Fiser- Ch 36&37: Colon, Rectum, Anus Flashcards Preview

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Flashcards in Fiser- Ch 36&37: Colon, Rectum, Anus Deck (52)
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1
Q

what marks the transition between anal canal and rectum?

A

levator ani muscle

2
Q

main nutrient of colonocytes?

A

short chain fatty acids

3
Q

layers of the colon: from lumen to exterior

A
  1. mucosa
  2. muscularis mucosa
  3. lymphatics
  4. submucosa
  5. muscularis propria
  6. subserosal connective tissue
4
Q

what margin do you need for polypectomy of invasive cancer?

A

2mm

5
Q

what can give a false positive guaiac stool test? 4

A
  1. beef
  2. iron
  3. vit c
  4. cimetidine
6
Q

which organism infection is associated with colon cancer?

A

clostridium septicum

7
Q

when do you perform an APR vs LAR in colon cancer?

A

you need at least 2cm margins, so if the cancer is within 2cm of the levator ani muscles, do an APR. otherwise LAR

8
Q

T staging of colorectal cancer

A
T1 = submucosa
T2 = muscularis propria
T3 = into subserosa or through muscularis propria
T4 = through the serosa
9
Q

management of stage III colon cancer?

A
  • nodes + or distant disease

- postop chemo, NO XRT

10
Q

management of stage II and III rectal cancer

A
  • NEOADJUVANT chemo and XRT
11
Q

management of stage IV rectal cancer?

A

chemo and xrt, maybe not surgery unless just colostomy

12
Q

what chemo is used in colorectal cancers?

A

FOLFOX

  • 5FU
  • Leucovorin
  • Oxaliplatin
13
Q

gene associated with FAP

A

APC, chromosome 5

autosomal dominant

14
Q

management of patients with FAP?

A

total proctocolectomy, rectal mucosectomy, ileoanal pouch by age 20

15
Q

what are the amsterdam criteria for lynch syndrome?

A

3,2,1:

at least 3 first degree relatives, over 2 generations, 1 cancer before age 50

16
Q

treatment of sigmoid volvulus?

A

decompress with colonoscopy, give bowel prep then plan for sigmoid colectomy during that admission

17
Q

treatment of cecal volvulus?

A

OR for right hemicolectomy, decompression w colonoscopy only works in 20% of pts

18
Q

buzzword: creeping fat

A

crohns

19
Q

buzzword: crypt abscesses

A

ulcerative colitis

20
Q

buzzword: skip lesions

A

crohns

21
Q

perforation with ulcerative colitis is most commonly where?

A

transverse colon

22
Q

perforation with crohns disease is most commonly where?

A

distal ileum

23
Q

management of low rectal carcinoids?

A

<2cm = wide local excision w negative margins

>2cm or invasion into muscularis propria: APR

24
Q

management of colon or high rectal carcinoids?

A
<1cm = polypectomy
>1cm = formal resection
25
Q

treatment of ogilvie’s syndrome

A

initial: neostigmine, NGT, IVF

if colon >10cm, then decompression w colonoscopy and neostigmine

26
Q

tagged RBC scan can pick up bleeding at what rate?

A

> 0.1cc/min

27
Q

management of thrombosed hemorrhoids

A

Within 72 hours: elliptical excision

After 72 hours: lance open

28
Q

difference between internal and external hemorrhoids?

A

above and below the dentate line

29
Q

Management of rectal prolapse?

A

Altemeier: transanal perineal rectosigmoid resection if old and frail
LAR and pexy if in good condition

30
Q

where are most anal fissures located?

A

posterior midline

31
Q

what is the surgical treatment for anal fissure?

A

lateral subcutaneous internal sphincterotomy (DO NOT perform if 2/2 UC or Crohns)

32
Q

whats goodsall’s rule?

A

anterior fistulas connect with the anus/rectum in a straight line
posterior fistulas go toward a midline internal opening in the anus/rectum

33
Q

when can you perform wide local excision in an anal canal adenocarcinoma?

A
  1. Size <4cm
  2. <50% circumference
  3. T1 (limited to submucosa)
  4. Well differentiated
  5. No LVI/perineural invasion
34
Q

whats the difference between anal margin and anal canal cancers?

A

anal canal is above the dentate line (SCC, adenoca, melanoma)
anal margin is below the dentate line (SCC, basal cell)

35
Q

treatment of squamous cell carcinomas: anal canal vs anal margin

A
Anal canal (above dentate line) = nigro protocol
Anal margin = WLE (if <5cm, need 0.5cm margin) or Chemo-XRT (5-FU and cisplatin)
36
Q
nodal metastases:
Superior and middle rectum:
Lower rectum:
Anal Canal:
Anal Margin:
A

Superior and middle rectum: IMA nodes
Lower rectum: IMA and internal iliac nodes
Anal Canal: internal iliac nods
Anal Margin:inguinal nodes

37
Q

what is Haggitt’s classification system for malignant polyps?

A

1: invading head
2: invade neck
3: invade stalk
4: invade base, bowel wall or sessile (require segmentectomy)

38
Q

what is the most abundant bacteria in the flora of the normal colon?

A

bacteroides fragilis

39
Q

what are indications for surgical management in massive GI bleeding?

A

transfuse >6 units PRBCs, ongoing hemodynamic instability

40
Q

how to repair a parastomal hernia?

A

hernia repair with mesh! (lowest recurrence rate when fixed w mesh)

41
Q

when is elective surgery indicated in the treatment of UC?

A

refractory to medical management, severe GI bleeding, if dysplasia is found on screening colonoscopy

42
Q

what are the imaging modalities used to stage rectal cancer?

A

MRI or endoscopic US to eval depth of tumor and nodal involvement

43
Q

what is nigro protocol used for?

A

squamous cell cancers of the anal canal

44
Q

what is the neural control of the external anal sphincter?

A

voluntary control by branches of the internal pudendal and S4 nerves

45
Q

treatment of cecal volvulus?

A

surgical resection: ileocolonic anastomosis unless perforation/gangrenous bowel

46
Q

what are the criteria for candidates of transanal excision for rectal cancers? (5)

A
  1. Well differentiated T1 lesion
  2. <3cm in size
  3. < 30% circumference
  4. <8cm from anal verge
  5. No LVI or mucin production
47
Q

what are the extraintestinal conditions associated with crohns? (5) and do each improve/not improve w colectomy?

A
  1. Arthritis- improves
  2. Ankylosing spondylitis- does not improve
  3. Erythema nodosum- resolves
  4. Pyoderma gangrenosum- improve
  5. PSC- does not improve
48
Q

treatment of stage III colon cancer?

A

resection followed by FOLFOX: 5-FU, leucovorin, oxaliplatin

49
Q

what are the 5 techniques for operative repair of internal hemorrhoids?

A
  1. Miligan-Morgan: excision of hemorrhoids and leaving wound open
  2. Ferguson: excision of hemorrhoids and closing wound
  3. Whitehead: circumferential excision just above the dentate line
  4. Stapled hemorrhoidectomy
  5. Transanal hemorrhoid dearterialization
50
Q

colonocytes: secrete and absorb what electrolytes?

A

absorbs: water, sodium and chloride
secretes: potassium and bicarb

51
Q

main energy source of colonocytes?

A

short chain fatty acids

52
Q

name 3 short chain fatty acids

A

acetate, butyrate, propionate