-
4 layers of colon wall
mucosa, submucosa, muscularis propria, serosa
-
portions of rectum covered in peritoneum
anterior upper and middle 1/3
-
circular/longitudinal interwoven inner layer of colon
muscularis mucosa
-
circular layer of muscle
muscularis propria
-
transverse bands of colon that form haustra
plicae semilunaris
-
three bands that run longitudinally along colon
taenia coli
-
approximate distance of dentate line from anus
2cm
-
approximate distance of the anorectal ring from the anal verge
4cm
-
vascular supply of ascending and 2/3 transverse colon
SMA (ileocolic, right colic, middle colic)
-
Vascular supply of 1/3 transverse, descending, sigmoid colon and upper rectum
IMA (left colic, sigmoid branches, superior rectal)
-
Artery that runs along the colon to connect SMA to IMA for collateral flow
Marginal artery
-
Short direct connection between SMA and IMA
Arc of Riolan
-
Origin of superior rectal artery
IMA
-
Origin of middle rectal artery
Internal iliac
-
Origin of inferior rectal atery
Internal pudendal
-
Lymphatic drainage of superior and middle rectum
IMA nodal lymphatics
-
Lymphatic drainage of lower rectum
IMA nodes, internal iliac nodes
-
Watershed area of SMA and IMA junction near splenic flexure
Griffith�s point
-
Watershed area of rectum, where superior rectal and middle rectal veins join
Sudak�s point
-
Anal sphincter under CNS control, innervated by pudendal and S4
External sphincter
-
Anal sphincter under involuntary control, continuation of circular band of colon and tonically contracted
Internal sphincter
-
Inner nerve plexus
Meissner�s
-
Outer nerve plexus
Auerbach�s
-
Distance of anal canal (from verge)
0-5cm
-
distance of rectum (from anal verge)
5-15cm
-
marker of transition between anal canal and rectum
levator ani
-
mucus secreting goblet cells in rectum
crypts of Lieberkuhn
-
squamocolumnar junction at anal verge
dentate line
-
main nutrient of colonocytes
short-chain fatty acids
-
treatment of infectious pouchitis
Flagyl
-
Rectovesicular fascia in men (rectovaginal fascia in women)
Denonvillier�s fascia
-
Rectosacral fascia
Waldeyer�s fascia
-
Most common type of polyp (no cancer risk)
Hyperplastic polyp
-
Most common intestinal neoplastic polyp
Tubular adenoma
-
Most symptomatic polyp
Villous adenoma
-
% of villous adenoma that have cancer
50
-
% of patients >50 with guiac positive stools that have cancer
30
-
layer a dysplastic lesion must grow into to be considered invasive (in colon)
submucosa
-
normal screening for colon cancer
flex sig q3-5y + stool guiac q1y, OR colonoscopy q10y + stool guiac q1y
-
causes of false positive guiac
beef, vitamin C, iron, antacids, cimetidine
-
margins required for T1 lesion removed by colonoscopy or transanal excision
2mm
-
margins required for T2 lesion removed by transanal excision
much larger (APR needed)
-
main gene mutations in colon ca (4)
APC, DCC, p53, k-ras
-
Most important prognostic factor in colon cancer
Nodal status
-
Most common site of metastasis in colon cancer
Liver (then lung)
-
Route of direct metastasis of rectal cancer to spine
Batson�s plexus
-
Subtype of colon cancer with worst prognosis
Mucoepidermoid
-
Margins required in colon cancer resection
2cm
-
best method of picking up intrahepatic mets
intraoperative ultrasound
-
best method to assess depth of invasion and nodal status
rectal ultrasound
-
reasons to do APR in patient with unresectable metastases
pain, bleeding
-
reasons to do an ostomy + mucus fistula in patient with unresectable metastases
obstruction
-
depth of invasion of T1 lesions
submucosa
-
depth of invasion of T2 lesions
into muscularis propria
-
depth of invasion of T3 lesions
into serosa (through muscularis if no serosa present)
-
depth of invasion of T4 lesions
through serosa or into adjacent organs/structures
-
N staging of colon cancer
N0 (no nodes), N1 (1-3 nodes), N2 (4+ nodes)
-
Rectal cancers needing XRT
T3 or greater, or positive nodes
-
Side effects of XRT (4)
Vasculitis, thrombosis, ulcer, stricture
-
% of patients with a synchronous primary lesion at time of first cancer
5
-
% recurrence rate of colorectal cancer
20
-
followup for colon cancer (postop)
CEA, stool guiac q6m X3 years, then annually. Annual colonoscopy
-
Autosomal dominant genetic defect predisposing to colon cancer
FAP
-
Treatment of FAP patients
Prophylactic total colectomy at age 20
-
Locations of polyps in patients with FAP (2)
Colonic, duodenal
-
Genetic defect associated with colon cancers and desmoid tumors/osteomas
Gardner�s syndrome
-
Genetic defect associated with colon cancers and brain tumors
Turcot�s syndrome
-
Autosomal dominant defect associated with DNA mismatch repair gene, predisposes patients to colon cancer
Lynch syndromes (hereditary nonpolyposis colon cancer)
-
At least 3 1st degree relatives, over 2 generations, 1 with cancer before age 50
Amsterdam criteria (consideration for lynch syndromes)
-
Other cancer types found as part of Lynch II syndrome (4)
Ovarian, endometrial, bladder, stomach
-
Syndrome where hamartomatous polyps develop, and cancer risk is increased
Juvenile polyposis
-
GI hamartoma polyposis and dark pigmentation around mucous membranes
Peutz-Jeghers
-
Syndrome of hamartomatous polyps (no malignant potential), nail/hair atrophy, and hypopigmentation
Cronkite-Canada syndrome
-
Treatment of sigmoid volvulus
Colonoscopic decompression, sigmoid resection during same admission
-
Treatment of cecal volvulus
Right hemicolectomy
-
Layers of colon involved in UC
Mucosa, submucosa
-
Area of GI tract almost always involved in UC
Rectum
-
Anal involvement in UC?
