Fiser- Ch 36&37: Colon, Rectum, Anus Flashcards
what marks the transition between anal canal and rectum?
levator ani muscle
main nutrient of colonocytes?
short chain fatty acids
layers of the colon: from lumen to exterior
- mucosa
- muscularis mucosa
- lymphatics
- submucosa
- muscularis propria
- subserosal connective tissue
what margin do you need for polypectomy of invasive cancer?
2mm
what can give a false positive guaiac stool test? 4
- beef
- iron
- vit c
- cimetidine
which organism infection is associated with colon cancer?
clostridium septicum
when do you perform an APR vs LAR in colon cancer?
you need at least 2cm margins, so if the cancer is within 2cm of the levator ani muscles, do an APR. otherwise LAR
T staging of colorectal cancer
T1 = submucosa T2 = muscularis propria T3 = into subserosa or through muscularis propria T4 = through the serosa
management of stage III colon cancer?
- nodes + or distant disease
- postop chemo, NO XRT
management of stage II and III rectal cancer
- NEOADJUVANT chemo and XRT
management of stage IV rectal cancer?
chemo and xrt, maybe not surgery unless just colostomy
what chemo is used in colorectal cancers?
FOLFOX
- 5FU
- Leucovorin
- Oxaliplatin
gene associated with FAP
APC, chromosome 5
autosomal dominant
management of patients with FAP?
total proctocolectomy, rectal mucosectomy, ileoanal pouch by age 20
what are the amsterdam criteria for lynch syndrome?
3,2,1:
at least 3 first degree relatives, over 2 generations, 1 cancer before age 50
treatment of sigmoid volvulus?
decompress with colonoscopy, give bowel prep then plan for sigmoid colectomy during that admission
treatment of cecal volvulus?
OR for right hemicolectomy, decompression w colonoscopy only works in 20% of pts
buzzword: creeping fat
crohns
buzzword: crypt abscesses
ulcerative colitis
buzzword: skip lesions
crohns
perforation with ulcerative colitis is most commonly where?
transverse colon
perforation with crohns disease is most commonly where?
distal ileum
management of low rectal carcinoids?
<2cm = wide local excision w negative margins
>2cm or invasion into muscularis propria: APR
management of colon or high rectal carcinoids?
<1cm = polypectomy >1cm = formal resection
treatment of ogilvie’s syndrome
initial: neostigmine, NGT, IVF
if colon >10cm, then decompression w colonoscopy and neostigmine
tagged RBC scan can pick up bleeding at what rate?
> 0.1cc/min
management of thrombosed hemorrhoids
Within 72 hours: elliptical excision
After 72 hours: lance open
difference between internal and external hemorrhoids?
above and below the dentate line
Management of rectal prolapse?
Altemeier: transanal perineal rectosigmoid resection if old and frail
LAR and pexy if in good condition
where are most anal fissures located?
posterior midline
what is the surgical treatment for anal fissure?
lateral subcutaneous internal sphincterotomy (DO NOT perform if 2/2 UC or Crohns)
whats goodsall’s rule?
anterior fistulas connect with the anus/rectum in a straight line
posterior fistulas go toward a midline internal opening in the anus/rectum
when can you perform wide local excision in an anal canal adenocarcinoma?
- Size <4cm
- <50% circumference
- T1 (limited to submucosa)
- Well differentiated
- No LVI/perineural invasion
whats the difference between anal margin and anal canal cancers?
anal canal is above the dentate line (SCC, adenoca, melanoma)
anal margin is below the dentate line (SCC, basal cell)
treatment of squamous cell carcinomas: anal canal vs anal margin
Anal canal (above dentate line) = nigro protocol Anal margin = WLE (if <5cm, need 0.5cm margin) or Chemo-XRT (5-FU and cisplatin)
nodal metastases: Superior and middle rectum: Lower rectum: Anal Canal: Anal Margin:
Superior and middle rectum: IMA nodes
Lower rectum: IMA and internal iliac nodes
Anal Canal: internal iliac nods
Anal Margin:inguinal nodes
what is Haggitt’s classification system for malignant polyps?
1: invading head
2: invade neck
3: invade stalk
4: invade base, bowel wall or sessile (require segmentectomy)
what is the most abundant bacteria in the flora of the normal colon?
bacteroides fragilis
what are indications for surgical management in massive GI bleeding?
transfuse >6 units PRBCs, ongoing hemodynamic instability
how to repair a parastomal hernia?
hernia repair with mesh! (lowest recurrence rate when fixed w mesh)
when is elective surgery indicated in the treatment of UC?
refractory to medical management, severe GI bleeding, if dysplasia is found on screening colonoscopy
what are the imaging modalities used to stage rectal cancer?
MRI or endoscopic US to eval depth of tumor and nodal involvement
what is nigro protocol used for?
squamous cell cancers of the anal canal
what is the neural control of the external anal sphincter?
voluntary control by branches of the internal pudendal and S4 nerves
treatment of cecal volvulus?
surgical resection: ileocolonic anastomosis unless perforation/gangrenous bowel
what are the criteria for candidates of transanal excision for rectal cancers? (5)
- Well differentiated T1 lesion
- <3cm in size
- < 30% circumference
- <8cm from anal verge
- No LVI or mucin production
what are the extraintestinal conditions associated with crohns? (5) and do each improve/not improve w colectomy?
- Arthritis- improves
- Ankylosing spondylitis- does not improve
- Erythema nodosum- resolves
- Pyoderma gangrenosum- improve
- PSC- does not improve
treatment of stage III colon cancer?
resection followed by FOLFOX: 5-FU, leucovorin, oxaliplatin
what are the 5 techniques for operative repair of internal hemorrhoids?
- Miligan-Morgan: excision of hemorrhoids and leaving wound open
- Ferguson: excision of hemorrhoids and closing wound
- Whitehead: circumferential excision just above the dentate line
- Stapled hemorrhoidectomy
- Transanal hemorrhoid dearterialization
colonocytes: secrete and absorb what electrolytes?
absorbs: water, sodium and chloride
secretes: potassium and bicarb
main energy source of colonocytes?
short chain fatty acids
name 3 short chain fatty acids
acetate, butyrate, propionate
