Colorectal Flashcards
Colon secretes ___ and re-absorbs ____; mostly in the R colon and cecum
Secretes K; reasorbs Na and water
4 layers of colon mucosa
Mucosa (columnar epithelium); submucosa, muclaris propria, serosa
Asc/Dec, sigmoid colon are – intra/retroperit
Retroperitoneal
Ascending and 2/3 of transverse colon are supplied by…
SMA (ileocolic, right and middle colic arteries)
1/3 of transverse, descending colon, sigmoid colon and upper rectum are supplied by…
IMA
What is arc of Riolan
Short direct connection between SMA and IMA
80% of blood flow in colon goes to which bowel layers?
Mucosa, submucosa
Splenic vein joins the ***
SMV to form the portal vein behind the pancreas
IMV drains into…
Splenic vein
The superior / middle / inferior rectal arteries
Superior: branch of IMA
Middle: branch of II (lateral stalks during LAR or APR contain middle rectal arteries)
Inferior: branch of internal pudendal – branch of II
Where do the superior and middle rectal veins drain? What about inferior?
IMV –> portal vein
Inferior: internal iliac, caval
Watershed areas of colon
Splenic flexure (Griffith’s point) – SMA/IMA junction
What is Sudak’s point?
Rectum – superior and middle rectal junction
Is colon or small bowel more sensitive to ischema/low-flow states?
Colon; fewer collaterals
External sphincter
Inferior rectal branch of internal puddendal nerve (continuation of levator ani muscle)
Internal sphincter
Involuntary / pelvic splanchnic nerves; continuation of muscularis propria; normally contracted
Meissner’s vs. Auerbach’s plexus
Meissners: inner nerve plexux
Auerbach: Outer nerve plexus
Pelvic splanchnic: sympa or para
Para
Distance from anal verge to anal canal, rectum, recto-sigmoid junction
Anal canal: 0-5 cm
Rectum: 5-15 cm
Recto-sigmoid: 15-18cm
Transition between anal canal and rectum
Levator ani
What are crypts of Lieberkuhn?
Mucin-secreting goblet cells
Treatment of colonic intertia
Subtotal colectomy
Main nutrient of colonocyte
SCFA
What is treatment for stump pouchitis
SCFA enema
Treatment of infectious pouchitis
Flagyl
Denovilliers vs Waldeyers fasica
Anterior/Posterior
MC colon polyp
Hyperplastic; no cancer risk
MC neoplastic polyp in colon
Tubular adenoma
MC colon polyp to produce symptoms
Villious adenoma; 50% have cancer
Characteristics of colon polyps with increased cancer risk
> 2cm, sessile, villous
If a polyp cannot be resected endoscopically, how do you get rid of it?
Segmental resection
Invasive colon cancer has eroded into…
Submucosa
Normal age for colon cancer screening
50 at normal risk; 40, or 10 years before youngest case
Colon cancer screening
q 10 year cscope
high-sensitivity FOBT q 3 years and flex sig q 5
Q annual fecal occult blood
When is a polypectomy sufficient treatment?
t1; clear margins 2mm, well-differentiated, no vasc/lymphatic invasion; otherwise formal resection
T/F Red meat and fat are risk factors for colon cancer
True / oxygen radicals
Main genetic mutations of colon cancer
APC, DCC, p53, k-ras
Most common site of colon cancer
Sigmoid colon
Where does colon cancer spread first?
Nodes
1 site of colon cancer mets
Liver; Number 2 is lung
How does colon cancer get to liver, lung?
Liver: PV
Lung: Iliac vein
T/F isolated liver, lung mets can be resected for colon ca
True
How does rectal cancer mets to the spine?
Batson’s venous plexus
Can colon cancer be resected en bloc?
Yes
T/F Mucoepidermoid colon cancer has worst prognosis
True
Best test for depth, invasion; recurrence, nodes
Trans-rectal ultrasound
For rectal pain with rectal cancer — treatment
APR
What size margins for colon cancer
2cm
Best method of picking up intra-hepatic mets
Intra-operative ultrasound (3-5 mm)
What is an APR
Permanent colostomy; anal canal is excised with the rectum
- Impotence, bladder dysfunction (injured pudendal nerves)
If you cannot get 2cm margins with an LAR, the treatment is…
APR
Neoadjuvant Chemo-RT for rectal cancer
Can produce complete response, preserve sphincter function
t1 vs t2 vs t3 vs t4 colon ca
submucosa, muscularis propria, subserosa, through serosa
Can low recta T1’s be excised transanally
Yes; negative margins, well-differentiated
Who gets NAC/RT colon cancer
Stage 2, 3
Chemo for colon cancer
FOLFOX (5-FU, leucovorin, oxaliplatin)
Most common site of injury in colon cancer RT
Rectum; vasculitis, thrombosis, ulcers, strictures, bleeding
Is FAP AD?
