more likely to recur than diverticular bleeds
20% have AORTIC STENOSIS, and usually gets better after valve replacement
Waldeyer’s fascia
Posterior rectosacral fascia
HNPCC cancer surveillance
Colonoscopy starting at age 25 or 10 years before primary relative go cancer
Also surveillance for other cancer types in family
Diverticulitis complications
Abscess: symptoms of obstruction, fluctuant mass, peritoneal signs, fever, wbc >20 -> percutaneous drainage
Colovesicular fistula: fecaluria, pneumouria, colovaginal fistula in women
Dx: cystoscopy best
Tx: Close bladder opening, resect involved colon, reanastomosis, diverting ileostomy, interpose omentum between bladder and colon
Crohn’s characteristics
Transmural inflammation
Granulomas
Fissures, fibrosis, fistulas, ulcers
Small bowel involvement
Skip lesions
Perianal disease, but rectum may be spared
Cobblestoning with long-standing disease
Fat wrapping
CRC chemo drugs
FOLFOX:
- 5-FU
- Leucovorin
- Oxaliplatin
CRC surveillance after treatment
Colonoscopy at 1 year, mainly to check for new primary (metachronous) colon cancer
Most common polyp
Hyperplastic
no cancer risk
Cecal volvulus tx
Can try to decompress with colonoscopy but unlikely to succeed (only 20%)
OR for Right hemicolectomy is best, can try cecopexy if colon viable and patient frail
What is the most important prognostic factor in CRC
Nodal status
UC surgical indications
- Massive hemorrhage
- Refractory toxic megacolon
- Acute fulminant UC, intractability
- Obstruction
- ANY dysplasia, cancer
- Systemic complications
- Failure to thrive
- Long standing disease >10 years
- Prophylaxis against colon CA (controversial)
Contraindications for colonoscopy
Recent MI
Splenomegaly
Pregnancy (if fluoroscopy planned)
Most common site of primary CRC
Sigmoid
CRC liver metastasis 5-year survival?
35% if resectable leaving adequate liver function
Pathology shows T1 lesion after transanal excision of rectal polyp, what is tx
Transanal excision adequate if margins clear (2 mm), well differentiated, has no lymphovascular invasion
Most common neoplastic polyp
Tubular adenoma, generally pedunculated
Intestinal wall layers
- Serosa
- Muscularis propria: circular muscle
- Submucosa
- Mucosa (columnar epithelium): muscularis mucosa is small muscle layer below mucosa above basement membrane
Infections causing colitis
- Salmonella
- Shigella
- Campylobacter
- CMV
- Yersinia (fecal-oral, can mimi appendicitis, tx tetracycline or Bactrim)
- Viral
- Giardia
Bloody diarrhea, abdominal pain, fever, weight loss
UC
Preoperative chemoradiation before APR?
Produces complete response in some patients
Might help preserve sphincter function
-May help shrink rectal tumors, allowing down-staging of the tumor and possibly allowing LAR versus APR
LLQ pain, tenderness, fever, leukocytosis
Diverticulitis: mucosal perf with adjacent fecal contamination, denotes infection and inflammation of colonic wall and surrounding tissue
Dx: CT scan only if worried abut complications
Follow-up colonoscopy to r/u cancer
Tx: levofloxacin/flagyl, 3 days bowel rest, outpatient if mild
Distal margin in colon resection for diverticulitis
Normal rectum
Main nutrient of colonocytes
Short-chain fatty acids
Polypectomy shows T1 leasion, what is tx
Polypectomy adequate if margins clear (2 mm), well differentiated, has no lymphovascular invasion
Otherwise need formal resection
25yo presents obstructed with dilated cecum in RLQ
Cecal volvulus
UC surgery
Total proctocolectomy, bring up ileostomy and connect later if emergent
If elective: Rectal mucosectomy, J-pouch, low rectal ILEOANAL ANASTOMOSIS with temporary diverting ileostomy while pouch heals. Can also perform APR with ileostomy.
Risk factors for CRC (colorectal cancer)
Red meat and fats (O2 radicals)
Clostridium septicum association
T staging for CRC
T1: into submucosa
T2: into mucularis propria
T3: into serosa (or through MP if no serosa)
T4: into free peritoneal cavity or other organs
When do polyps start in FAP?
Puberty
Colonic wall plexi
Outer: Auerbach’s
Inner: Meissner’s
MCC of death in FAP following colectomy
Periampullary tumors of the duodenum
CRC lung metastasis 5-year survival?
25% in selected patients after resection
Middle rectal artery comes off of what?
