Gastroenterology Flashcards
H. pylori transmission
RFs that increases risk of transmission
- Fecal-oral
- Gastric cancer increases risk of transmission
- Smoking, obesity RFs; no specific recommendations for screenings
H. pylori testing types (2)
- Invasive - Endoscopic - taking biopsies of gastric mucosa
- Biopsy urease testing
- Histology
- Bacterial C&S
- Non-invasive
- Stool antigen
- Urea breath testing (UBT)
- Serology
Test & Treat H. pylori criteria
PIMND
- 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)
Endoscopy criteria for H. pylori
Alarm symptoms: FAJAW GORD
- > 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
Endoscopic approach testing for H. pylori
Biopsy urease testing
- Biopsy urease - look for presence of irease in gastric mucosa (urea and pH)
- High S + S
- Less $$ than histology
- Can only be used if no recent PPI, bismuth or abx use
Endoscopic approach for H. Pylori testing
Histology
- Histology - a little more accurate than urease testing
- High S + S
- Can be done if patient has recently been on PPI, bismuth, or abx - sensitivity may be decreased
- More $$$
Endoscopic approach testing for H. pylori
Bacterial C&S
- 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
Non-invasive H. Pylori Testing
Urea breath testing (UBT)
- 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
Non-invasive H. Pylori Testing
Stool antigen assay
- 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
Non-invasive H. Pylori Testing
Serology
- 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
Test & Treat recommended in children H. pylori?
NO
H.pylori testing recommended for children or children w/functional abd pain?
NOT RECOMMENDED
When would you do an endoscopy w/biopsy for children with possible H. pylori infection?
If infection is persistent or they’re experiencing severe upper abd discomfort
When should you confirm eradication of H. pylori after antibiotic?
Which tests should you do? Which one should you not use?
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
Endoscopy procedure
Prep, during, after, risk factors
- 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
Upper endoscopy
GI series
Barium swallow
Slide 12: perform? Visualize? When to order?
When do you start screening patients for colon cancer if they have no risk factors?
At 50 years old
May decrease to age 45 d/t increased prevalence of colon cancer at younger age
Gold standard screening test for colon cancer
COLONOSCOPY
B/c have good visualization of colon and can take biopsy during procedure if abnormal
When do you repeat testing for colonoscopy if result is normal?
10 years unless symptomatic
Two types of colon polyps
Which one is cancerous?
- 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)
Colon cancer screening method:
Fecal Occult Blood Test (FOBT)
- 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
Colon cancer screening method:
Fecal Immunochemical Test (FIT)
- 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
Colon cancer screening method:
CT colonography
- 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
Colon cancer screening method:
Flexible sigmoidoscopy
- 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
Colon cancer screening method:
Colonoscopy
- Q10yrs - INVASIVE
- Rectum → entire colon
- Can get biopsies
- Fasting + laxative - drink clear liquid to empty colon
- Sedation
- GOLD STANDARD
Colon cancer screening method:
Stool DNA (Cologuard)
- 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
Categories for chronic diarrhea
What lab do you also check?*
- Watery (osmotic, secretory, functional)
- Fatty (malaborption)
- Inflammatory (blood, purulence)
thyroid!!!
Chronic diarrhea differentials
- IBS
- IBD (UC, Crohn’s)
- Lactase deficiency
- Celiac disease
Chronic Diarrhea red flags
- New persistent changes in bowel habits/meds
- FMHx colorectal cancer, IBD, CD, age of screening younger
- Anemia
- Weight loss
- Fever
- Early satiety
Rome IV Criteria - for IBS
-
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
Manning Criteria - for IBS
- 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
IBS diagnosis workup (4 steps)
- Consistent hx: food + s/s diary
- Fiberous foods, high fat content foods
- Absence of alarm features (s/s)
- Limited work-up to exclude other disease, CD + IDA
- Trial of fiber, exercise, dietary modification
- Stress induced
IBS lab work-up
- 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
Fecal calprotectin
- 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
Celiac disease
What?
