Membrane microscopic chorionic pseudocysts are associated with increased amount of placental extravillous trophoblasts

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..

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.

Placenta Creta: A Spectrum of Lesions Associated with Shallow Placental Implantation

Background

On placental histology, placenta creta (PC) ranges from clinical placenta percreta through placenta increta and accreta (clinical and occult) to myometrial fibers with intervening decidua. This retrospective study aimed to investigate the clinicopathologic correlations of these lesions.

Methods

A total of 169 recent consecutive cases with PC (group 1) were compared with 1661 cases without PC examined during the same period (group 2). The frequencies of 25 independent clinical and 40 placental phenotypes were statistically compared between the groups using chi-square test or analysis of variance where appropriate.

Results

Group 1 placentas, as compared with group 2 placentas, were statistically significantly (p < 0.05) associated with caesarean sections (11.2% vs. 7.5%), antepartum hemorrhage (17.7% vs 11.6.%), gestational hypertension (11.2% vs 4.3%), preeclampsia (11.8% vs 2.6%), complicated third stage of labor (18.9% vs 6.4%), villous infarction (14.2% vs 8.9%), chronic hypoxic patterns of placental injury, particularly the uterine pattern (14.8%, vs 9.6%), massive perivillous fibrin deposition (9.5% vs 5.3%), chorionic disc chorionic microcysts (21.9% vs 15.9%), clusters of maternal floor multinucleate trophoblasts (27.8% vs 21.2%), excessive trophoblasts of chorionic disc (24.3% vs 17.3%), segmental fetal vascular malperfusion (27.8% vs 19.9%), and fetal vascular ectasia (26.2% vs 15.2%).

Conclusion

Because of the association of PC with gestational hypertensive diseases, acute and chronic placental hypoxic lesions, increased extravillous trophoblasts in the chorionic disc, chorionic microcysts, and maternal floor trophoblastic giant cells, PC should be regarded as a lesion of abnormal placental implantation and abnormal trophoblast invasion rather than decidual deficiency only.

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.

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.

Clustering of maternal-fetal clinical conditions and outcomes and placental lesions

OBJECTIVE

To identify by an inductive statistical analysis mutually similar and clinically relevant clinicoplacental clusters.

STUDY DESIGN

Twenty-nine maternofetal and 49 placental variables have been retrospectively analyzed in a 3382 case clinicoplacental database using a hierarchical agglomerative Ward dendrogram and multidimensional scaling.

RESULTS

The exploratory cluster analysis identified 9 clinicoplacental (macerated stillbirth, fetal growth restriction, placenta creta, acute fetal distress, uterine hypoxia, severe ascending infection, placental abruption, and mixed etiology [2 clusters]), 5 purely placental (regressive placental changes, excessive extravillous trophoblasts, placental hydrops, fetal thrombotic vasculopathy, stem obliterative endarteritis), and 1 purely clinical (fetal congenital malformations) statistically significant clusters/subclusters. The clusters of such variables like clinical umbilical cord compromise, preuterine and postuterine hypoxia, gross umbilical cord or gross chorionic disk abnormalities did not reveal statistically significant stability.

CONCLUSION

Although clinical usefulness of several well-established placental lesions has been confirmed, claims about high predictability of others have not.

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.

Chorionic disk extravillous trophoblasts in placental diagnosis

To study clinical and placental associations of increased amount of chorionic disk extravillous trophoblast (IAEVT), the frequency of selected clinical and placental parameters of 189 consecutive cases with IAEVT, defined as more than 5 cell islands and/or placental septa per placental section, were compared with those for all remaining 1,006 placentas examined during the same period. IAEVT was statistically significantly associated with preeclampsia, decidual arteriolopathy, placental infarction, and several chronic placental hypoxic lesions (uterine hypoxic pattern of hypoxic placental injury, microscopic chorionic pseudocysts, massive perivillous fibrin deposition, and trophoblastic multinucleated giant cells in decidua) and absence of meconium staining and umbilical cord abnormalities. The amount of chorionic disk extravillous trophoblast is increased in association with clinical conditions and placental lesions associated with chronic hypoxia of uterine origin, ie, placental malperfusion. Counting placental septa and cell islands is a valuable surrogate test of chronic placental hypoxia.

Sensitivity and specificity of finding of multinucleate trophoblastic giant cells in decidua in placentas from high-risk pregnancies

This is a retrospective analysis of sensitivity and specificity of clustered placental basal plate multinucleate trophoblastic giant cells for various clinical conditions and placental lesions associated with fetal and placental hypoxia. Selected clinical and placental parameters of 375 consecutive cases of placentas with clusters of multinucleate trophoblastic giant cell (at least 3 cells with at least 3 nuclei) in the decidua (study group) were compared with all remaining 2674 placentas concurrently studied (control group) in 20-week-or-more high-risk pregnancies. Multinucleate trophoblastic giant cell was found in 12.3% of placentas. The study group had statistically significantly more cases of preeclampsia, abnormal Dopplers, induction of labor, and cesarean sections, with its placentas lighter and with more common other hypoxic lesions than in the control-group placentas. The multinucleate trophoblastic giant cell prevalence negatively correlated with gestational age (R = -0.56), peaking at the turn of the second and the third trimesters of pregnancy and declining afterward, and most strongly correlated with the excessive amount of extravillous trophoblasts in the chorionic disc (R = +0.33). The sensitivity of multinucleate trophoblastic giant cells was, on average, 3 times lower than the specificity, the latter averaging greater than 90%. In conclusion, finding of multinucleate trophoblastic giant cells is not exclusively limited to uteroplacental malperfusion of preeclampsia but is also seen in other types of high-risk pregnancy and in association with other placental hypoxic lesions and patterns. Multinucleate trophoblastic giant cells most likely reflect a premature fusion of extravillous trophoblasts because of several factors, likely including also hypoxia. Being highly specific, finding the multinucleate trophoblastic giant cells is unlikely to give a false-positive result and therefore has high value in retrospectively explaining the perinatal morbidity and mortality.

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.