Internal iliac: during LAR or APR, the lateral stalks contain the middle rectal arteries
Cecal mass/abscess with fistula, path shows yellow-white sulfure granules
Actinomyces: suppurative and granulomatous, cecum most common location, can be confused with CA
Tx: PCN, tetracycline, abscess drainage
Watery, green, mucoid diarrhea with pain and cramping, occurring 3 weeks after abx
C diff
Tx: PO vanc or flagyl, or IV flagyl, +/- lactobacillus
Risk of local recurrence in rectal versus colon cancer
Higher in rectal
Key finding in C diff pseudomembranous colitis
PMN inflammation of mucosa and submucosa, pseudomembranes, plaques, ringlike lesions in distal colon
Abdominal pain, bright red bleeding, endoscopy shows cyanotic edematous mucosa covered with exudates
Ischemic colitis: low-flow state (recent MI, CHF), ligation of IMA at surgery (AAA repair), embolus or thrombosis of IMA, sepsis
Use of rectal US in rectal cancer
Assessing depth of invasion (sphincter involvement), recurrence, presence of enlarged nodes
Need total colonscopy to r/o synchronous lesions
Gardner’s syndrome
FAP with colon cancer and desmoid tumors/osteomas
What is associated with the worst prognosis in CRC?
Mucoepidermoid type
APR
Abdominoperineal resection
- Rectum, anal canal excised
- Permanent colostomy placed
When is polpectomy enough for invasive carcinoma?
Polypectomy is adequate treatment for invasive carcinoma only if margin is at least 2 mm, not poorly differentiated, and no e/o venous or lymphatic invasion
UC extraintestinal manifestations
- Failure to thrive in kids is most common extraintestinal manifestation requiring total colectomy
- PSC (risk continues after colectomy)
- Ankylosing spondylitis (risk continues after colectomy)
- Pyoderma gangrenosum
- HLA B27: sacroiliitis, AS, UC
- Thromboembolism
Colon cancer screening options
- Colonoscopy every 10 years, or
- High-sensitivity fecal occult blood test every 3 years and flex sig every 5 years, or
- High-sensitivity fecal occult blood testing annually, or
- Double contrast barium enema or CT colonography every 5 years
Surveillance in patients with suspected FAP
Flexible sigmoidoscopy (do NOT need colonoscopy)
Also endoscopy every 2 years to check for duodenal polyps
Where are most polyps found?
Left side
What is associated with an improved prognosis in CRC?
Lymphocytic penetration
Tx of isolated liver or lung mets in CRC?
Resection
What layer of colon wall does 80% of blood flow go?
Mucosa and submucosa
What marks the transition between the rectum and anal canal?
Levator ani (which then becomes external sphincter)
Goals of resection in CRC
En bloc
Adequate margins (2 cm)
Regional adenectomy
Infectious pouchitis
Tx: metronidazole
Crypts of Liberkuhn
Mucus-secreting goblet cells
Amount of bleeding needed for arteriography and tagged RBC scan
Arteriography: at least 0.5 cc/min
Tagged RBC: at least 0.1 cc/min
External and internal sphincters
External (puborectalis): continuation of levator ani, voluntary control
Internal pudendal nerve, inferior rectal branch
Internal sphincter: continuation of muscularis propria, smooth muscle, involuntary, normally contracted
Most likely polyp to produce symptoms
Villous adenoma, generally sessile and larger
50% have cancer in them
Indications for APR
Rectal pain with rectal cancer
UC toxic megacolon definition
Toxic colitis plus distension, abdominal pain, tenderness
What portions of colon are retroperitoneal?
Ascending, descnending, sigmoid
Peritoneum covers anterior upper 2/3 of rectum
What can cause a false-positive quaiac?
Beef
Vitamin C
Iron
Cimetidine
IBD perforation location
UC: transverse colon more common
Crohn’s: distal ileum most common
AXR shows bent inner tube sine, gastrografin enema shows bird’s beak sign
Sigmoid volvulus
When can you do transanal excision of low rectal cancer rather than APR or LAR?
T1 (limited to submucosa)
< 4 cm
Well differentiated
Negative margins (need 1 cm)
No neurologic or vascular invasion
UC cancer risk and screening
In patients with pancolitis, starting 10 years after diagnosis, 1% per year
- Cancer evenly distributed throughout colon
- Need yearly colonoscopy starting 8-10 years after diagnosis
Surveillance after UC surgery
Lifetime surveillance of residual rectal area. Many ileoanal anastomoses need resection d/t/ cancer, dysplastic changes, refractory pouchitis, of pouch failure (incontinent)
Taenia coli
3 bands that run longitudinally along colon
At rectosigmoid junction become broad and completely encircle bowel
CRC disease spread
- Nodes first (nodal status most important prognostic factor)
- Liver via PV (number 1 site of mets)
- Lungs via iliac vein (number 2 site of mets)
- Ovaries
- Spine via Batson’s plexus (in RECTAL not colon cancer)
- Adjacent organs
(generally not to bone)
Definition of invasive carcinoma
If goes through basement membrane below muscularis mucosa, into submucosa. If just into muscularis mucosa, is intramucosal cancer
When is chemo/radiation indicated for CRC?
