Gastroenterology

Question 1

Treatment options for Opioid-induced constipation

Answer 1

1) SQ methylnaltrexone
2) oral naloxegol
3) oral naldemedine

Question 2

What are the four phases of HBV infection?

Answer 2

1) Immune tolerant
2) Immune active - evidence of hepatic inflammation
3) Immune control (inactive)
4) Reactivation

Treatment is indicated in the immune active phase

Routine screening for HCC indicated (AFP, U/S)

• SE asian patients >40 y/o (male), >50 y/o (female)
• sub-saharan Africa > 20 y/o

Question 3

What are the criteria for cholecystecomy with regard to asymptomatic gallbladder polyps?

Answer 3

1) Polyp >1 cm
2) Polyp of any size in the presence of gallstones
3) Polyp >8 mm in size with coexsting PSC

Question 4

Indications for SBP prophylaxis in new ascites

Answer 4

1) Ascitic fluid protein <1.5 g/dL AND
2) Hyponatremia (<130) OR
3) Kidney dysfunction (serum Cr >1.2) OR
4) CTP Class B or C Cirrhosis

Choose fluoroquinolones for prophylaxis (norfloxacin or ciprofloxacin)

Question 5

Indications for resection of pancreatic cyst

Answer 5

1) Symptoms related to the cyst (pancreatitis, jaundice)
2) Cyst size >3 cm
3) Dilated main pancreatic duct
4) Solid component of the cyst

Surveillance: annual MRI abdomen

Question 6

Etiologies of secretory diarrhea (occurs despite fasting)

Answer 6

1) Medications - colchicine, NSAIDs
2) VIPoma, Carcinoid, Gastrinoma
3) SIBO
4) Short bowel syndrome (bile acid malabsorption)
5) Villous adenoma

Question 7

Biopsy findings in Crohn’s Disease

Answer 7

1) Distorted and branching colonic crypts
2) Neutrophilic and lymphocytic infiltration
3) Skip lesions

Question 8

What test helps diagnose SIBO?

Answer 8

Glucose hydrogen breath testing

Question 9

Positive anitmitochondrial antibodies are associated with what disease?

Answer 9

Primary Biliary Cholangitis (PBC)

~10% may test negative for antimitochondrial Abs

Think about PBC in a middle-aged woman (40-60) with a cholestatic picture +/- symptoms of jaundice, pruritis, and fatigue

Question 10

Criteria for Lynch Syndrome

Answer 10

1) Three family members affected with Lynch-syndrome associated cancers
2) Two successive generations affected
3) One affected family member is a first-degree relative of the other two affected members
4) One cancer was diagnosed <50 years
5) FAP has been ruled out

Lynch-Syndrome associated cancers:

• Colorectal
• endometrial
• Others: stomach, ovary, hepatobiliary, urinary tract, small bowel brain, pancreas, and sebaceous skin adenoma/cancer

Question 11

Where is colorectal cancer as part of Lynch Syndrome likely to occur? What are the histologic characteristics?

Answer 11

1) Proximal colon

2) Tumor-infiltrating lymphocytes, medullary growth

Question 12

Genes implicated in Lynch Syndrome

Answer 12

1) MLH1, MSH2, MSH6, PMS2 - mismatch repair genes

2) EPCAM - epithelia cell adhesion molecule

Question 13

Treatment for pyogenic vs amebic liver abscess

Answer 13

Pyogenic - usually polymicrobial, via gut translocation (most common in US). Tx is often antimicrobials plus surgery. Surgical indications:

• > 5 cm in size
• complex abscess
• presence of gas-formation
• hemodynamic instability
• biliary fistulization
• presence of foreign body

Amebic abscess - usually Entamoeba histolytica, from an endemic area (South/Central America, India, Africa). Symptom onset 3-5 months after infection, which is indicative of hepatic necrosis. Treatment:

• metronidazole
• luminal agent (paromomycin)

Question 14

Treatment of Wilson’s Disease

Answer 14

Trientine is preferred to penicillamine due to a lower rate of adverse effects.

Consider zinc supplements to decrease intestinal absorption of copper.

Question 15

GI bleed with hypotension in patient with prior aortic grafting

Answer 15

Aortoenteric fistula

• evaluate with CT + contrast
• mortality rate 50% (even with surgical intervention)

Question 16

What is alosetron used for?

Answer 16

IBD-D in women whose symptoms have not responded to conventional therapy

Risk for ischemic colitis and severe constipation
Drug monitoring program enrollment is required

Question 17

What is the Meltzer Triad? What does it indicate?

