Laminar necrosis of placental membranes: a histologic sign of uteroplacental hypoxia

Behind the Curtain of Abnormal Placentation in Pre-Eclampsia: From Molecular Mechanisms to Histological Hallmarks

Successful human pregnancy needs several highly controlled steps to guarantee an oocyte's fertilization, the embryo's pre-implantation development, and its subsequent implantation into the uterine wall. The subsequent placenta development ensures adequate fetal nutrition and oxygenation, with the trophoblast being the first cell lineage to differentiate during this process. The placenta sustains the growth of the fetus by providing it with oxygen and nutrients and removing waste products. It is not surprising that issues with the early development of the placenta can lead to common pregnancy disorders, such as recurrent miscarriage, fetal growth restriction, pre-eclampsia, and stillbirth. Understanding the normal development of the human placenta is essential for recognizing and contextualizing any pathological aberrations that may occur. The effects of these issues may not become apparent until later in pregnancy, during the mid or advanced stages. This review discusses the process of the embryo implantation phase, the molecular mechanisms involved, and the abnormalities in those mechanisms that are thought to contribute to the development of pre-eclampsia. The review also covers the histological hallmarks of pre-eclampsia as found during the examination of placental tissue from pre-eclampsia patients.

Outcome-Based Risk Stratification Model for the Diagnosis of Placental Maternal Vascular Malperfusion

The Amsterdam Consensus Statement introduced the term maternal vascular malperfusion (MVM) to group a constellation of findings associated with impaired maternal-placental circulation. In isolation, these findings are relatively common in placentas from normal gestations, and there is uncertainty on how many, and which, are required. We aimed to determine the criteria essential for MVM diagnosis in correlation with obstetrical outcomes. A total of 200 placentas (100 with a reported diagnosis of MVM and 100 controls matched by maternal age and gravida-para-abortus status) were reviewed to document MVM features. Obstetrical outcomes in the current pregnancy were recorded including hypertension, pre-eclampsia with or without severe features, gestational diabetes, prematurity, fetal growth restriction, and intrauterine fetal demise. On univariate logistic regression analysis, adverse outcome was associated with low placental weight (LPW, <10% percentile for gestational age), accelerated villous maturation (AVM), decidual arteriopathy (DA), infarcts (presence and volume), distal villous hypoplasia, and excess multinucleated trophoblast in basal plate ≥2 mm (all P < .01) but not with retroplacental hemorrhage. In a multivariable model DA, infarcts and AVM were significantly associated with adverse outcomes, whereas LPW showed a trend toward significance. A receiver-operating characteristic curve including these 4 parameters showed good predictive ability (area under the curve [AUC], 0.8256). Based on the probability of an adverse outcome, we recommend consistent reporting of DA, AVM, infarcts, and LPW, summarizing them as "diagnostic of MVM" (DA or AVM plus any other feature, yielding a probability of 65%-97% for adverse obstetrical outcomes) or "suggestive of MVM" (if only 1 feature is present, or only 2 features are infarcts plus LPW, yielding a probability of up to 52%). Other features such as distal villous hypoplasia, excess (≥2 mm) multinucleated trophoblast, and retroplacental hemorrhage can also be reported, and their role in MVM diagnosis should be further studied.

Shallow Placentation: A Distinct Category of Placental Lesions

OBJECTIVE

Shallow placental implantation (SPI) features placental maldistribution of extravillous trophoblasts and includes excessive amount of extravillous trophoblasts, chorionic microcysts in the membranes and chorionic disc, and decidual clusters of multinucleate trophoblasts. The histological lesions were previously and individually reported in association with various clinical and placental abnormalities. This retrospective statistical analysis of a large placental database from high-risk pregnancy statistically compares placentas with and without a composite group of features of SPI.

STUDY DESIGN

Twenty-four independent abnormal clinical and 44 other than SPI placental phenotypes were compared between 4,930 placentas without (group 1) and 1,283 placentas with one or more histological features of SPI (composite SPI group; group 2). Placentas were received for pathology examination at a discretion of obstetricians. Placental lesion terminology was consistent with the Amsterdam criteria, with addition of other lesions described more recently.

RESULTS

Cases of group 2 featured statistically and significantly (p < 0.001after Bonferroni's correction) more common than group 1 on the following measures: gestational hypertension, preeclampsia, oligohydramnios, polyhydramnios, abnormal Dopplers, induction of labor, cesarean section, perinatal mortality, fetal growth restriction, stay in neonatal intensive care unit (NICU), congenital malformation, deep meconium penetration, intravillous hemorrhage, villous infarction, membrane laminar necrosis, fetal blood erythroblastosis, decidual arteriopathy (hypertrophic and atherosis), chronic hypoxic injury (uterine and postuterine), intervillous thrombus, segmental and global fetal vascular malperfusion, various umbilical cord abnormalities, and basal plate myometrial fibers.

CONCLUSION

SPI placentas were statistically and significantly associated with 48% abnormal independent clinical and 51% independent abnormal placental phenotypes such as acute and chronic hypoxic lesions, fetal vascular malperfusion, umbilical cord abnormalities, and basal plate myometrial fibers among others. Therefore, SPI should be regarded as a category of placental lesions related to maternal vascular malperfusion and the "Great Obstetrical Syndromes."

KEY POINTS

· SPI reflects abnormal distribution of extravillous trophoblasts.. · SPI features abnormal clinical and placental phenotypes.. · SPI portends increased risk of complicated perinatal outcome..

Oxidative Stress Markers in Human Brain and Placenta May Reveal the Timing of Hypoxic-Ischemic Injury: Evidence from an Immunohistochemical Study

During pregnancy, reactive oxygen species (ROS) serve as crucial signaling molecules for fetoplacental circulatory physiology. Oxidative stress is thought to sustain the pathogenesis and progression of hypoxic-ischemic encephalopathy (HIE). A retrospective study was performed on the brains and placentas of fetuses and newborns between 36-42 weeks of gestation (Group_1: Fetal intrauterine deaths, Group_2: Intrapartum deaths, Group_3: Post-partum deaths, Control group sudden neonatal death); all groups were further divided into two subgroups (Subgroup_B [brain] and Subgroup_P [placenta]), and the study was conducted through the immunohistochemical investigations of markers of oxidative stress (NOX2, 8-OHdG, NT, iNOS), IL-6, and only on the brain samples, AQP4. The results for the brain samples suggest that NOX2, 8-OHdG, NT, iNOS, and IL-6 were statistically significantly expressed above the controls. iNOS was more expressed in the fetal intrauterine death (Group_1) and less expressed in post-partum death (Group_3), while in intrapartum death (Group_2), the immunoreactivity was very low. IL-6 showed the highest expression in the brain cortex of the fetal intrauterine death (Group_1), while intrapartum death (Group_2) and post-partum death (Group_3) showed weak immunoreactivity. Post-partum death (Group_3) placentas showed the highest immunoreactivity to NOX2, which was almost double that of the fetal intrauterine death (Group_1) and intrapartum death (Group_2) placentas. Placental tissues of fetal intrauterine death (Group_1) and intrapartum death (Group_2) showed higher expression of iNOS than post-partum death (Group_3), while the IL-6 expression was higher in the fetal intrauterine death (Group_1) than the post-partum death (Group_3). The AQP4 was discarded as a possible marker because the immunohistochemical reaction in the three groups of cases and the control group was negative. The goal of this study, from the point of view of forensic pathology, is to provide scientific evidence in cases of medical liability in the Obstetric field to support the clinical data of the timing of HIE.