Colon cancer:
Stage 3 or 4 (positive node or distant mets): postop chemo only
Rectal cancer:
Stage 2 and 3 rectal cancer (T3 or nodes): pre-op chemoradiation
Stage 4: chemo and radiation +/- surgery
Diverticulosis bleeding dx and tx
Dx: NG tube to rule out upper GIB, colonoscopy
- If massive with hypotension and tachy: Angio
- If hypotensive and not responding to resusc: OR
- Intermittent bleeds hard to localize: tagged RBC scan
Tx:
- Colonoscopy
- Arteriography with vasopressin or highly selective coild embolization
- Segmental colectomy (or subtotal colectomy if cannot identify site)
Colon cancer screening should start at what age?
50 for normal risk
10 years before or at age 40 for intermediate risk (family history)
Extensive low rectal villous adenomas with atypia, what is tx
Transanal excision, can try mucosectomy, as much of polyp as possible
NO APR UNLESS CANCER PRESENT
FAP treatment
Total colectomy prophylactically at age 20: proctocolectomy, rectal mucosectomy, and ileoanal pouch (J-pouch), or
Total proctocolectomy with end ileostomy
Then lifetime surveillance of residual rectal mucosa
Vascular supply of colon
SMA (ileocolic, right and middle colic arteries): ascending and 2/3 transverse colon
IMA (left colic, sigmoid branches, superior rectal): 1/3 transverse, descending colon, sigmoid, upper rectum
Marginal artery: connects SMA to IMA, providing collateral flow, runs along colon margin
Arc of Riolan: short direct connection between SMA and IMA
Colon inertia
Slow transit time; may need subtotal colectomy
Performing appy and get in there and find out its actually R sided diverticulitis, what is tx
Right hemicolectomy
Gangrenous ischemic colitis tx
OR for sigmoid resection or left hemicolectomy
Colon electrolytes
Secretes K
Reabsorbs Na and H2O
Which nerves are parasympathetic and sympathetic?
Pelvic splanchnics: parasympathetic
Lumbar and scaral plexus: sympathetic
M staging for CRC
M1: distant mets
Automatically become stage IV
Venous drainage of colon
Follows arterial except IMV, which goes to splenic. Splenic vein joins SMV to form PV behind the pancreas
HNPCC (Lynch syndrome) genetics
Autosomal dominant
5% of population
DNA mismatch repair
Predilection for right-sided and multiple cancers
Ogilvie’s syndrome
Pseudoobstruction, associated with opiates, bedridden or older patients, recent surgery, infection or trauma
Massively dilated colon which can perforate
Lymphatic drainage of rectus
Superior and middle into IMA nodal lymphatics
Lower into IMA and internal iliac nodes
UC changes on barium enema
Loss of haustra, narrow caliber, short colon, loss of redundancy (avoid in toxic colitis)
Sigmoid volvulus tx
Colonoscopy to decompress (80% reduce, 50% will recur)
Sigmoid colectomy during same admission
If gangrene or peritonitis: OR for sigmoidectomy
Incidence of CRC recurrence
20%, usually within 1 year
5% get another primary, which is the main reason for surveillance colonoscopy
Endoscopic or surgical removal of polyp?
Generally can remove pedunculated polyps endoscopically. If cannot remove whole polyp (more common with sessile), need segmental resection
Watershed areas of colon
Splenic flexure (Griffith’s point): SMA and IMA junction
Rectum (Sudak’s point): Superior rectal and middle rectal junction
Overall, colon is more sensitive to ischemia than small bowel d/t less collaterals
Amount of blood needed to see melena
50 cc
FAP genetics
APC gene on chromosome 5
Autosomal dominant, all have cancer by age 40
20% are spontaneous
Lynch I versus II
Lynch I: just colon CA risk
Lynch II: also risk of ovarian, endometrial, bladder, stomach cancers
UC toxic colitis definition
> 6 bloody stools/day, fever, tachy, Hgb drop, leukocytosis
Amsterdam criteria for HNPCC
“3, 2, 1”
At least 3 first degree relatives
Over 2 generations
1 with cancer before age 50
Radiation damage in CRC
Usually rectal injury
Vasculitis, thrombosis, ulcers, strictures