Answer 17

1) Aesthenia (weakness)
2) Arthralgias
3) Palpable purpura

Classic presentation of Type II cryoglobulinemia
Hep C a common cause, treat the virus

Question 18

How do you calculate the stool osmolar gap?

Answer 18

290 - 2[stool Na + stool K]

> 100 is consistent with osmotic
< 50 is consistent with secretory (think high stool Na and high stool K)

Question 19

Fever, diarrhea, weight loss in an AIDS patient: etiologies

Answer 19

1) Cryptosporidium
2) E. histolytica
3) Giardia
4) isospora
5) Strongyloides
6) AIDS enteropathy

Question 20

Rarer causes of chronic diarrhea

Answer 20

1) Diabetes
2) Amyloidosis - visceral autonomic neuropathy, gastroparesis, postural hypotension
3) Carcinoid syndrome
4) Lactase deficiency
5) IBS-D

Question 21

How to diagnose Carcinoid Syndrome

Answer 21

1) 24hr urine 5-HIAA (positive if >25 mg/day)
2) CT may show metastases in liver
3) MRI and octreoscan (many carcinoid tumors express somatostatin receptors, which are bound by the radiolabeled somatostatin analogue octerotide)

A 24 hour fast will improve osmolar diarrhea, but not secretory diarrhea

Question 22

Malabsorption (chronic diarrhea) can cause which 6 major deficiencies?

Answer 22

Think “PIC ACC”

P: PT/INR - Vitamin K deficiency
I: Iron deficiency
C: Calcium deficiency
A: Albumin
C: Cholesterol
C: Carotene (Vitamin A) deficiency

Question 23

Which ARB has been associated with enteropathy/malabsorption?

Answer 23

Olmesartan: causes sprue-like enteropathy

Question 24

Whipple’s Triad:

Answer 24

1) Arthraligas
2) Abdominal pain
3) Diarrhea/malabsorption leading to weight loss

Caused by gram + bacillus T. whipplei
Can see Neuro sx (depression, paranoia, dementia)
Biopsy: Foamy macrophages, +PAS staining
Tx: Ceftriaxone or PCN IV x14 days, then TMP/SMX x1 year

Question 25

Medications for IBS-C

Answer 25

1) Linaclotide
2) Lubiprostone

Both stimulate intestinal secretion

Question 26

What are the inherited polyposis syndromes

Answer 26

1) FAP: AD, APC gene, 100s to 1000s of adenomas, 100% CA risk, proctocolectomy needed, screen for duodenal CA
2) Attenuated FAP: AD, APC gene, 10s-100s of polyps, delayed-onset CRC
3) MUTYH polyposis - AR, phenotype is similar to attenuated FAP, screen for duodenal CA as well
4) Gardner Syndrome: Variant of FAP with tumors outside of the colon (osteomas, thyroid cancer, desmoids)
5) Peutz-Jeghers syndrome: harmartomatous polyps, small bowel, stomach and colon. Freckles on lips/buccal mucosa, intussusception is common, increased CA risk (CRC, stomach, breast, pancreatic)
6) Juvenile Polyposis: consider if 3-5 juvenile polyps of the colon

7) Serrated Polyposis Syndrome
- Five or more serrated polyps proximal to the sigmoid colon, with two or more greater than 10 mm in size
- Any number of serrated polyps in patients with first-degree relatives with serrated polyposis syndrome
- More than 20 serrated polyps throughout the colon

Question 27

Non-polyposis Colorectal Syndromes

Answer 27

1) Lynch

2) PTEN Hamartoma (Cowden Syndrome)

Question 28

Colonoscopy follow up interval for one or two tubular adenomas (<1 cm)?

Answer 28

5 years

Question 29

Colonoscopy follow up interval for 3-10 adenomas?

Answer 29

3 years

Question 30

Colonoscopy follow up interval for an adenoma >1 cm?

Answer 30

3 years

Question 31

Colonoscopy follow up interval for small rectal hyperplastic polyps?

Answer 31

10 years

Question 32

Colonoscopy follow up interval for adenoma with high-grade dysplasia or villous features?

Answer 32

3 years

Question 33

Colonoscopy follow up interval for >10 adenomas?

Answer 33

<3 years, consider familial polyposis syndrome

Question 34

Colonoscopy follow up interval for large (>2 cm) sessile polyp removed in piecemeal fashion?

Answer 34

2-6 months

Question 35

Colonoscopy follow up interval for polyp with adenocarcinoma (minimal invasion, >2 mm margin)?

Answer 35

2-3 months

Question 36

Treatment for HBV

Answer 36

Tenofovir
Entecavir
Pegylated interferon