Synoptic Reporting in Clinical Placental Pathology: A Preliminary Investigation Into Report Findings and Interobserver Agreement

INTRODUCTION

Placental pathology is key for investigating adverse pregnancy outcomes, however, lack of standardization in reporting has limited clinical utility. We evaluated a novel placental pathology synoptic report, comparing its robustness to narrative reports, and assessed interobserver agreement.

METHODS

100 singleton placentas were included. Histology slides were examined by 2 senior perinatal pathologists and 2 pathology residents using a synoptic report (32 lesions). Historical narrative reports were compared to synoptic reports. Kappa scores were calculated for interobserver agreement between senior, resident, and senior vs resident pathologists.

RESULTS

Synoptic reporting detected 169 (51.4%) lesion instances initially not included in historical reports. Amongst senior pathologists, 64% of all lesions examined demonstrated fair-to-excellent agreement (Kappa ≥0.41), with only 26% of Kappas ≥0.41 amongst those examined by resident pathologists. Well-characterized lesions (e.g., chorioamnionitis) demonstrated higher agreement, with lower agreement for uncommon lesions and those previously shown to have poor consensus.

DISCUSSION

Synoptic reporting is one proposed method to address issues in placenta pathology reporting. The synoptic report generally identifies more lesions compared to the narrative report, however clinical significance remains unclear. Interobserver agreement is likely related to differential in experience. Further efforts to improve overall standardization of placenta pathology reporting are needed.

Placental lesions attributed to shallow implantation, excess extravillous trophoblast and decidual hypoxia: Correlation with maternal vascular malperfusion and related obstetric conditions

INTRODUCTION

Maternal vascular malperfusion (MVM) is one of four main patterns of placental injury defined by the Amsterdam consensus statement and is associated with adverse fetal and maternal outcomes. Laminar decidual necrosis (DLN), extravillous trophoblast islands (ETIs), placental septa (PS), and basal plate multinucleate implantation-type trophoblasts (MNTs) are lesions attributed to decidual hypoxia, excess trophoblast, and shallow implantation, but are not included in the current MVM diagnostic criteria. We aimed to investigate the relationship between these lesions and MVM.

METHODS

A case-control model was used to evaluate for DLN, ETIs, PS, and MNTs. Placentas with MVM on pathologic examination (defined as ≥2 related lesions) constituted the case group, and maternal age- and GPA-status-matched placentas with less than 2 lesions constituted the control group. MVM-related obstetric morbidities were recorded, including hypertension, preeclampsia, and diabetes. These were correlated with the lesions of interest.

RESULTS

200 placentas were reviewed: 100 MVM cases and 100 controls. MNTs and PS showed significant enrichment in the MVM group (p < .05). Furthermore, larger foci of MNTs (>2 mm linear extent) were significantly associated with chronic or gestational hypertension (OR = 4.10; p < .05) and preeclampsia (OR = 8.14; p < .05). DLN extent correlated with placental infarction, but DLN and ETIs (including size and number) lacked association with MVM-related clinical conditions.

DISCUSSION

As a marker of abnormally shallow placentation and related maternal morbidities, MNT merits inclusion within the MVM pathologic spectrum. Consistent reporting of MNTs >2 mm in size is recommended, as these lesions correlate with other MVM lesions and MVM-predisposing morbidities. Other lesions, particularly DLN and ETI, lacked such association questioning their diagnostic utility.

Life After Amsterdam: Placental Pathology Consensus Recommendations and Beyond

The Amsterdam Placental Workshop Group Consensus Statement on Sampling and Definitions of Placental Lesions has become widely accepted and is increasingly used as the universal language to describe the most common pathologic lesions found in the placenta. This review summarizes the most salient aspects of this seminal publication and the subsequent emerging literature based on Amsterdam definitions and criteria, with emphasis on publications relating to diagnosis, grading, and staging of placental pathologic conditions. We also provide an overview of the recent expert recommendations on the pathologic grading of placenta accreta spectrum, with insights on their clinical context. Finally, we discuss the emerging entity of SARS-CoV2 placentitis.

Laminar Necrosis and Hypoxic Damage of the Placenta: A Case-Control Study

The aim of this study is to verify the role of laminar necrosis (LN) in the diagnosis of hypoxic damage of the placenta. This is a retrospective case-control study in which 50 cases with laminar necrosis were compared with 100 gestational age-matched controls without laminar necrosis in a 1:2 ratio. The parameters analyzed were: the presence of other placental lesions, obstetric characteristics and neonatal outcome. For each of the 50 cases, the area affected by the lesion was detected, and the lesions were classified into three groups based on the morphology and time of onset of the lesion in order to understand whether these characteristics of the lesion had a clinical-pathology. The results showed that including the search for LN among placental lesions generally examined is useful to guide the pathologist in the diagnosis of placental dysfunction of hypoxic origin.

Disorders of placental villous maturation are present in one-third of cases with spontaneous preterm labor

OBJECTIVES

Spontaneous preterm labor is an obstetrical syndrome accounting for approximately 65-70% of preterm births, the latter being the most frequent cause of neonatal death and the second most frequent cause of death in children less than five years of age worldwide. The purpose of this study was to determine and compare to uncomplicated pregnancies (1) the frequency of placental disorders of villous maturation in spontaneous preterm labor; (2) the frequency of other placental morphologic characteristics associated with the preterm labor syndrome; and (3) the distribution of these lesions according to gestational age at delivery and their severity.

METHODS

A case-control study of singleton pregnant women was conducted that included (1) uncomplicated pregnancies (controls, n=944) and (2) pregnancies with spontaneous preterm labor (cases, n=438). All placentas underwent histopathologic examination. Patients with chronic maternal diseases (e.g., chronic hypertension, diabetes mellitus, renal disease, thyroid disease, asthma, autoimmune disease, and coagulopathies), fetal malformations, chromosomal abnormalities, multifetal gestation, preeclampsia, eclampsia, preterm prelabor rupture of the fetal membranes, gestational hypertension, gestational diabetes mellitus, and HELLP (hemolysis, elevated liver enzymes and low platelet count) syndrome were excluded from the study.

RESULTS

Compared to the controls, the most prevalent placental lesions among the cases were the disorders of villous maturation (31.8% [106/333] including delayed villous maturation 18.6% [62/333] vs. 1.4% [6/442], q<0.0001, prevalence ratio 13.7; and accelerated villous maturation 13.2% [44/333] vs. 0% [0/442], q<0.001). Other lesions in decreasing order of prevalence included hypercapillarized villi (15.6% [68/435] vs. 3.5% [33/938], q<0.001, prevalence ratio 4.4); nucleated red blood cells (1.1% [5/437] vs. 0% [0/938], q<0.01); chronic inflammatory lesions (47.9% [210/438] vs. 29.9% [282/944], q<0.0001, prevalence ratio 1.6); fetal inflammatory response (30.1% [132/438] vs. 23.2% [219/944], q<0.05, prevalence ratio 1.3); maternal inflammatory response (45.5% [195/438] vs. 36.1% [341/944], q<0.01, prevalence ratio 1.2); and maternal vascular malperfusion (44.5% [195/438] vs. 35.7% [337/944], q<0.01, prevalence ratio 1.2). Accelerated villous maturation did not show gestational age-dependent association with any other placental lesion while delayed villous maturation showed a gestational age-dependent association with acute placental inflammation (q-value=0.005).