Yes
When are polyps present in FAP?
Puberty
When do you get a total colectomy in FAP?
Age 20
Where else can you get polyps in FAP?
Duodenum
MCC death in patients with FAP who have undergone colectomy?
Peri-ampullary tumors of duodenum
What is Gardner’s syndrome?
Colon Cancer (a/w APC gene) and intra-abdominal desmoid tumors/osteomas
What is Turcot’s syndrome?
APC gene, brain tumors
Lynch syndrome
5% population; AD
- A/W DNA MMR gene
Lynch II syndrome also increases risk of…
Ovarian, endometrial, bladder, stomach
What operation do you need for Lynch syndrome?
Total proctocolectomy with first cancer operation
Lynch L or R sided cancer
R
When does surveillance colonoscopy begin for Lynch?
25 or 10 years before primary relative
For HNPCC, do you need colonoscopy?
No; flex sig
Sigmoid volvulus is more common with low or high fiber diet
High fiber
In what types of patients is sigmoid voluvlus more common
Psychiatric, neurologic dysfunction, laxitive absue
Treatment for sigmoid voluvlus
Decompress with colonscopy; bowel prep, and perform sigmoid colectomy during same admission
Cecal volvulus
Can appear as SBO; R hemi colectomy; can try cecopexy is colon is viable and patient is frail
UC involves which bowel layers
Mucosa and submucosa
Does UC spare anus?
Yes
Crypt abscess in UC or Crohn’s
UC
Pseudo-polyps UC or Crohn’s
UC
Cobblestoning in UC vs. Crohn’s
Crohn’s
In UC, bleeding is universal and has mucosal friability with pseudopolyps
True
Medical treatment of UC
Salfasalazine, Liperamide
For acute flares of UC
Steroids; Cipro/Flagyl
Indications for surgery with toxic colitis and toxic megacolon
Pneumoperitoneum, diffuse peritonitis; uncontrolled sepsis, major hemorrhage
Perforation with UC vs. Crohn’s
Transverse colon: UC
Crohn’s distal ileum
Risk of cancer in UC
1%/year starting 10 years after initial diagnosis
MC extra0intestinal manifestation in children
FTT
Treatment poyderma gangrenosusm
Steroids
< 2 cm low rectal carcinoid
WLE with negative margins
> 2 cm rectal carcinod or invasion into muscularis propria
APR
Most likley location colon perf with obstruction
Cecum
Number 1 and 2 cause of colonic obstruction
Cancer, diverticulitis
What is Ogilvie’s syndrome
Massively dilated colon which can perforatea
Treatment Ogilvie’s syndrome
Replace electrolytes, discontinue anti-motility agents, i.e. Morphine; NGT, neostigmine
If colon > 10 cm in Ogilbie’s syndrome
Decompression with colonscopy and neostigmine, cecostomy if that fails
Treatment of amoebic colitis
Flagyl (colon –> liver)
* Mexico, fecal-oral
Actinomyces most common location
Cecum
Yellow-white sulfer granules
Actinomces – penicillin
Tagged RBC scan vs. arteriography for LGI bleed
> 0.1 cc/min; >0.5cc/min
MCC complication following diverticulitis
Abscess
Need to resect all of sigmoid colon down to superior rectum for diverticulitis
True
MCC colo-vesicular fistula
Diverticulitis
Best test of colo-vesicular fistula
Cystoscopy
Vessels that bleed in diverticulosis
Vasa rectum; arterial bleeding
Usual first step for diverticular bleed
Colonoscopy
If massive LGI bleed
Angiography; to localize area for surgery; or highly selective coil embolization
Most sensitive test for LGI bleed
Tagged RBC scan
Angiodysplasia bleeding is typically on L or R colon
R; venous bleeds
T/F 20% patients with angiodysplasia have AS
True
Usually ischemic colitis involves R or L colon
L
SMA/IMA junction
Grifftith’s point
When to perform a colon resection for ischemic colitis
Gangrenous colitis; peritonitisl black bowel; sepsis; perforation
* Otherwise NPO/ABX/IVF
Key histologic finding for C. diff colitis
PMN inflammation of mucosa and submucosa
Neutropenic typhlitis (enterocolitics)
Follows CTX with WBC low (nadir); can mimic surgical disease; can see pneumatosis intestinalis; surgery only for free perforation. Treatment is abx
Can Yersinia mimic appendicitis
Yes
MCC of acquired megacolon?
Trypanosoma cruzi (2/2 destruction of nerves)