No (typically spares anus)
-
Hallmarks of UC seen on colonoscopy (3)
Mucosal friability, pseudopolyps, collar button ulcers
-
Findings of UC on barium enema (3)
Loss of haustra, narrow-caliber, short colon, loss of redundancy
-
Common site of colonic perforation in UC
Transverse colon
-
Common site of perforation in Crohn�s
Distal ileum
-
Surgical indications for UC (9)
Hemorrhage, toxic megacolon, acute fulminant UC, obstruction, dysplasia, cancer, intractability, failure to thrive, longstanding (>10y) disease
-
Most common major morbidity after colon surgery
Leak
-
Cancer risk with UC
1-2% per year starting 10years after diagnosis
-
HLA type associated with sacroiliitis and ankylosing spondylitis
B27
-
Conditions that improve following colectomy for UC (3)
Ocular problems, arthritis, anemia
-
Conditions that do not improve following colectomy for UC (2)
PSC, ankylosing spondolytis
-
Most common area of colon perforation after obstruction
Cecum
-
Common causes of colonic obstruction
Cancer, diverticulitis
-
Air in bowel wall associated with ischemia
Pneumotosis intestinalis
-
Pseudoobstruction of colon associated with opiate use, bedridden patients, recent surgery, infections or trauma
Ogilvie�s syndrome
-
Treatment of Ogilvie�s syndrome
Colonoscopic decompression, neostigmine, cecostomy if refractory
-
Sites of infection of entamoeba histolytica (2)
Colon (primary), liver (secondary)
-
Risk factors for entamoeba histolytica (3)
Travel to Mexico, ETOH, fecal-oral transmission
-
Treatment of entamoeba histolytica
Flagyl,diiodohydroxyquin
-
Most common site for actinomyces
Cecum
-
Treatment of actinomyces
Tetracycline or PCN, drainage
-
Proctitis, tenesmus, bleeding caused by chlamydia
Lymphogranuloma venereum
-
Herniation of mucosa through colon wall at sites where arteries enter muscular wall
Diverticuli
-
Most common symptom of right-sided diverticuli
Bleeding
-
Most common symptom of left-sided diverticuli
Obstruction, infection
-
Passage of tarry stools
Melena
-
Cause of azotemia after GIB
Production of urea from bacterial breakdown of intraluminal blood
-
Rate of bleed visible on arteriography
>0.5cc/min
-
rate of bleed visible on tagged RBC scan
>0.1 cc/min
-
perforation in colonic mucosa with adjacent fecal contamination
diverticulitis
-
complications of diverticulitis
abscess, obstruction, free perforation
-
treatment of uncomplicated diverticulitis
flagyl/cipro, bowel rest
-
indications for surgery for diverticulitis
recurrent disease (2nd or more attack), obstruction, perforation, abscess, inability to exclude cancer
-
disease presenting with fecaluria, pneumonuria
colovesicular fistula
-
most common cause of lower GI bleed
diverticulosis
-
% of diverticular bleeds that stop spontaneously
75
-
first treatment of massive lower GI bleed
angio to localize, then OR if unstable or recurrent bleeding
-
less severe lower GIB but more likely to be recurrent
angiodysplasia
-
% of patients with angiodysplasia that have aortic stenosis
20-30%
-
areas of colon most vulnerable to low-flow states
splenic flexure and descending colon
-
junction of superior rectal and middle rectal arteries
Sudack�s point
-
Causes of ischemic colitis
Low flow state, ligation of IMA, embolus/thrombosis of IMA
-
Disease with pseudomembranes, plaques, ringlike lesions seen in colon
C. difficile colitis
-
Enterocolitis often following chemotherapy; pneumotosis is common
- Neutropenic typhlitis
- Treatment of neutropenic typhlitis
- Antibiotics. Improvement occurs when WBCs increase
-
Bacterial infection that can mimic appendicitis in children
Yersinia
-
Most common area for Hirschprung�s
Rectosigmoid
-
Most common acquired cause of Hirschprung�s
Trypanosoma cruzi (destroys nerves)
|
|
