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NP 730 Diagnostic Measures > Gastroenterology > Flashcards

Gastroenterology Flashcards

1
Q

H. pylori transmission

RFs that increases risk of transmission

A
  • Fecal-oral
  • Gastric cancer increases risk of transmission
    • Smoking, obesity RFs; no specific recommendations for screenings
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2
Q

H. pylori testing types (2)

A
  • Invasive - Endoscopic - taking biopsies of gastric mucosa
    • Biopsy urease testing
    • Histology
    • Bacterial C&S
  • Non-invasive
    • Stool antigen
    • Urea breath testing (UBT)
    • Serology
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3
Q

Test & Treat H. pylori criteria

PIMND

A
  • Only if < 55 and no alarm symptoms!! Do non-invasive test
  • Active or hx of PUD
  • Dyspepsia - indigestion
  • Gastric MALT lymphoma - cancer
  • NSAID induced ulcers
  • Unexplained iron deficiency anemia (if can’t find source of blood loss)
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4
Q

Endoscopy criteria for H. pylori

Alarm symptoms: FAJAW GORD

A
  • > 55 regardless of what the symptoms are or alarm s/s
  • Alarm symptoms
    • Unexplained weight loss
    • Progressive dysphagia
    • Odynophagia
    • Recurrent vomiting
    • Family hx of GI cancer
    • GI bleeding
    • Anemia
    • Jaundice
    • Abd mass
  • Endoscopy not indicated for sole purpose of determining H. pylori status
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5
Q

Endoscopic approach testing for H. pylori

Biopsy urease testing

A
  • Biopsy urease - look for presence of irease in gastric mucosa (urea and pH)
    • High S + S
    • Less $$ than histology
    • Can only be used if no recent PPI, bismuth or abx use
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6
Q

Endoscopic approach for H. Pylori testing

Histology

A
  • Histology - a little more accurate than urease testing
    • High S + S
    • Can be done if patient has recently been on PPI, bismuth, or abx - sensitivity may be decreased
    • More $$$
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7
Q

Endoscopic approach testing for H. pylori

Bacterial C&S

A
  • Bacterial C&S - not very common
    • Performed on gastric biopsies of patients with resistance infection/treatment failure
    • High false negative rate - H. pylori is difficult to culture
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8
Q

Non-invasive H. Pylori Testing

Urea breath testing (UBT)

A
  • Ingestion of non/radioactiveurea labeled → H. Pylori cleave urea → ammonia + CO2 which is marked w/isotope + detectable in breath samples
    • Highly S + S (most of the three here)
    • Cannot be used if any PPI, bismuth or abx use in the last 2 weeks
    • False negatives may be seen with bleeding ulcers–Expensive
  • More accurate in children > 6
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9
Q

Non-invasive H. Pylori Testing

Stool antigen assay

A
  • Need to return the stool sample before starting medication
    • Less $$ than UBT + slightly less affected by PPI use
    • Still recommend avoidance of PPIs, bismuth or abx for 2 weeks
    • POC test not as sensitive but lab based testing equal to UBT
    • Can be used for diagnosis and confirmation of eradication
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10
Q

Non-invasive H. Pylori Testing

Serology

A
  • Blood test
  • ELISA test to detect H. Pylori IgG antibodies
  • Inexpensive
  • Not accurate (85% sensitive and 79% specific) risk for false positive and false negative
  • Does not determine between active and past infection
  • Not affected by PPI, bismuth, antibiotic use
  • Not generally recommended
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11
Q

Test & Treat recommended in children H. pylori?

A

NO

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12
Q

H.pylori testing recommended for children or children w/functional abd pain?

A

NOT RECOMMENDED

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13
Q

When would you do an endoscopy w/biopsy for children with possible H. pylori infection?

A

If infection is persistent or they’re experiencing severe upper abd discomfort

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14
Q

When should you confirm eradication of H. pylori after antibiotic?

Which tests should you do? Which one should you not use?

A

Should be performed at least 4 weeks after completion of abx tx

Can use either UBT, stool Ag test, or endoscopy based testing

NOT SEROLOGIC TESTING

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15
Q

Endoscopy procedure

Prep, during, after, risk factors

A
  • Involves visualization of oropharynx, esophagus, stomach, and proximal duodenum
  • Typically NPO for 4-8 hours prior to procedure
  • Generally no need to stop aspirin or NSAIDs, other anticoagulants require a risk/benefit assessment
  • Sedation typically accomplished with IV benzodiazepines +/- opiates
  • Patient’s will require a ride home from the procedure
  • Increased risk for complications relating to sedation in patients with:
    • OSA – sleep apnea (aspiration)
    • Significant cardiac or pulmonary disease
    • Those with increased aspiration risk: morbid obesity, bowel obstruction, dysphagia, reflux
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16
Q

Upper endoscopy

GI series

Barium swallow

Slide 12: perform? Visualize? When to order?

