Colon, Rectum, Anus

Question 1

Low anterior resection, which is stapled?

Answer 1

Mucosa, submucosa, longitudinal muscle, circular muscle

*mid and lower rectum lack serosa

Question 2

Which layer of muscle joins together to form the internal anal sphincter?

Answer 2

Circumferential muscle layer 📌

Question 3

Rectal fascia

Answer 3

Presacral fascia: separates the rectum from the presacral venous plxus and the pelvic nerves
WALDEYER FASCIA: rectosacral fascia; extends forward and downward and attaches to the fascia propria at the anorectal junction
DENONVILLIERS FASCIA: separates the rectum from prostate and seminal vesicles / vagina

Question 4

Physiologic intesstinal herniation

Answer 4

At the 6th week of gestation, the midgut herniates through the abdominal cavity, rotates 270degrees counter-clockwise around thhe SUPERIOR MESENTERIC ARTERY and then travels to its resting place in the abdomine during the 10th week 📌

Question 5

What happens in diversion coitis

Answer 5

Butyric acid and propionic acid are not being absorbed

Question 6

Remarks on FOBT

Answer 6

• false-positive
• red meat
• some fruits and vegetables
• vitamin C
• any positive FOBT mandates further investigation, usually by colonoscopy

Question 7

What workup is needed prior to ileostomy reversal

Answer 7

A flexible sigmoidoscopy or contrast enema to check for patency

Question 8

What is the most concerning adverse outcome in end ileostomy in the short term and will require SURGICA REVISION

Answer 8

Stoma necrosis below the level of the fascia

Question 9

Ddx for pouchitis

Answer 9

Bacterial or viral infection

Undiagnosed Crohn disease

Question 10

Remarks on IBD

Answer 10

Family history: 10-30%

Question 11

Remarks on ulcerative colitis

Answer 11

Mucosa may be atrophic, friable, with multiple peudopolyps

In long-standing UC, the colon may be FORESHORTENED and the mucosa replaced by SCAR

Question 12

What structures are mot likely to be site of extracolonic disease in IBD?

Answer 12

Liver (m/c)
Biliary tree
Joints
Skin (erythema nodosum, pyoderma gangrenosum)
Eyes (up to 10%; uveitis, iritis, episcleritis, conjunctivitis

Question 13

What is the first-line therapy for inflammatory bowel disease in the outpatient setting?

Answer 13

Salicylates, such as sulfasalazine and 5 acetyl salicylic acid (5-ASA)
MOA: inhibition of cyclooxygenase and 5-lipoxygenase in the gut mocosa

Question 14

Case of UC: What would be inications that stoma creation would be more appropriate than a primary anastomosis?

Answer 14

“A prealbumin of 6.0 in a patient who has been on corticosteroids”

*in extremely malnourished patient, especially those who are also being treated with corticosteroids, creation of a stoma is often safer than a primary anastomosis

Question 15

What are the mosmt common indications for surgery for Crohn’s disease?

Answer 15

Internal fistula or abscess (30-38%)

Obstruccctioon (35-37%)

Question 16

What would indicate that a fissure is from Crohn diseaese

Answer 16

Deep and broad ulcer located in the lateral position (rather than anterior or posterior midline as seen in an idiopathic fissure in ano)

Question 17

Remarks on diverticulitis treatment

Answer 17

• many surgeons now will not advise colectomy even after two documented episdoes of diverticiulitis, assuming the patient is completely ASYMPTOMATIC and that CARCINOMA HAS BEEN EXCLUDED by colonoscopy.
• IMMUNOSUPPRESSED PATIENTS are generally still advised to undergo COLECTOMY after a SINGLE episode of documented diverticulitis.
• all patients must be evaluated for malignancy via COLONOSCOPY 4-6 weeks after recolvery
• inability to exclude malignancy is another indication for resection

Question 18

What are the most common fistulas that develop in complicated diverticulitis?

Answer 18

Colovesical fistulas

• approx 5% of patients with complicated diverticulitis deveop fistulas bet colon and an adjacent organ
• 2nd: colovaginal, 3rd: coloenteric
• colocutaneous fistulas are rare

Question 19

What are the most common genetic mutations that could lead to colon cancer

Answer 19

APC
DCC
P53
* review K-ras, MYH 📌

Question 20

Remarks on HNPCC

Answer 20

Lynch syndrome
1-3% of all colon cancers
Mismatch repair
Cancers appear in the proximal colon more often than in sporadic colon cancer and have a better prognosis regardless of stage.
Amsterdam criteria is used

Question 21

Mutations in HNPCC

Answer 21

Mutations in PMS2 or MSH6 result in a more attenuated form of HNPCC
MHS6 inactivation also appears to be associated with higher risk for endometrial cancer

Question 22

Most common extracolonic malignancy in HNPCC

Answer 22

Endometrial cancer

Others: ovarian, pancreas, stomach

Question 23

Albumin reference value (rv)

Answer 23

35-55 g/L

3.5-5.5 g/dL

Question 24

Prealbumin rv

Answer 24

0.1-0.4 g/L
(0.01-0.04 g/dL)
(10-40 mg/dL)
*indicator of nutritinon,
*binds thyroid hormone and retinol binding protein