CONCLUSIONS

Disorders of villous maturation are present in nearly one-third of the cases of spontaneous preterm labor.

Disorders of placental villous maturation in fetal death

Objective The aims of this study were to ascertain the frequency of disorders of villous maturation in fetal death and to also delineate other placental histopathologic lesions in fetal death. Methods This was a retrospective observational cohort study of fetal deaths occurring among women between January 2004 and January 2016 at Hutzel Women's Hospital, Detroit, MI, USA. Cases comprised fetuses with death beyond 20 weeks' gestation. Fetal deaths with congenital anomalies and multiple gestations were excluded. Controls included pregnant women without medical/obstetrical complications and delivered singleton, term (37-42 weeks) neonate with 5-min Apgar score ≥7 and birthweight between the 10th and 90th percentiles. Results Ninety-two percent (132/143) of placentas with fetal death showed placental histologic lesions. Fetal deaths were associated with (1) higher frequency of disorders of villous maturation [44.0% (64/143) vs. 1.0% (4/405), P < 0.0001, prevalence ratio, 44.6; delayed villous maturation, 22% (31/143); accelerated villous maturation, 20% (28/143); and maturation arrest, 4% (5/143)]; (2) higher frequency of maternal vascular malperfusion lesions [75.5% (108/143) vs. 35.7% (337/944), P < 0.0001, prevalence ratio, 2.1] and fetal vascular malperfusion lesions [88.1% (126/143) vs. 19.7% (186/944), P < 0.0001, prevalence ratio, 4.5]; (3) higher frequency of placental histologic patterns suggestive of hypoxia [59.0% (85/143) vs. 9.3% (82/942), P < 0.0001, prevalence ratio, 6.8]; and (4) higher frequency of chronic inflammatory lesions [53.1% (76/143) vs. 29.9% (282/944), P < 0.001, prevalence ratio 1.8]. Conclusion This study demonstrates that placentas of women with fetal death were 44 times more likely to present disorders of villous maturation compared to placentas of those with normal pregnancy. This suggests that the burden of placental disorders of villous maturation lesions is substantial.

Histological Features of Shallow Placental Implantation Unify Early-Onset and Late-Onset Preeclampsia

Preeclampsia is distinguishable from other hypertensive conditions of pregnancy by its high rates of decidual arteriopathy, the uterine type of chronic hypoxic placental injury, the occurrence of villous infarctions, and clusters of multinucleate trophoblasts in the maternal floor. To retrospectively study the clinical and placental phenotypes of 230 women with early-onset preeclampsia, 261 women with late-onset preeclampsia, and 5059 women without hypertension in pregnancy (comparative group), 24 clinical and 46 placental phenotypes were statistically compared (analysis of variance, χ² with Bonferroni correction). The frequency of decidual arteriopathy (both hypertrophic and atherosis), patterns of chronic hypoxic placental injury, villous infarction, membrane laminar necrosis, membrane microscopic chorionic pseudocysts, clusters of maternal floor multinucleated trophoblasts, excessive number of extravillous trophoblasts, and intervillous thrombi was strikingly higher in both late-onset preeclampsia and early-onset preeclampsia than in the comparative group without hypertension in pregnancy. All 3 patterns of chronic hypoxic placental injury were 2- to 3-fold more common in preeclampsia. Although the preuterine pattern was as common in early-onset preeclampsia as it was in late-onset preeclampsia, the postuterine pattern was 2-fold more common in early-onset preeclampsia, and chronic villitis of unknown etiology was more common in late-onset preeclampsia than in the other 2 groups. Features of shallow placental implantation occurred at the same frequency in early-onset preeclampsia as in late-onset preeclampsia, which reflects an underlying common pathological mechanism in both subgroups of preeclampsia, while hypoxic lesions and patterns of placental injury were more common in early-onset preeclampsia than in late-onset preeclampsia, which correlates with more severe clinical outcomes of the former.

Classification of Preterm Birth With Placental Correlates

Premature birth lacks a widely accepted classification that unites features of the clinical presentation with placental pathology. To further explore associations between the clinical categories of preterm birth and placental histology, 109 infants with gestational age <34 weeks and birth weight <2000 g were selected and, based on electronic records, were classified into preterm birth categories of preterm labor, prelabor premature rupture of membranes, preeclampsia, indicated preterm birth for maternal factors (other than preeclampsia), indicated preterm birth for fetal factors, and the clinical diagnosis of abruption. Corresponding placentas were analyzed for gross and microscopic variables, with findings grouped into categories of amniotic fluid infection, lymphocytic inflammation, maternal vascular malperfusion, and fetal vascular malperfusion. Placental features of maternal vascular malperfusion were pervasive in all preterm birth categories and were commonly associated with amniotic fluid infection and lymphocytic inflammation. Features of maternal vascular malperfusion were significantly associated with preterm birth due to preeclampsia, and amniotic fluid infection was highly associated with prelabor preterm rupture of membranes. Findings of lymphocytic inflammation were significantly increased in cases of abruption. Laminar decidual necrosis was present in all cases of abruption. Placentas from multiple gestations had significantly less histologic findings compared to singletons. Given that 75% of placentas demonstrated at least 1 feature of maternal vascular malperfusion despite different clinical presentations, seemingly different pathologies such as ascending amniotic fluid infection or lymphocytic inflammation may be mechanistically related to processes established early in pregnancy. The concept of "uterine ischemia" may be too simplistic to account for all of the changes attributed to maternal vascular malperfusion in the preterm placenta.

Defense and infection of the human placenta

The placenta functions as a shield against infection of the fetus. The innate and adaptive immune defenses of the developing fetus are poorly equipped to fight infections. Infection by bacteria, viruses, and protozoa may cause infertility, spontaneous abortion, stillbirth, growth retardation, anomalies of development, premature delivery, neonatal morbidity, and mortality. However, appreciation of the human microbiome and host cell-microbe interactions must be taken into consideration as we try to determine what interactions are pathologic. Infection is typically recognized histologically by the presence of inflammation. Yet, several factors make comparison of the placenta to other human organs difficult. The placenta comprises tissues from two persons, complicating the role of the immune system. The placenta is a temporary organ. It must be eventually expelled; the processes leading to partuition involve maternal inflammation. What is normal or pathologic may be a function of timing or extent of the process. We now must consider whether bacteria, and even some viruses, are useful commensals or pathogens. Still, recognizing infection of the placenta is one of the most important contributions placental pathologic examination can give to care of the mother and neonate. This review provides a brief overview of placental defense against infection, consideration of the placental microbiome, routes of infection, and the histopathology of amniotic fluid infection and TORCH infections.