A
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17
Q

When do you start screening patients for colon cancer if they have no risk factors?

A

At 50 years old

May decrease to age 45 d/t increased prevalence of colon cancer at younger age

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18
Q

Gold standard screening test for colon cancer

A

COLONOSCOPY

B/c have good visualization of colon and can take biopsy during procedure if abnormal

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19
Q

When do you repeat testing for colonoscopy if result is normal?

A

10 years unless symptomatic

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20
Q

Two types of colon polyps

Which one is cancerous?

A
  • Adenomatous: precancerous → screening repeat colonoscopy sooner than 10 yrs
  • Hyperplastic: not cancerous → no need for repeat testing, just in 10 yrs (usually GI specialist will determine)
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21
Q

Colon cancer screening method:

Fecal Occult Blood Test (FOBT)

A
  • Guiac
  • Qyearly for CRC screening - Noninvasive
  • Rapid, inexpensive but POOR SPECIFICITY (high false positives)
    • Can do testing at home
    • Hemorrhoids can give false positives
  • Dietary restrictions: avoid red meat (can interfere) 3d prior and NSAIDs 7d prior
  • Requires 3 samples
  • POSITIVE → COLONOSCOPY to find source of bleeding
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22
Q

Colon cancer screening method:

Fecal Immunochemical Test (FIT)

A
  • Qyearly - Noninvasive
  • Uses abx directed against human Hgb to detect blood in stool
  • Less sensitive to dietary changes than FOBT
  • Requires only 1 sample vs. 3 for FOBT
  • PREFERRED OVER FOBT TESTING - more accurate
  • No diet prep or changes in meds
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23
Q

Colon cancer screening method:

CT colonography

A
  • Q5yrs - Noninvasive
  • Ordered by a specialist, not commonly ordered in primary setting
  • 2D → 3D views of colon and rectum
  • Come back positive (dx only) → COLONOSCOPY
  • Fasting + laxative
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24
Q

Colon cancer screening method:

Flexible sigmoidoscopy

A
  • Q3-5yrs - INVASIVE
  • Not as common in primary care setting
  • Examine’s entire rectum, and half of colon
  • Need sedation - air put in
  • Can do biopsies
  • Fasting + laxative
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25
Q

Colon cancer screening method:

Colonoscopy

A
  • Q10yrs - INVASIVE
  • Rectum → entire colon
  • Can get biopsies
  • Fasting + laxative - drink clear liquid to empty colon
  • Sedation
  • GOLD STANDARD
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26
Q

Colon cancer screening method:

Stool DNA (Cologuard)

A
  • Q3yrs for screening
  • No special diet or prep
  • Single stool specimen - says positive or negative
    • Checks for blood in stool and colon cancer DNA
  • Insurance coverage varies
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27
Q

Categories for chronic diarrhea

What lab do you also check?*

A
  • Watery (osmotic, secretory, functional)
  • Fatty (malaborption)
  • Inflammatory (blood, purulence)

thyroid!!!

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28
Q

Chronic diarrhea differentials

A
  • IBS
  • IBD (UC, Crohn’s)
  • Lactase deficiency
  • Celiac disease
29
Q

Chronic Diarrhea red flags

A
  • New persistent changes in bowel habits/meds
  • FMHx colorectal cancer, IBD, CD, age of screening younger
  • Anemia
  • Weight loss
  • Fever
  • Early satiety
30
Q

Rome IV Criteria - for IBS

A
  • Recurrent abd pain, on average, @ least 1d/wk in the last 3mos , associated w/2 or more of the following criteria
    • Defecation - pt feel better post BM
    • Change in stool frequency
    • Change in stool form: liquid, harder, fatty, etc
31
Q

Manning Criteria - for IBS

A
  • Onset of pain linked to more frequent BMs
  • Looser stools w/onset of p!
  • P! relieved by passage of stool
  • Abd bloating
  • Incomplete evacuation of bowels sensation > 25% of time
  • Diarrhea W/MUCUS > 25% of time
32
Q

IBS diagnosis workup (4 steps)

A
  1. Consistent hx: food + s/s diary
    1. Fiberous foods, high fat content foods
  2. Absence of alarm features (s/s)
  3. Limited work-up to exclude other disease, CD + IDA
  4. Trial of fiber, exercise, dietary modification
  5. Stress induced
33
Q

