Cheek-Norgan, E Heidi

Abstract Obstetric training programs typically offer limited formal education on placental pathology; yet, in practice, obstetric providers are expected to incorporate placental pathology findings into the overall evaluation of obstetric complications. In this narrative review, we briefly review pathology classifications and then delve deeper into pathology findings that may change clinical decision‐making, specifically highlighting pathologic lesions with a recurrence risk and recommended management for subsequent pregnancies. Last, we present specific recommendations on how to improve clinical interpretability and utility of placental pathology reports for obstetrical practice.

ObjectivesFetal growth restriction (FGR) is commonly associated with placental dysfunction, increasing perinatal morbidity and mortality. Visualizing placental vessels in utero would be advantageous for identifying functional FGR cause and determining proper management strategies. We aimed to utilize high‐sensitivity ultrasound microvessel imaging (HUMI) for quantifying placental vessel density (VD) in pregnancies diagnosed with FGR.MethodsThis pilot case–control study enrolled subjects in the third trimester with a diagnosis of FGR (n = 40) and gestational age‐matched controls with normal fetal growth (n = 20) at a 2:1 ratio, respectively. The Verasonics Vantage ultrasound system was used to perform HUMI on each participant at one timepoint. Scanning involved randomized singular value decomposition‐based clutter filtering to identify the villous tree, followed by step‐by‐step scanning to acquire 3‐dimensional‐like data. Mean VD was calculated from three ultrasound measurements per subject. Additional clinical and pathology data were also collected and compared.ResultsSixteen participants were utilized to establish the scanning protocol and 2 met exclusion criteria at delivery. Thus, VD was successfully measured on 42 pregnancies scanned at 35 weeks 5 days on average. In FGR (n = 24), placental VD was significantly reduced compared to controls (P < .01). VD measures were as good at predicting FGR as systolic/diastolic (S/D) ratios (area under the curve 0.86 versus 0.80). In a smaller cohort, VD in placentas with a diagnosis of inflammatory villitis (n = 10) by histology showed an increase in VD compared to those without inflammation (P = .01). Low VD was correlated with increased S/D ratios (P = .03).ConclusionsHUMI is useful for identifying altered placental vascularization in utero for FGR. VD may be a valuable indicator for placental health and could lead to improved risk stratification methods considering underlying biology.

Objective To evaluate maternal risk factors associated with chronic villitis of unknown etiology (VUE) and to describe cooccurring placental pathologies. Study Design A retrospective case–control study was conducted using placental pathology records from deliveries ≥ 20 weeks between 2010 and 2018. Cases were placentas with documented chronic villitis without infectious cause, hereafter called VUE. Controls were placentas without this diagnosis, matched to the cases 2:1. Maternal and neonatal demographic and clinical data were collected. Descriptive statistics are reported with Fisher's exact test or a chi-squared test, as appropriate, and multivariable conditional logistic regression was conducted. Results Our study included 352 cases with VUE and 657 controls. A diagnosis of gestational diabetes (p = 0.03) and gestational hypertension (p = 0.06) was 1.5 times more likely to occur in those with a VUE diagnosis. A trend was also seen for chronic hypertension (odds ratio [OR] = 1.7, p = 0.07) and preeclampsia (OR = 1.5, p = 0.09) compared with controls. Placentas with VUE, specifically high-grade VUE, were more likely to be small for gestational age (p = 0.01), and to be diagnosed with other placental findings including lymphoplasmacytic or chronic deciduitis (p < 0.01), maternal (p < 0.01) and fetal vascular malperfusion (p = 0.02), and chorionitis (acute or chronic; p < 0.01). Conclusion Gestational diabetes and hypertension were associated with a diagnosis of VUE, and overall, VUE placentas have more abnormal placental findings compared with control. Understanding VUE risk factors may facilitate prenatal care strategies and counseling to achieve the best outcomes for pregnant patients and their neonates. Key Points