Heme oxygenase-1 deficiency results in splenic T-cell dysregulation in offspring of mothers exposed to late gestational inflammation

PROBLEM

Infection during pregnancy can disrupt regulatory/effector immune system balance, resulting in adverse pregnancy and fetal-neonatal outcomes. Heme oxygenase-1 (HO-1) is a major regulatory enzyme in the immune system. We observed maternal immune response dysregulation during late gestational inflammation (LGI), which may be mediated by HO-1. Here, we extend these studies to examine the immune response of offspring.

METHOD OF STUDY

Pregnant wild-type (Wt) and HO-1 heterozygote (Het) dams were treated with lipopolysaccharide (LPS) or vehicle at E15.5. Pups' splenic immune cells were characterized using flow cytometry.

RESULTS

CD3⁺ CD4⁺ CD25⁺ (Tregs) and CD3⁺ CD8⁺ (Teffs) T cells in Wt and Het were similar in control neonates and increased with age. We showed not only age- but also genotype-specific and long-lasting T-cell dysregulation in pups after maternal LGI. The persistent immune dysregulation, mediated by HO-1 deficiency, was reflected as a decrease in Treg FoxP3 and CD3⁺ CD8⁺ T cells, and an increase in CD4⁺ /CD8⁺ T-cell and Treg/Teff ratios in Hets compared with Wt juvenile mice after maternal exposure to LGI.

CONCLUSION

Maternal exposure to LGI can result in dysregulation of splenic T cells in offspring, especially in those with HO-1 deficiency. We speculate that these immune alterations are the basis of adverse outcomes in neonates from mothers exposed to low-grade (subclinical) infections.

Chorangiosis of Chorionic Villi: What Does It Really Mean?

Chorangiosis has been regarded as a result of low-grade placental hypoxia associated with pregnancy risk factors and abnormal outcomes. It is unknown whether these are a consequence of chorangiosis itself or of associated other placental pathology.Context.—

To prove that chorangiosis itself does not portend an increased risk for pregnancy unless associated with other placental pathology.Objective.—

This retrospective statistical study analyzes 1231 consecutive placentas with diffuse or focal hypervascularity of chorionic villi: 328 with preuterine pattern of chronic hypoxic placental injury (group 1), 297 with uterine type of chronic hypoxic placental injury (group 2), and 606 cases with chorangiosis (group 3) not fulfilling the inclusion criteria for groups 1 or 2.Design.—

Group 2, with 33 cases of chorangiosis (11.1%), featured 10 and 11 statistically significant highest percentages of abnormal clinical and placental variables, respectively; group 3 featured the highest percentages of multiple pregnancy, the heaviest placentas, and the most common acute chorioamnionitis, fetal inflammatory response; and group 1 had the highest proportion of mild erythroblastosis of fetal blood. When comparing groups 1 and 3, 21 of 29 clinical risk factors/outcomes (72.4%) and 30 of 41 placental variables (73.2%) were more common in group 1.Results.—

Presence of diffuse hypoxic patterns of placental injury adds prognostically negative significance to increased vascularity of chorionic villi. Chorangiosis without those patterns portends minimal risk for the pregnancy, and is associated with significantly fewer pregnancy risk factors, abnormal outcomes, and other placental abnormalities.Conclusions.—

Sampling and Definitions of Placental Lesions: Amsterdam Placental Workshop Group Consensus Statement

CONTEXT

-The value of placental examination in investigations of adverse pregnancy outcomes may be compromised by sampling and definition differences between laboratories.

OBJECTIVE

-To establish an agreed-upon protocol for sampling the placenta, and for diagnostic criteria for placental lesions. Recommendations would cover reporting placentas in tertiary centers as well as in community hospitals and district general hospitals, and are also relevant to the scientific research community.

DATA SOURCES

-Areas of controversy or uncertainty were explored prior to a 1-day meeting where placental and perinatal pathologists, and maternal-fetal medicine specialists discussed available evidence and subsequently reached consensus where possible.

CONCLUSIONS

-The group agreed on sets of uniform sampling criteria, placental gross descriptors, pathologic terminologies, and diagnostic criteria. The terminology and microscopic descriptions for maternal vascular malperfusion, fetal vascular malperfusion, delayed villous maturation, patterns of ascending intrauterine infection, and villitis of unknown etiology were agreed upon. Topics requiring further discussion were highlighted. Ongoing developments in our understanding of the pathology of the placenta, scientific bases of the maternofetoplacental triad, and evolution of the clinical significance of defined lesions may necessitate further refinements of these consensus guidelines. The proposed structure will assist in international comparability of clinicopathologic and scientific studies and assist in refining the significance of lesions associated with adverse pregnancy and later health outcomes.

Revisiting decidual vasculopathy

INTRODUCTION

In the setting of preeclampsia (PE), decidual vasculopathy (DV) can be seen along the free membranes.

METHODS

We describe DV using stains for CD31, CD34, Cd42b, CD68, desmin, fibrin and Masson's trichrome in patients with preeclampsia and fetal growth restriction.

RESULTS

We first examined the "membrane roll" sections from the placentas of six patients with preeclampsia. Affected vessels showed endothelial proliferation with detachment. Remodeling of the media was characterized by smooth muscle loss with variable degrees of fibrin deposition. CD31 and CD34 highlighted the prominent endothelium and showed striking particulate staining throughout the media. All of these findings infer a sequence of endothelial injury, fragmentation and repair with incorporation of endothelial components into the vascular wall. We evaluated the frequency of DV by clinical presentation; in cases with PE with and without small for gestational age (SGA) (N = 15), and SGA with and without Doppler flow abnormalities (N = 15). All groups except the SGA without Doppler abnormalities showed DV. Among placentas with DV, the most severely affected group was PE with SGA; the least affected was PE without SGA.

DISCUSSION

The association with SGA suggests that the DV is a subacute process of vascular injury that accelerates in the setting of PE. The majority of DV cases were not initially recognized suggesting a role for endothelial markers for DV detection. We also propose that the rampant endothelial injury seems to be a prominent finding in the decidual vessels of subjects with PE complicated by SGA and a similar process in the systemic vasculature may be responsible for the circulating endothelial microparticles reported in such patients.

Placental hypoxia: the lesions of maternal malperfusion

The placental lesions classically ascribed to placental hypoxia, here denoted maternal malperfusion (MMP), are among the more significant that a placental pathologist may encounter. Yet the appearance of these lesions may be subtle, and the clinical implication of their diagnosis is frequently unclear. The aim of this review is to provide a more nuanced perspective on the clinical utility of placental pathology for the detection of MMP. The review will first detail MMP lesions in the placenta and discuss their associations with pregnancy complications. The review will then delve into the diagnostic and interpretive difficulties of these lesions. Finally, recent research findings that may aid in the development of better diagnostic tools will be briefly discussed.

Is the fetoplacental ratio a differential marker of fetal growth restriction in small for gestational age infants?

