Intra- and interobserver agreement and statistical clustering of placental histopathologic features relevant to preterm birth.
OBJECTIVE
Many previous studies of agreement in identifying placental histopathologic lesions have been based on small sample sizes, and none has examined whether individual histologic features cluster robustly together within and between observers.


METHODS
We studied 767 placental specimens from case-control studies of preterm birth and preeclampsia nested within a prospective cohort of pregnant women recruited from 4 large Montreal maternity hospitals. The specimens were fixed, embedded, stained, and examined using a standardized protocol; a 10% random sample (n = 81) was then blindly reexamined at least 6 months later by the same pathologist and a second pathologist.


RESULTS
Intra- and interobserver agreement were high (kappa > or = 0.50) for membrane inflammation, funisitis, and umbilical cord vasculitis, and these 3 features were robustly clustered statistically, consistent with an underlying mechanism of ascending infection. Agreement and clustering were also high or moderate for features of placental underperfusion: infarction, decidual vasculopathy, and syncytial knotting.


CONCLUSIONS
Our results should help researchers to interpret future findings relating placental histopathology to preterm birth, preeclampsia, and other adverse pregnancy outcomes, and to their etiologic determinants and causal pathways.
Kramer
Michael S
MS
Department of Pediatrics, McGill University Faculty of Medicine, Montreal, Quebec, Canada. michael.kramer@mcgill.ca
Chen
Moy Fong
MF
Roy
Indrojit
I
Dassa
Clément
C
Lamoureux
Julie
J
Kahn
Susan R
SR
McNamara
Helen
H
Platt
Robert W
RW
D016022:Case-Control Studies; D002821:Chorioamnionitis / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007238:Infarction / Q000473:pathology; D007239:Infections / Q000453:epidemiology; D015588:Observer Variation; D010920:Placenta / Q000098:blood supply / Q000473:pathology*; D010922:Placenta Diseases / Q000453:epidemiology*; D011225:Pre-Eclampsia / Q000453:epidemiology; D011247:Pregnancy; D047928:Premature Birth; D025341:Principal Component Analysis; D011446:Prospective Studies; D016037:Single-Blind Method; D014470:Umbilical Cord / Q000098:blood supply; D014657:Vasculitis / Q000453:epidemiology