Immediate Skin Test Flashcards
Type on Gel and Coombs
Type I
Type I vs Type IV
Type I - IgE mediated
Type IV - T cell mediated
contraindications to Type I Skin Test
Severe asthma attack in past two weeks antihistamines pregnancy longtime steroid use beta blockers certain chronic medical conditions
Prick Advantage
Safer than ID Minimal systemic absorption faster less tedious for tech Less discomfort for patient
Disadvantage of skin prick test
cross contamination
cross reaction
Prick Skin Test Positive Control
Histamine 2.75mg/mL
Prick Skin Test Negative Control
Diluent used in extract
- HSA
- Glycerin
Extract Strengths prick test
10,000-20,000 pnu/mL
1:10 or 1:20 w/v
Types of prick device
Dermapick (plastic)
Quintip (metal)
How long after skin test do you read?
15 minutes
Dermapick vs Quintip placement
Dermapick - 45 degress
Quintip - 90 degress
how is prick skin written
wheal x flare by widest size
What is often considered postive on test?
3mm +
Must be determined by physician
What if negative control has wheal and flare of 3mm?
adding requirement that allergent test have wheal size of 3mm more than negative control
false postive reactions
technician error
- excessive strength of antigen admin
- excessive dose
- cross contamination
dermagraphic skin
