Redline et al described histologic features of the Amniotic Infection Syndrome (AIS) separating maternal and fetal responses. The authors are from University Hospitals of Cleveland and Case Western Reserve University in Cleveland.
Parameters:
(1) stage – histologic extent of maternal disease
(2) grade – intensity of inflammation
Histologic Distribution of Neutrophilic Inflammation
Stage
(no excess) OR (0 with > 10 PMN in subchorionic fibrin)
0
>= 1 microscopic field with > 10 PMNs in subchorionic fibrin BUT NOT (inflammation in chorion or amnion)
1
(neutrophilic inflammation of chorionic plate and/or extraplacental membrane chorion and amnion) BUT NOT (karyorrhexis and/or necrotizing inflammation)
2
(neutrophilic inflammation of chorionic plate and/or extraplacental membrane chorion and amnion) AND (karyorrhexis and/or necrotizing inflammation)
3
where:
• This could be modified with one stage between 2 and 3 as involvement of chorion and amnion increases.
Maximum Number of Neutrophils
Grade
1 to 10 per high powered field
1
11 to 30 per high powered field
2
31 to 100 per high powered field
3
> 100 per high powered field
4
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