Procedure:
(1) Submit at least 2 samplings of soft tissue for frozen section.
(2) Evaluate the area with the maximum number of neutrophils (excluding areas as listed below).
(3) Count neutrophils in at least 5 high powered fields (40x objective lens).
Neutrophils which do not indicate underlying infection and which should not be counted:
(1) in surface fibrin
(2) perivascular (perioperative)
NOTE: There are 2 ways to interpret the method:
(1) Count the number of high powered fields with >= 5 neutrophils.
(2) Count at least 5 high powered fields and calculate the average number of neutrophils per high powered field.
Interpretation:
• minimum number of neutrophils per high power field: 0
• maximum number: very high
|
Neutrophils per High Power Field
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Predictive Value for Infection
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< 5
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negative predictive value 98%
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5 – 9
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positive predictive value 70%
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>= 10
|
positive predictive value 89%
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from Lester page 41
False negatives:
(1) tissue selection by surgeon
(2) sampling error in selecting tissue for frozen section
(3) failure to identify the appropriate site on frozen section