- Autoimmune disease - triggered by gluten exposure → attacking GI → inflammation + malabsorption
- Can develop at any age
- W > M
- Both intestinal and extraintestinal manifestations
Celiac disease Intestinal manifestations
- Lactose intolerance
- Malabsorption syndrome
- Nutritional deficiencies
Celiac disease Extra intestinal manifestations
- Anemia - d/t malabsorption
- Dermatitis herpetiformis - autoimmune rash
- Hepatobiliary s/s
- Neuro abnormalities
- Osteoporosis
- Hematologic abnormalities
- Reproductive abnormalities
Gold standard for celiac testing
DUODENAL BIOPSY
Generally check serology first due to invasiveness of biopsy
Celiac testing - Serology types
Schematic picture
- Gliadin - not a great test w/this: poor S+S
- tTG - preferred
- EMA - more sensitive but $$
Celiac Antibodies
- AgA: anti-gladin antibodies
- No longer generally used
- IgA EMA: endomysial antibodies
- $$$$; mostly specific than sensitive
- IgA tTG: tissue translutaminase - preferred
(-) IgA tTG + normal IgA
Result?
NOT CD
(-) IgA tTG + ⇣ IgA
Result?
NOT ACCURATE
(+) IgA tTG + normal IgA
Result?
YES CD!!
If the IgA is normal → can trust the test result
False (-) CD serology when…
Deficient in IgA - SIgAD: selective immunoglobulin A deficiency
M > F genetic immunodeficiency
If patient is already on gluten free diet, what will the antibody test result be?
NEGATIVE
HLA genotyping
Test of choice: rule out disease if HLA is negative
Especially If person has been on gluten free diet for a while
If patient has been on gluten diet for a long time, how does that affect the result of HLA test?
Doesn’t effect it -> only effects IgA
Consider reintroducing gluten diet for 2-4 weeks then test
Celiac disease lab workup
Screening maintenance
- 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
Acute diarrhea
Criteria for acute; common etiologies
- < 14d
- Most common: viral
- Second most common: bacterial
Acute diarrhea differentials
- Viral, Bacterial, Parasitic
- Non-infectious process
- Meds: Mg, metformin, abx, PPIs, NSAIDs
- Diet: lactulose, wheat, fiber
- IBS/IBD
- EtOH
- Stress
Inflammatory vs. non-inflammatory causing
Non-inflammatory most common
Acute diarrhea diagnostic testing criteria
- 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
Stool testing modalities
- Fecal Occult Blood Testing
- Leukocyte & Lactoferrin Testing
- Stool Culture
- Ova & Parasite Testing
- Clostridium Difficile Testing
Clues to bacterial etiology causing stool issues
- 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
Leukocyte and lactoferrin testing
- 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
Stool culture
Inpatient setting indications
- 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
Salmonella gold standard testing
Do most pts w/this require treatment?
Stool culture
Require no treatment - tx symptomatically
Treat: severe disease, immunocompromised, Type A typhoid fever
Campylobacter
- Can look similar to salmonella and tx similar to salmonella
- Stool culture gold standard
- Fecal-oral
- From undercooked chicken
Shigella
- Often inflammatory
- Frequent diarrhea, tenesmus
- Fecal-oral transmission - water/food
- Stool culture gold standard
E. coli
- Fecal-oral
- Diarrhea, abd cramping, sometimes bloody diarrhea
- Beware of abx use!!
Shiga-toxin producing E. coli
- 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
Indications for Ova & Parasite testing
- > 7d + associated with
- Infant in daycare (giardia)
- Waterborne outbreaks (giardia)
- Travel to developing countries
- Immunocompromised (I.e. HIV)
Giardia infection
- Usually non-inflamm
- (-) fever
- Fecal-oral transmission via contaminated water
- gold standard test: stool ova & parasite testing
Traveler’s diarrhea workup
- Uncomplicated cases do not require any workup and only supportive/symptomatic tx → typically resolve w/in 5d
- Do not give abx
C. difficile
- 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
C. Difficile testing options
Lab approach to dx of C. diff (picture slide 38)
- 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
Indications for abdominal x-ray
What to check-off when looking
- 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!
Abd x-ray free air interpretation
- Perforation!!!
- Caused by trauma, infection, ruptured ulcer, obstruction, foreign body
- Visible under diaphragm when upright
Abd x-ray obstruction interpretation
- 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