IBS lab work-up

A
  • CBC + TSH (anemia + thyroid disease differential)
  • Diarrhea → CRP or fecal calprotectin (inflammation), celiac serology, BMP, Giardia
    • CRP - inflammation - ⇡ in IBD
    • Fecal calprotectin - ⇡ in IBD
    • BMP for chronic diarrhea - dehydration + Es
34
Q

Fecal calprotectin

A
  • Lab distinguishing IBS vs. IBD
  • Non-invasive; stool collection kit
    • 51-120 = borderline high → repeat in 4wks
    • 120+ abnormal → IBD suspected → colonoscopy
  • Less accurate in kids; high S + S
35
Q

Celiac disease

What?

A
  • Autoimmune disease - triggered by gluten exposure → attacking GI → inflammation + malabsorption
  • Can develop at any age
  • W > M
  • Both intestinal and extraintestinal manifestations
36
Q

Celiac disease Intestinal manifestations

A
  • Lactose intolerance
  • Malabsorption syndrome
  • Nutritional deficiencies
37
Q

Celiac disease Extra intestinal manifestations

A
  • Anemia - d/t malabsorption
  • Dermatitis herpetiformis - autoimmune rash
  • Hepatobiliary s/s
  • Neuro abnormalities
  • Osteoporosis
  • Hematologic abnormalities
  • Reproductive abnormalities
38
Q

Gold standard for celiac testing

A

DUODENAL BIOPSY

Generally check serology first due to invasiveness of biopsy

39
Q

Celiac testing - Serology types

Schematic picture

A
  • Gliadin - not a great test w/this: poor S+S
  • tTG - preferred
  • EMA - more sensitive but $$
40
Q

Celiac Antibodies

A
  • AgA: anti-gladin antibodies
    • No longer generally used
  • IgA EMA: endomysial antibodies
    • $$$$; mostly specific than sensitive
  • IgA tTG: tissue translutaminase - preferred
41
Q

(-) IgA tTG + normal IgA

Result?

A

NOT CD

42
Q

(-) IgA tTG + ⇣ IgA

Result?

A

NOT ACCURATE

43
Q

(+) IgA tTG + normal IgA

Result?

A

YES CD!!

If the IgA is normal → can trust the test result

44
Q

False (-) CD serology when…

A

Deficient in IgA - SIgAD: selective immunoglobulin A deficiency

M > F genetic immunodeficiency

45
Q

If patient is already on gluten free diet, what will the antibody test result be?

A

NEGATIVE

46
Q

HLA genotyping

A

Test of choice: rule out disease if HLA is negative

Especially If person has been on gluten free diet for a while

47
Q

If patient has been on gluten diet for a long time, how does that affect the result of HLA test?

A

Doesn’t effect it -> only effects IgA

Consider reintroducing gluten diet for 2-4 weeks then test

48
Q

Celiac disease lab workup

Screening maintenance

A
  • CBC
  • Ferritin
  • Iron
  • LFTs
  • Vit B12
  • Vit D
  • Copper
  • Zinc
  • Calcium

Annually: These labs and tTG for adherence to GF diet

Bone density

EGD: if symptomatic; or to reassess disease within few years

49
Q

Acute diarrhea

Criteria for acute; common etiologies

A
  • < 14d
  • Most common: viral
  • Second most common: bacterial
50
Q

Acute diarrhea differentials

A
  • Viral, Bacterial, Parasitic
  • Non-infectious process
    • Meds: Mg, metformin, abx, PPIs, NSAIDs
    • Diet: lactulose, wheat, fiber
    • IBS/IBD
    • EtOH
    • Stress
51
Q

Inflammatory vs. non-inflammatory causing

A

Non-inflammatory most common

52
Q

Acute diarrhea diagnostic testing criteria

A
  • Usually self-limiting
  • Fever
  • Bloody stool
  • Severe abd pain
  • Immunosuppressed
  • Recent abx tx
  • Recent hospitalization
  • Moderate/severe symptoms for over a week
  • Age > 70
  • Rehydration most important intervention
53
Q

Stool testing modalities

A
  • Fecal Occult Blood Testing
  • Leukocyte & Lactoferrin Testing
  • Stool Culture
  • Ova & Parasite Testing
  • Clostridium Difficile Testing
54
Q

Clues to bacterial etiology causing stool issues

A
  • Associated with travel, food borne illness (raw food, everyone else you shared food with is sick)
  • Often bloody diarrhea

Shiga-toxin producing e. coli (do not give abx to!!)