Higher placental weight relative to birthweight has been described as an adaptive mechanism to fetal hypoxia in small for gestational age (SGA) infants. However, placental weight alone may not be a good marker reflecting intrauterine growth restriction. We hypothesized that fetoplacental ratio (FPR)-the ratio between birthweight and placental weight-may serve as a good marker of SGA after adjustment for surrogates of fetal hypoxemia (maternal iron deficiency anemia, smoking and choriodecidual necrosis). We conducted a within-sibling analysis using data from the US National Collaborative Perinatal Project (1959-1966) of 1,803 women who delivered their first two (or more) consecutive infants at term (n = 3,494). We used variance-component fixed-effect linear regression models to explore the effect of observed time-varying factors on placental weight and conditional logistic regression to estimate the effects of the tertiles of FPRs (1st small, 2nd normal and 3rd large) on the odds of SGA infants. We found placental weights to be 15 g [95 % confidence interval (CI) 8, 23] higher and -7 g (95 % CI -13, -2) lower among women that had anemia and choriodecidual necrosis, respectively. After multivariable adjustment, newborns with a small FPR (1st-tertile ≤7) had twofold higher odds of being SGA (OR 2.0, 95 % CI 1.2, 3.5) than their siblings with a large FPR (3nd-tertile ≥9). A small FPR was associated with higher odds of SGA, suggesting that small FPR may serve as an indicator suggestive of adverse intrauterine environment. This observation may help to distinguish pathological from constitutional SGA.

Complement factor B activation in patients with preeclampsia

Preeclampsia is a leading cause of maternal and fetal morbidity and mortality. Bb, the active fragment of complement factor B (fB), has been reported to be a predictor of preeclampsia. However, conflicting results have been found by some investigators. We hypothesized that the disagreement in findings may be due to the racial/ethnic differences among various study groups, and that fB activation is significant in women of an ethnic minority with preeclampsia. We investigated the maternal and fetal levels of Bb (the activated fB fragment) in pregnant women of an ethnic minority with or without preeclampsia. We enrolled 291 pregnant women (96% of an ethnic minority, including 78% African-American). Thirteen percent of these were diagnosed with preeclampsia. Maternal venous blood was collected from all participants together with fetal umbilical cord blood samples from 154 deliveries in the 291 women. The results were analyzed using the Mann-Whitney U test and multivariate analyses. Maternal Bb levels were significantly higher in the preeclamptic group than in the nonpreeclamptic group. Levels of Bb in fetal cord blood were similar in both groups. Subgroup analyses of African-American patients' results confirmed the study hypothesis that there would be a significant increase in Bb in the maternal blood of the preeclamptic group and no increase in Bb in the fetal cord blood of this group. These results suggest that a maternal immune response through complement fB might play a role in the development of preeclampsia, particularly in African-American patients.

Hypoxic patterns of placental injury: a review

CONTEXT

In utero hypoxia is an important cause of perinatal morbidity and mortality and can be evaluated retrospectively to explain perinatal outcomes, to assess recurrence risk in subsequent pregnancies, and to investigate for medicolegal purposes by identification of many hypoxic placental lesions. Definitions of some placental hypoxic lesions have been applied relatively liberally, and many of them are frequently underreported. Objectives To present a comprehensive assessment of the criteria for diagnosing acute and chronic histologic features, patterns, and lesions of placental and fetal hypoxia and to discuss clinicopathologic associations and limitations of the use thereof. The significance of lesions that have been described relatively recently and are not yet widely used, such as laminar necrosis; excessive, extravillous trophoblasts; decidual multinucleate extravillous trophoblasts; and, most important, the patterns of diffuse chronic hypoxic preuterine, uterine, and postuterine placental injury and placental maturation defect, will be discussed.

DATA SOURCES

Literature review.

CONCLUSIONS

The placenta does not respond in a single way to hypoxia, and various placental hypoxic features should be explained within a clinical context. Because the placenta has a large reserve capacity, hypoxic lesions may not result in poor fetal condition or outcome. On the other hand, very acute, in utero, hypoxic events, followed by prompt delivery, may not be associated with placental pathology, and many poor perinatal outcomes can be explained by an etiology other than hypoxia. Nevertheless, assessment of placental hypoxic lesions is helpful for retrospective explanations of complications in pregnancy and in medicolegal investigation.

Ascending Infection: Acute Chorioamnionitis

Acute chorioamnionitis is a major cause of spontaneous preterm birth, accounting for more than 40% of deliveries complicated by preterm premature rupture of membranes or preterm labor. In the majority of cases, especially in preterm births, acute chorioamnionitis is caused by ascending polymicrobial infection. Recent evidence suggests that in some cases acute chorioamnionitis may have a noninfectious cause. In addition to the nonspecific patterns of conventional acute chorioamnionitis, this article describes characteristic inflammatory patterns indicative of a specific infectious cause. Several inflammatory entities of putative immunologic (noninfectious) etiology are addressed, including eosinophilic/T-cell vasculitis and chronic chorioamnionitis.

Reassessing the clinical significance of chorionic membrane microcysts and linear necrosis

Recent studies have suggested that 2 lesions of the fetal membranes, linear necrosis at the choriodecidual junction and chorionic membrane microcysts, are markers of uteroplacental ischemia. To evaluate this hypothesis, we examined 807 placentas from unselected, consecutive deliveries at a single hospital over approximately 6 months with specific recording of the presence of chorionic microcysts or linear membrane necrosis. Clinical factors that might indicate uteroplacental ischemia were abstracted from the pathology report, including small for gestational age, pregnancy-induced hypertension, meconium macrophages in the membranes, infarctions, and small placenta. We found that both chorionic microcysts and linear membrane necrosis are very common lesions in unselected placentas, involving 28% and 18% of all placentas, respectively. There was no correlation between the presence of chorionic membrane microcysts and any marker of uteroplacental ischemia. Linear necrosis correlated only with the presence of meconium macrophages. We conclude that these membrane changes are not a useful marker of ischemia in an unselected population of placentas. We suggest caution in the interpretation of these findings, to avoid overdiagnosing ischemia or other pathologic processes.

miR-210 targets iron-sulfur cluster scaffold homologue in human trophoblast cell lines: siderosis of interstitial trophoblasts as a novel pathology of preterm preeclampsia and small-for-gestational-age pregnancies

This study was performed to assess the biological significance of miR-210 in preeclampsia and small-for-gestational-age (SGA) pregnancies. Placental miR-210 expression was evaluated by quantitative RT-PCR (RT-qPCR) in the following groups: i) appropriate-for-gestational-age pregnancies (n = 72), ii) preeclampsia (n = 52), iii) SGA (n = 66), and iv)preeclampsia with SGA (n = 31). The effects of hypoxia (1% O(2)) on miR-210 and iron-sulfur cluster scaffold homologue (ISCU) expressions and miR-210 binding to ISCU 3' UTR were examined in Swan 71 and BeWo cell lines. Perls' reaction (n = 229) and electron microscopy (n = 3) were conducted to verify siderosis of trophoblasts. miR-210 expression was increased in preeclampsia and SGA cases and was decreased with birth weight and gestational age. In both cell lines, miR-210 was induced by hypoxia, whereas ISCU expression was decreased. The luciferase assay confirmed miR-210 binding to ISCU mRNA 3' UTR. RNA interference knockdown of ISCU expression in Swan 71, but not in BeWo, cells resulted in autophagosomal and siderosomal iron accumulation and a fourfold decrease of Matrigel invasion (P = 0.004). Placental ISCU expression was decreased in preeclampsia (P = 0.002) and SGA (P = 0.002) cases. Furthermore, hemosiderin-laden trophoblasts were more frequent in the placental bed of preterm preeclampsia and/or SGA births than in control cases (48.7% versus 17.9%; P = 0.004). Siderosis of interstitial trophoblasts is a novel pathological feature of preeclampsia and SGA. The findings herein suggest that ISCU down-regulation by miR-210 perturbing trophoblast iron metabolism is associated with defective placentation.

