Placental vascular lesions and likelihood of diagnosis of preeclampsia.

OBJECTIVE: To test the hypothesis that a range of severity of placental vascular lesions underlies preeclampsia and that the likelihood of its clinical diagnosis increases with the extent and severity of uteroplacental vascular lesions.
METHODS: Four hundred sixty-five consecutive placentas of singleton, nonanomalous, live-born infants born before 32 weeks' gestation were examined prospectively, and uteroplacental vascular and related villous lesions were assigned a semiquantitative lesion score based on severity and extent of lesions. The summed scores of individual lesions yielded a total uteroplacental vascular lesion score, ranging from 0 to 21, that was correlated with the odds of a clinical diagnosis of preeclampsia, as well as with potential confounders, including maternal age, race, gestational age at delivery, and birth weight centile. Statistical analysis was performed using contingency tables, one-way analysis of variance, multiple logistic regression, and receiver operating characteristic curve. P < .05 was considered significant.
RESULTS: A clinical diagnosis of preeclampsia was present in 78 of 465 (17%) cases. Logistic regression demonstrated that the total uteroplacental vascular lesion score related significantly to the diagnosis of preeclampsia (odds ratio 1.43, 95% confidence interval 1.31, 1.57) and this association was independent of gestational age at delivery and birth weight centile. Preeclampsia was diagnosed in 12 of 284 (4%) cases with no or minimal histologic evidence of placental vascular injury (total score less than 4). Conversely, the diagnosis was not made in 4% of cases despite the presence of extensive placental vascular injury (total score at least 14).
CONCLUSION: The likelihood of clinical diagnosis of preeclampsia before 32 weeks increases with progressive impairment of the uteroplacental circulation. Histopathologic examination of the placenta can be used to confirm the diagnosis of preeclampsia.