Salmonella, campylobacter, shigella

55
Q

Leukocyte and lactoferrin testing

A
  • Assess for signs of bacterial infection/inflammation
  • Leukocyte - less common d/t wide variability in S + S
  • Lactoferrin - protein expressed by activated neutrophils, marker for bacterial infection or IBD
    • Immunoassay kits available
    • More sensitive than specific
56
Q

Stool culture

Inpatient setting indications

A
  • Routine culture detects salmonella, campylobacter, shigella
  • Inefficient and expensive
  • Recommended w/gross blood in stool or if diarrhea lasting > 10-14d
    • Severe cases of dehydration
    • s/s if Inflamm disease
    • Prolonged s/s
    • Immunosuppression
  • Inpatient setting - use if onset > 3d post hospital admission
    • RFs: Nosocomial outbreak, HIV, neutropenia, > 65 w/comorbidity
57
Q

Salmonella gold standard testing

Do most pts w/this require treatment?

A

Stool culture

Require no treatment - tx symptomatically

Treat: severe disease, immunocompromised, Type A typhoid fever

58
Q

Campylobacter

A
  • Can look similar to salmonella and tx similar to salmonella
  • Stool culture gold standard
  • Fecal-oral
  • From undercooked chicken
59
Q

Shigella

A
  • Often inflammatory
  • Frequent diarrhea, tenesmus
  • Fecal-oral transmission - water/food
  • Stool culture gold standard
60
Q

E. coli

A
  • Fecal-oral
  • Diarrhea, abd cramping, sometimes bloody diarrhea
  • Beware of abx use!!
61
Q

Shiga-toxin producing E. coli

A
  • Severe stomach cramps, bloody diarrhea, vomiting, afebrile/minimal fever
  • Risk for developing Hemolytic Uremic Syndrome - longer pt exposed to this bacteria
    • Microangiopathic hemolytic anemia
    • Thrombocytopenia
    • Acute renal failure
  • Antibiotic tx should be avoided
    • Do not use until STEC ruled out
    • No evidence abx beneficial tx
    • HYDRATION IS TX, SUPPORTIVE
62
Q

Indications for Ova & Parasite testing

A
  • > 7d + associated with
    • Infant in daycare (giardia)
    • Waterborne outbreaks (giardia)
    • Travel to developing countries
    • Immunocompromised (I.e. HIV)
63
Q

Giardia infection

A
  • Usually non-inflamm
  • (-) fever
  • Fecal-oral transmission via contaminated water
  • gold standard test: stool ova & parasite testing
64
Q

Traveler’s diarrhea workup

A
  • Uncomplicated cases do not require any workup and only supportive/symptomatic tx → typically resolve w/in 5d
  • Do not give abx
65
Q

C. difficile

A
  • Always liquid stool, NOT FORMED
  • Seen in long-term care, hospitals, community acquired
  • Toxigenic vs non-toxigenic
  • Asymptomatic carriers = NO TREATMENT, unless > 3 stools in 24hrs + RFs
66
Q

C. Difficile testing options

Lab approach to dx of C. diff (picture slide 38)

A
  • Culture - not effective; Cannot distinguish toxin vs non-toxin
  • Cell culture cytotoxicity assay
    • Measures antitoxin effect - not effective
  • *Toxin Immunoassay (ELISA)
    • Fast, easy to perform, inexpensive
    • Lots of false (-)
  • *GDH Ag immuno assay (ELISA)
    • Fast, easy to perform, inexpensive
    • Cannot distinguish toxin vs non-toxin
  • Polymerase Chain reaction (PCR) (NAAT)*
    • Fast, very sensitive, very specific for toxigenic strains
    • $$$$
    • Doesn’t measure active toxin production → False (+) in subclinical cases, asymptomatic carriers
67
Q

Indications for abdominal x-ray

What to check-off when looking

A
  • Ruling in/out bowel perforation or obstruction
  • Constipation workup - but not useful
  • MAYBE RENAL STONES → U/S or CT
  • Look at small vs large bowel
  • Black = gas/air
  • If concerned about perforation/SBO make sure you get upright view → air rises!
68
Q

Abd x-ray free air interpretation

A
  • Perforation!!!
    • Caused by trauma, infection, ruptured ulcer, obstruction, foreign body
    • Visible under diaphragm when upright
69
Q

Abd x-ray obstruction interpretation

A
  • Assess bowel gas pattern
  • Dilated loops of small bowel (>3cm)
    • Can be seen upright or supine
  • Differential air/fluid levels
    • More than 2 air fluid levels that differ in height
    • > 2cm difference – concern for SBO„
    • Seen on upright film

NP 730 Diagnostic Measures (11 decks)

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