Colorectal

Question 1

Colon secretes______ and absorbs____

Answer 1

Potassium and reabsorbs sodium and water

Question 2

Layers of colon

Answer 2

Mucosa
submucosa
muscularis propria
serosa

Question 3

Which parts of colon are retroperitoneal

Answer 3

Ascending, descending and sigmoid

Anterior upper and middle 1/3rd of rectum

Question 4

vascular supply
Ascending:
Transverse
Descending
Sigmoid
Rectum

Answer 4

Ascending: SMA(Ileocolic and Right colic)
Transverse (proximal 2/3 by SMA. Distal 1/3 by IMA. Middle colic)
Descending: IMA Left colic
Sigmoid IMA: Sigmoid
Rectum Upper: IMA Superior rectal
Lower: internal Iliac: Middle rectal; internal Iliac to internal pudendal to inferior rectal.
Marignal artery of drummond: Connects SMA to IMA

Question 5

Venous supply of colon

Answer 5

Follows arterial. SMV joins IMV to form portal vein behind pancreas
Rectum: Inferior rectal vein to internal iliac veins.
Superior and middle drain to IMV to portal.
Lymph nodes are similar

Question 6

Watershed areas

Answer 6

Griffiths point: Splenic flexure at SMA and IMA junction and
Sudaks Point at rectum at superior and middle rectal junction

Question 7

External sphincter: Which muscle. Controlled by?

Answer 7

Puborectalis, extension of levator Ani, controlled by CNS: Inferior rectal branch of internal pudendal nerve

Question 8

Internal Sphincter: which muscles and Control

Answer 8

Extension of muscularis propria

Involuntary bypelvic splanchnic nerves

Question 9

Meissner and auerbach

Answer 9

INNER plexus

Auerbach: Outer

Question 10

distance from anal verge:
Anal canal
Rectum
Rectosigmoid junction

Answer 10

5cm
5-15
15-18

Question 11

main nutrient of colonocytes

Answer 11

Short chain fatty acids

Question 12

tx of stump pouchitis

Answer 12

Short chain fatty acid enema

Question 13

Tx of infectious pouchitis

Answer 13

Flagyl

Question 14

Denonvilliers fascia and waldeyers fascia

Answer 14

Rectovesicular and rectoprostatic (denon)

waldeyers: Retrosacral fascia

Question 15

most common polyp

Answer 15

Hyperplastic

Question 16

Most common neoplastic

Answer 16

Tubular adenoma most are pedunculated

Question 17

Most likely polyp to cause symptoms

Answer 17

Villous adenoma. Likely sessile

Question 18

Polyp characteristics likely to cause ca:

Answer 18

> 2cm, sessile, villous

Question 19

polypectomy vs segmental resection. When is polypectomy sufficient

Answer 19

If margin >2mm, not poorly differentiated and no evidence of lymphovascular involvement.

Question 20

high grade dysplasia vs intramucosal vs invasive ca

Answer 20

in first two, basement membrane remains intact, in invasive ca, submucosa involved

Question 21

false positive guaic fobt causes

Answer 21

beef, vitamin c, iron, cimetidine

Question 22

contraindications to colonoscopy

Answer 22

recent MI, splenomegaly, pregnancy(if fluoro)

Question 23

tx of extensive low rectal villous adenomas with atypia

Answer 23

trans anal excision ( NO APR unless cancer

Question 24

transanal exsion shows T1 cancer. Further tx needed?

Answer 24

No. If margins are adequate(2mm), no lymphovascular invasion and well differentiated.

Question 25

Transanal excision shows T2: further Tx needed?

Answer 25

APR or LAR needed.

Question 26

symptoms of colorectal ca;

Answer 26

anemia, bleeding constipation

Question 27

colon ca a/w which infxn?

Answer 27

clostridium septicum.

Question 28

main mutations in colon ca

Answer 28

p53, DCC, KRAS, APC

Question 29

Most common site

Answer 29

Sigmoid

Question 30

Mets to

Answer 30

liver(via portal vein) and lung(via iliac vein)

Question 31

5 year survival in liver mets?

Answer 31

35% if resectable with adequate liver fxn

Question 32

5 YS in lung mets

Answer 32

25% after resection

Question 33

rectal ca mets to spine via?

Answer 33

Batsons plexus(venous)

Question 34

prognosis with lymphocytic penetration? Mucoepidermoid ca?

Answer 34

LC: improved prognosis ME: Worse

Question 35

TRUS

Answer 35

BEST test of assesing T and N status

Question 36

Goals of resection

Answer 36

EN bloc resection with adequate margins, mesocolon, regional adenectomy 2cm margins

Question 37

best way to pick intrahepatic mets

Answer 37

intraop u/s. 3-5mm resolution vs conventionu/s 10mm vs ct/mri (5-10)

Question 38

APR Indications

Answer 38

Malignant lesions only, not amenable to LAR. | Lesions with <2cm margin from levator ani

Question 39

Criteria for transanal excision of low rectal T1 lesions

Answer 39

<4cm. Negative margins, well differentiated, no lymhovascular involvement. T2 or higher: APR/LAR

Question 40

Chemo. colon: Stage III and IV rectal stage II and III rectal IV

Answer 40

colon: Stage III and IV: postop rectal stage II and III neoadjuvant rectal IV chemo +radio possibly surgery chemo regimen: 5FU leucovorin, oxaliplatin

Question 41

XRT. damage, advantage

Answer 41

Can cause vasculitis, thrombosis, ulcers, strictures, bleeding can allow downstaging, helping avoid morbid operations

Question 42

``` FAP gene? when do polyps form age of prophylactic colectomy other common cancer surgery ```

Answer 42

AD APC gene, chromosome 5 20y. prophylactic colectomy, rectal mucosectomy, ileoanal pouch periampullary duodenal tumors.

Question 43

Other APC gene associated tumors:

Answer 43

Gardners: FAP and desmoid tumors/osteomas turcot: Colon ca and brain ca

Question 44

``` Lynch syndrome Gene Lynch 1 vs 2 Amsterdam criteria when to start screening. ```

Answer 44

AD DNA mismatch repair genes. 1: just colon ca. 2: increase risk of ovarian, endometrial, bladder and stomach. Amsterdam: 3-2-1. 3 first degree relatives, 2 generations, 1 cancer before 50. screen at 25 or 10 years before total proctocolectomy

Question 45

cecal vs sigmoid volvulu

Answer 45

age. cecal in young, 20-30s, sig in old, psych patients, neuro dysfxn, laxative abuse,