Inflammatory response in acute chorioamnionitis

Acute chorioamnionitis is the principal antecedent of premature birth and an important contributor to specific neonatal and other complications that may extend throughout subsequent life. A large number of studies have addressed surrogate markers of in-utero inflammation including cytokines, chemokines, pathogen-associated molecular patterns, and elicited host proteins. However, chorioamnionitis means inflammation occurring within the chorioamnion and the only practical direct measure available to assess this finding in most placentas is histopathology. The maternal and fetal inflammatory response to the presence of organisms within the placental membranes, so-called histologic chorioamnionitis, is the focus of this review. The issues addressed are the nature and origin of the eliciting antigen, mode of spread to the placenta, general characteristics of placental immunity, and a specific characterization of the spectrum of pathologic lesions observed in placentas with membrane infection.

Utility of diagnosing various histological patterns of diffuse chronic hypoxic placental injury

To examine the clinicopathologic correlations of three histological patterns of diffuse chronic hypoxic placental injury (preuterine [PR], uterine [UH], and postuterine [PU]), a retrospective statistical analysis of a large 14-year placental database was performed. Of 5097 placentas between 20 and 43 weeks of gestation examined consecutively, 4413 did not feature histological chronic placental hypoxia, while 684 did. In the latter, maternal hypertensive disorders, diabetes mellitus, abnormal cardiotocography and Dopplers, cesarean sections, inductions of labor, and fetal growth restriction, as well as other placental hypoxic lesions and decidual arteriolopathy, were statistically significantly more common than in the remaining placental material. Two hundred eighty-nine PR cases featured the most advanced gestational age and meconium staining; 237 UH cases featured severe preeclampsia, decidual arteriolopathy, villous infarction, membrane laminar necrosis, microscopic chorionic pseudocysts, excessive extravillous trophoblasts, and maternal floor multinucleate trophoblastic giant cells; and 158 PU cases featured the lowest placental weight and the highest prevalence of abnormal Dopplers, umbilical cord compromise, fetal growth restriction, cesarean section rate, and complicated 3rd stage of labor. The specificity of chronic hypoxic patterns of placental injury was much higher than the sensitivity, with the highest specificity for an excessive amount of extravillous trophoblasts. Diagnosing various hypoxic patterns of placental injury by histology may help to clarify the etiopathogenesis of a significant proportion of complications of pregnancy and abnormal fetal or neonatal outcomes. The patterns should help to retrospectively diagnose placental hypoxia, even in clinically unsuspected cases.

Distribution of sugar residues in human placentas from pregnancies complicated by hypertensive disorders

The aim of the study was to investigate the content and distribution of sugar residues in placentas from pregnancies complicated by hypertensive disorders. Placentas from women with uncomplicated pregnancies (group 1), pregnancies complicated by gestational hypertension (group 2), pregnancies complicated by pre-eclampsia (group 3), pregnancies complicated by pre-eclampsia with HELLP syndrome (hemolysis, elevated liver enzymes and low platelets) (group 4) were collected. Lectins: ConA, WGA, PNA, SBA, DBA, UEA I, GNA, DSA, MAA, SNA, in combination with chemical and enzymatic treatments, were used. Data showed a decrease and/or lack of α-d-mannose, α-d-glucose and d-galactose-(β1-4)-N-acetyl-d-glucosamine in placentas from pre-eclampsia and pre-eclampsia with HELLP syndrome compared with control and hypertension cases. N-acetyl-d-galactosamine appeared and/or increased in placentas from hypertensive disorders. A different distribution of various types of sialic acid was observed in placentas from hypertensive disorders compared with the controls. In particular, placentas from pre-eclampsia, with and without HELLP syndrome, lacked the acetylated sialic acid side-chain. These findings demonstrate various alterations of the carbohydrate metabolism in the placentas from pregnancies complicated by different types of hypertensive disorders. This indicates correlation with the placental morpho-functional changes characteristic of these complications and with the degree of clinical severity.

Placental membrane and placental disc microscopic chorionic cysts share similar clinicopathologic associations

Placental membrane microscopic chorionic cysts (MCC) are associated with clinical conditions and placental features of in utero hypoxia. Those occurring in the cell islands, chorionic plate, placental septa, and maternal floor of the chorionic disc have been thought to have degenerative/liquefactive or secretory etiology and no clinical significance. To study the clinical and placental associations of MCC, 24 clinical (maternal and fetal) and 46 gross and microscopic placental features were statistically compared among 266 consecutive cases with MCC (study group, SG) and 656 consecutive placentas without MCC (control group, CG). The SG was further subdivided into (A) 139 placentas with chorionic disc MCC (at least 3 cysts per 1 placental parenchyma section), (B) 93 cases with membrane MCC (at least 3 chorionic lakes per membrane roll), and (C) 34 cases with both membrane and chorionic disc MCC in the same placenta. The SG contained more cases than the CG of diabetes mellitus, fewer cases with preterm premature ruptures of membranes, more multiple pregnancies, less chorioamnionitis, more cases of massive perivillous fibrin deposition, and more cases involving an excessive amount of chorionic disc extravillous trophoblasts. Within the SG, statistically significant differences among SGA, SGB, and SGC groups were found in terms of maternal diabetes mellitus, total perinatal mortality, neonatal mortality, cesarean deliveries, chorioamnionitis, histological meconium staining, chorangiosis, and excessive amount of chorionic disc extravillous trophoblast, respectively. Both membrane and chorionic disc MCC, frequently associated with an excessive amount of extravillous trophoblast, should be regarded as members of the family of extravillous trophoblastic lesions associated with chronic placental hypoxia.

Diagnosing placental membrane hypoxic lesions increases the sensitivity of placental examination

CONTEXT

Two relatively unknown and recently described placental membrane hypoxic lesions (laminar necrosis and microscopic chorionic pseudocysts) have never been compared with time-honored, focal (infarction), and diffuse hypoxic lesions of placental parenchyma.

OBJECTIVE

To compare the effect on placental diagnosis of the above placental membrane hypoxic lesions and chorionic disc hypoxic lesions (infarctions and global hypoxic pattern of placental injury).

