Colon (Makary Ch 22)

Question 1

What disease/syndrome associated with a mutation in the APC gene?

Answer 1

Familial Adenomatous Polyposis

Question 2

When should patients with FAP begin screening?

Answer 2

Flex sig starting at age 10-15

Question 3

Should you palliate a low rectal obstructing tumor with an endoluminal stent?

Answer 3

No - cause pain and incontinence at this site. A sigmoid colostomy is a better option.

Question 4

Do loop colostomies or loop ileostomies have more complications?

Answer 4

Loop colostomies - higher incidence of parastomal and incisional hernias, stomal prolapse, and fecal fistulas

Question 5

The colon secretes ___ and reabsorbs ___ and water (electrolytes)

Answer 5

Secretes K, reabsorbs Na

Question 6

Four layers of the colon

Answer 6

mucosa, submucosa, muscularis propria, serosa

Question 7

Name of the transverse bands that form haustra

Answer 7

Plicae semilunares

Question 8

Ascending and 2/3 of transverse colon supplies by the

Answer 8

SMA (ileocolic, right, middle colic)

Question 9

1/3 transverse, descending colon, sigmoid colon, and upper portion of rectum supplied by the

Answer 9

IMA (left colic, sigmoid branches, superior rectal artery)

Question 10

What artery runs along the colon margin, connecting the SMA and IMA

Answer 10

Marginal artery - provides collateral flow

Question 11

What two layers of the colon receive 80% of the blood flow?

Answer 11

the mucosa and submucosa

Question 12

The middle rectal artery is a branch of the

Answer 12

internal iliac artery

Question 13

The inferior rectal artery is a branch of the

Answer 13

internal pudendal artery, which is a branch of the internal iliac

Question 14

What are the two watershed areas?

Answer 14

splenic flexure - SMA and IMA junction

Rectum - superior rectal and middle rectal junction

Question 15

Colon vs Small bowel - which is more sensitive to ischemia?

Answer 15

Colon - less collateral blood flow

Question 16

What is the main nutrient of colonocytes?

Answer 16

Short chain fatty acids

Question 17

What is the most common polyp? Cancer risk?

Answer 17

Hyperplastic polyps - no cancer risk

Question 18

What is the most common intestinal neoplastic polyp?

Answer 18

Tubular adenoma

Question 19

Does high grade dysplasia violate the basement membrane?

Answer 19

No. The basement membrane is in tact (carcinoma in situ)

Question 20

To be considered invasive, the cancer must violate which layer?

Answer 20

The submucosa

Question 21

Screening option:

• Colonoscopy q___ years
• FOBT Q___ years + Flex sigmoidoscopy Q ___ years
• FOBT only q ___ years

Answer 21

• Colonoscopy q10 years
• FOBT Q3 years + Flex sigmoidoscopy Q 5 years
• FOBT only q 1 year

Question 22

Four things that can cause a false positive guaiac test

Answer 22

Beef, vitamin C, iron, cimetidine

Question 23

for a polypectomy to be adequate, need ___ mm margin

Answer 23

2mm

Also should be well differentiated, have no vascular/lymphatic invasion

Question 24

What is the treatment for extensive low rectal villous adenomas with atypia

Answer 24

Transanal excision. No APR unless cancer is present

Question 25

Pathology shows T1 lesion after transanal excision of villous rectal polyp with 2mm margins. Adequate?

Answer 25

yes - if also well differentiated and no vascular/lymphatic invasion

Question 26

Pathology shows T2 lesion after transanal excision of villous rectal polyp. Adequate?

Answer 26

No. Patient needs APR or LAR