DESIGN

Twenty-three clinical (maternal and fetal) and 32 gross and microscopic placental features were retrospectively compared in 4590 placentas from a placental database built during a 13-year period: 168 placentas with at least one hypoxic disc lesion (infarct or global hypoxia) and at least one membrane lesion (microscopic chorionic pseudocysts or laminar necrosis (group 1), 750 placentas with at least one hypoxic villous lesion but no membrane lesion (group 2), 480 placentas with at least one membrane lesion but no villous lesion (group 3), and 3192 placentas with no hypoxic villous or membrane lesions (group 4).

RESULTS

Several clinical and fetal conditions and placental features known to be associated with in utero hypoxia had a statistically significant correlation with the index hypoxic placental lesions, both villous and membranous. Of placentas from patients associated with clinical conditions at risk for hypoxia, 15% featured only hypoxic membrane lesions without a chorionic disc hypoxic lesion.

CONCLUSIONS

Recognizing placental membrane hypoxic lesions increases the sensitivity of placental examination in diagnosing placental hypoxia by at least 15%. The risk of in utero hypoxia is increased when microscopic chorionic pseudocysts and laminar necrosis occur in conjunction with villous hypoxic lesions.

Fetal inflammatory response is often present at early stages of intra-amniotic infection, and its distribution along cord is variable

This study investigates the hypotheses that (1) the fetal inflammatory response to intra-amniotic infection can occur in early stages of maternal inflammatory response and (2) a difference in early cord inflammation exists at different sites in the cord. Placentas accessioned in our department over a 4-year period with a differential in umbilical vessel inflammation between proximal and distal sections were evaluated for cord inflammation using a 0 to 4 graded scale. Cases were also evaluated for acute chorionic vasculitis and extent of maternal inflammatory response. Of 5566 placentas, 1004 (18%) had some degree of cord inflammation; 120 (12%) had a differential in inflammation between the 2 cord sites. Greater cord inflammation was divided almost equally between proximal (59) and distal (61) sections. Twenty-two cases had 1 or both arteries involved in 1 cord section only. The proximal section had the greater degree of inflammation in 21 (95%) of these cases. Early or no maternal inflammatory response was seen in 63 of 120 cases (52%). Acute chorionic vasculitis was identified in 57 of 106 cases (54%) with at least 2 chorionic vessels present. Fetal inflammatory response can be seen in early amniotic infection, occasionally without finding maternal inflammatory response. The absence of differences in cord vein inflammation depending on cord site and the finding that arteritis occurs close to the placental cord insertion site suggest that cord vessel blood flow dynamics play a role in neutrophil margination. At least 2 cord sections representing proximal and distal sites are recommended to exclude fetal inflammatory response.

Acute and chronic placental membrane hypoxic lesions

Laminar necrosis (LN) and microscopic chorionic pseudocysts (MCP) are the two histological placental membrane lesions. This study retrospectively compares the clinical and placental associations of LN and MCP on a large placental material. Four hundred seventy-nine placentae featuring membrane LN (group 1), 220 placentae with MCP (group 2), and 50 placentae with both LN and MCP were identified in the database of consecutively signed by the author 4,853 placentae from 18 to 42 weeks pregnancies in years 1994-2007. Frequencies or averages of several clinical conditions and gross and microscopic placental features were compared among the groups (Yates chi-square or analysis of variance, where appropriate). Statistically significant differences were observed for preeclampsia, diabetes mellitus, stillbirths, cesarean section deliveries, placental weight, gross chorionic cysts, maternal chorioamnionitis, fetal chorioamnionitis, marginate placentae, and excessive amount of extravillous trophoblasts, respectively. Based on the above results, LN, a membrane infarction, appears to be an acute membrane hypoxic lesion, while MCP is a chronic lesion related to a more widespread extravillous trophoblasts accumulation in the placental disk. There was a substantial overlap of other clinical and placental conditions among the groups, paralleling not uncommon coexistence of acute and chronic placental hypoxia, therefore, LN and MCP, in same placentae.

Disorders of placental circulation and the fetal brain

Disorders of the placental circulation, including the release of deleterious mediators to the fetus, are important risk factors for central nervous system complications. These disorders result in discrete patterns of placental injury detectable by a thorough placental pathologic examination. Consideration of the location, severity, multiplicity, and timing of these lesions is critical to a full understanding of their significance. Less than 10% of placentas from term infants that later develop cerebral palsy lack any evidence of placental abnormalities potentially related to adverse outcome.

Amnion nodosum revisited: clinicopathologic and placental correlations

Amnion nodosum is commonly regarded as a placental hallmark of severe and prolonged oligohydramnios. It consists of nodules of amorphous granular material present on the surface of the amnion. We reviewed all 45 cases of amnion nodosum from our placental database from 1994 through 2003 (study group). The control group consisted of 45 cases from the same database matched for gestational age but without amnion nodosum. Oligohydramnios, multiple pregnancy, perinatal mortality, macerated stillbirths, and chronic twin-twin transfusion were the most common clinical features encountered in the study group. Luminal vascular abnormalities of chorionic villi, fibrosis of chorionic villi, and placental edema were the placental features that were more frequently present in the study group.

The Alabama Preterm Birth Study: diffuse decidual leukocytoclastic necrosis of the decidua basalis, a placental lesion associated with preeclampsia, indicated preterm birth and decreased fetal growth

OBJECTIVE

Laminar necrosis, a band-like distribution of coagulative necrosis, has been reported at the choriodecidual interface of the free membranes of placentas of women with various adverse neonatal outcomes. Our goal in this study was to evaluate the frequency of an equivalent feature in the decidua basalis, diffuse decidual leukocytoclastic necrosis (DDLN), a diffuse coagulative necrosis admixed with karyorrhectic debris, in preterm births <32 weeks, and to determine its association with various obstetric conditions, markers of placental inflammation, and newborn outcome.

STUDY DESIGN

Four hundred and forty-six mother/infant dyads who delivered between 23 and 32 weeks gestational age (GA) had their medical records abstracted, a variety of placental and cord blood cultures performed, cord interleukin-6 (IL-6) levels determined, and the placentas evaluated histologically by a single pathologist (OFP).

RESULTS

Women with DDLN (27%) were significantly more likely than other women to have preeclampsia (57.6 vs. 24.8%, p < 0.0001), an indicated preterm birth in this pregnancy (61.9 vs. 26.4%, p < 0.0001), and a prior indicated preterm birth (12.7 vs. 4.1%, p = 0.001), but were not more likely to have an abruption, diabetes, to smoke or be Black. Among DDLN-positive vs. DDLN-negative women, birth weight was significantly lower (1,069 +/- 373 vs. 1,171 +/- 389 g, p = 0.014), despite the GAs being similar (28.6 +/- 2.2 vs. 28.6 +/- 2.3 weeks, p = NS). Women with DDLN were less likely to have a positive placental culture for any organism (50.0 vs. 61.3%p = 0.03), Ureaplasma urealyticum and Mycoplasma hominis in either the placenta or cord blood (29.7 vs. 42.1%, p = 0.02), or an elevated cord blood IL-6 (21.5 vs. 32.9%, p = 0.059). They also were less likely to have acute inflammation of the membranes (27.4 vs. 56.4%, p < 0.0001), chorionic plate (17.0 vs. 48.6%, p < 0.0001) or cord (15.7 vs. 36.6%, p < 0.0001). Decidual necrosis in the free membranes also occurred more frequently in the presence vs. absence of DDLN (25.2 vs. 9.2%, p < 0.0001). Infants whose placentas had DDLN were significantly less likely to have neonatal systemic inflammatory response syndrome (20.7 vs. 35.2%, p = 0.004), but were not significantly different for other neonatal outcomes including respiratory distress syndrome, intraventricular hemorrhage or death.

CONCLUSION

DDLN of the decidua basalis is relatively common in placentas of 23-32 week newborns, and, when present, is inversely associated with inflammatory maternal and newborn conditions and positively associated with preeclampsia, indicated preterm birth, and lower birth weight. The positive correlation of DDLN with obstetrical and neonatal conditions associated with underperfusion of the placental bed, suggests that DDLN may be a marker of vascular compromise.

Microscopic chorionic pseudocysts in placental membranes: a histologic lesion of in utero hypoxia

Grossly apparent and microscopically intermediate trophoblast-lined subchorionic, septal, and cell island cysts are relatively common placental findings. To analyze the clinicopathologic correlations of histologically similar but grossly inapparent microscopic chorionic pseudocysts (lakes) arising in the chorion laeve of placental membranes (mccpm), selected placental and clinical parameters of all 172 consecutive placentas with mccpm (study group, sg) and all consecutive 3743 placentas without mccpm (comparative group, cg) from years 1994 through 2005 were statistically compared; mccpm were observed in 4.3% of all placentas and in 14.9% of placentas from preeclamptic mothers from 24- to 42-week pregnancies, their gestational weeks' distribution almost mirroring that of the distribution of preeclampsia, with a peak in the middle of the 3rd trimester. Microscopic chorionic pseudocysts (lakes) arising in the chorion laeve of placental membranes were statistically significantly more common in patients with preeclampsia and maternal diabetes mellitus. In placentas with mccpm, decidual arteriolopathy, homogeneous placental maturation, global hypoxic pattern of placental injury, chorangiosis, placental infarction, laminar necrosis of membranes, stem obliterative endarteritis, erythroblasts of fetal blood, and decidual hemosiderosis were statistically significantly more common, while acute chorioamnionitis, villous fibrosis, and villous edema were less common (P < or = 0.05). There were no statistically significant differences between sg and cg in meconium staining, retroplacental hematoma, perivillous fibrin deposition, intervillous thrombi, chronic villitis, chorangiomas, placenta accreta, amnion nodosum, and marginate/vallate placenta. Highly statistically significant associations of mccpm with preeclampsia and a cluster of placental lesions known to be linked to placental hypoxia indicate that the mccpm form in response to hypoxia, particularly in patients with preeclampsia; mccpm should therefore be regarded and reported as a hypoxia-associated placental lesion.

The Alabama Preterm Birth Study: intrauterine infection and placental histologic findings in preterm births of males and females less than 32 weeks

OBJECTIVE

The objective of the study was to determine whether there are differences in the placental histology and various markers of infection/inflammation between preterm male and female fetuses.

STUDY DESIGN

The placentas and umbilical cords of 446 infants born at 23 to 32 weeks were examined histologically, cultured for aerobic and anaerobic bacteria and mycoplasmas, and the interleukin-6 levels in cord blood determined.

RESULTS

Male infants were significantly more likely to have positive placental cultures than female infants (63.4% versus 51.8%, P = .01, odds ratio 1.5, 1.0 to 2.4). Cord blood Mycoplasma hominis and Ureaplasma urealyticum infections were marginally more common in male than female fetuses (27.6% versus 19.2%, P = .06, odds ratio 1.7, 0.9 to 2.9), but cord blood interleukin-6 levels were not different between male and female fetuses. The only significant histologic difference between male and female placentas was in decidual lymphoplasmacytic cell infiltration (6.3% versus 0.9%, P = .003, odds ratio 8.3, 1.8 to 39.0). Males had a higher percentage of decidual lymphohistiocytic cell infiltration, but the differences were not significant (11.3% versus 7.4%, P = .160, odds ratio 1.6, 0.8 to 3.2).

CONCLUSION

Male infants were significantly more likely to have positive placental membrane cultures than female infants. Decidual lymphoplasmacytic cell infiltrations were more common in male versus female placentas, confirming a previous observation and suggesting that a maternal immune reaction to fetal tissue may be more common in male fetuses.

Inflammatory responses in the placenta and umbilical cord

Histopathological examination of the placenta is the gold standard for evaluating antenatal inflammatory processes that might influence fetal development. Histological chorioamnionitis develops through a well-characterised stereotyped progression of maternal and fetal cellular stages that vary from patient to patient and are amenable to quantification. Increases in the intensity of these responses and their gradual transformation into a chronic phase are important variables that can adversely affect fetal physiology. Under recognised placental inflammatory lesions affecting the decidua, placental villi and fetal vessels are also potentially informative factors that should be taken into account in the studies of adverse pregnancy outcomes. This review summarises the relationships between aetiology, intensity, duration, characteristics and site of histological placental inflammation and suggests how these data may help to better understand the antenatal environment.

The Alabama Preterm Birth Project: placental histology in recurrent spontaneous and indicated preterm birth

OBJECTIVE

For unknown reasons, a previous preterm birth (PTB) is a major risk factor for PTB in the current pregnancy. Our goal is to evaluate placental histology for clues related to the recurrent nature of PTB.

STUDY DESIGN

Four hundred fifty-seven mother/infant dyads delivering between 23 and 32 weeks were first classified as having a spontaneous (S) or indicated (I) PTB, and then sorted into the following mutually exclusive categories by pregnancy history: 1) nulliparous; 2) having no previous PTB; 3) having any previous IPTB; or 4) having a previous SPTB. The placentas were evaluated for acute inflammation in the free membranes, umbilical cord, and chorionic plate, chronic inflammation in the membranes and decidua basalis, thrombosis in the chorionic plate and umbilical cord, and diffuse decidual leukocytoclastic necrosis (DDLN), a lesion associated with decreased placental perfusion.

RESULTS

Women who had a SPTB were far more likely (85.5 vs 14.4 P < .0001) to have a SPTB in the previous pregnancy, while women with an IPTB were significantly more likely to have had a previous IPTB (89.7 vs 10.3 P < .0001). Nulliparas and women with previous term births each had about 64% SPTB and 36% IPTB. Acute inflammation at any site was present in 73.9% of SPTB versus 8.0% of IPTB (P < .0001). Chorionic plate thrombosis was also more common in SPTB than IPTB (16.2 vs 7.6, P = .01). Chronic inflammation at any site was more common in IPTB than SPTB (21.0 vs 12.7%, P = .02), as was DDLN (46.5 vs 16.1, P < .0001). When classified by SPTB and IPTB in the current pregnancy, the histologic results were not further influenced by the previous pregnancy history.

CONCLUSION

SPTB and IPTB are strongly repetitive. Women with SPTB are significantly more likely to have acute inflammation in the free membranes, chorionic plate, and cord, and chorionic plate thrombosis, while women with an IPTB are significantly more likely to have chronic inflammation and especially DDLN. Past obstetric history does not further influence the placental histology.