Search

Introduction/objectives: The chorionic plate vessels of the placenta are in direct continuity with the fetal vasculature, suggesting chorionic and fetal angiogenesis may be subjected to similar regulatory mechanisms. In this study, we determined the correlation between chorionic plate vascularization and complications of prematurity, focusing on bronchopulmonary dysplasia (BPD) and other conditions with important microvascular components.Methods: We performed a clinicoplacental analysis of 127 extremely preterm infants (23-28 weeks gestation). Chorionic plate vascularization was assessed by number and density of perforating chorionic vessels (PCVs). Charts were reviewed for relevant maternal and neonatal data, including respiratory, neurologic and gastrointestinal complications of prematurity.Results: The placentas displayed marked variability in number (36-523/placenta) and density of PCVs (0.46-3.74 PC V/cm2). The median PCV density of infants with severe BPD was significantly higher than that of infants without BPD (1.51 PC V/cm2 versus 1.09 PC V/cm2, P < 0.05). Conversely, the frequency of moderate-to-severe BPD was 33% higher in infants with PCV density ≥1.50 PC V/cm2 than in those with PCV density <1.50 PC V/cm2 (56% versus 40%, P < 0.01). There was no correlation with neonatal neurologic or gastrointestinal complications.Conclusion: Chorionic plate vascularization correlates with frequency and severity of BPD, supporting a vascular basis that in part is antenatal in origin. Quantitative assessment of chorionic plate vascularization may allow early identification of preterm infants at high risk for BPD (proposed threshold: PCV density ≥1.50 PC V/cm2). The lack of correlation between chorionic vascularization and neurologic/gastrointestinal complications suggests these conditions may have less important antenatal and/or vascular contributions. [ABSTRACT FROM AUTHOR]

Introduction/objectives: Recent studies suggest redness (color) discordance of the placental basal plate may be a marker for twin anemia-polycythemia sequence (TAPS), a recently described complication of diamniotic-monochorionic twinning characterized by marked intertwin hemoglobin (Hb) discordance in the absence of oligohydramnios-polyhydramnios. In this study, we determined the clinicoplacental and choriovascular correlates of basal plate color discordance in monochorionic twin placentas, and assessed its value as postnatal indicator of TAPS.Methods: We performed a clinicoplacental analysis of 100 consecutive non-TTTS diamniotic-monochorionic twin placentas with available photographic documentation of the basal plate. Basal plate redness was quantified by computer-assisted analysis of digital images and expressed as intertwin color difference ratio (CDR).Results: The CDR ranged between 1.00 and 3.58 (median CDR: 1.14; 90th %ile: 1.98). Compared to twins with low CDR (N = 90), twins with high CDR (≥2.0; N = 10) had significantly higher hemoglobin difference (11.25 g/dL versus 2.55 g/dL) and significantly fewer and smaller artery-to-artery (AA) and artery-to-vein (AV) anastomoses. Apgar scores and birth weights were equivalent in both groups. Among the 10 twin sets with high CDR, six (60%) qualified as TAPS, as defined by intertwin Hb difference >8 g/dL and absent or very small AA and AV anastomoses. Conversely, 6 of 8 (75%) twin sets with TAPS had a CDR ≥ 2.0.Conclusion: Intertwin CDR correlates with intertwin hemoglobin difference and chorionic angioarchitecture. A CDR value ≥ 2.0 (the 90%ile value for CDR derived from the present cohort) has high specificity (96%), but relatively low positive predictive value (60%) as indicator of TAPS, as currently defined. [ABSTRACT FROM AUTHOR]

Introduction/objectives: Gastroschisis has been associated with a characteristic type of amniocyte vacuolization. In this study, we determined the frequency and clinicoplacental correlates of this apparently unique alteration of the amniotic epithelium.Methods: We performed a retrospective clinicopathologic analysis of 74 consecutive cases of isolated gastroschisis. Placental membrane sections were reviewed for presence and extent of amniocyte vacuolization, and immunostained for adipophilin, a lipid droplet-associated protein. Controls included placentas from pregnancies complicated by omphalocele, meconium exposure or chorioamnionitis.Results: A distinct type of diffuse, fine and homogeneous amniocyte vacuolization was present in 15/74 (20%), absent in 41/74 (55%), and equivocal in 18/74 (24%) gastroschisis cases. Similar amniocyte vacuolization was seen in only 1/30 meconium-stained controls, and in none of the other non-gastroschisis controls. Adipophilin immunostaining enhanced the visualization of the cytoplasmic vacuoles and confirmed their lipid nature. Compared to gastroschisis cases without such vacuolization, cases with typical, extensive amniocyte vacuolization had a tendency to lower birth weight percentile (26% versus 40%; P < 0.08), a significantly lower fetal:placental weight ratio (4.72 versus 5.51; P < 0.01), and a significantly higher frequency of associated meconium exposure (14/15 versus 15/41, P < 0.001) and/or chorioamnionitis (8/15 versus 6/41; P < 0.01). The length of hospital stay was equivalent for infants with or without amniocyte vacuolization.Conclusion: Diffuse, fine and homogeneous lipid droplet accumulation in amniocytes is highly characteristic of gastroschisis, but only seen in about 20% of cases. The functional implications of excessive lipid accumulation, and the exact mechanisms underlying the strong association between amniocyte lipid accumulation and chorioamnionitis/meconium exposure in a subset of gastroschisis cases remain undetermined. [ABSTRACT FROM AUTHOR]

Introduction We established reference values for placental weight, birth weight, and fetal:placental weight ratio (FPR) (a possible index of placental functional efficiency) in monochorionic and dichorionic twin gestations. Methods Placental weight, birth weight, and FPR in function of gestational age, cord insertion type and placental sharing were determined in 151 dye-injected diamniotic-monochorionic and 198 double-disc diamniotic-dichorionic twin placentas (25–39 weeks' gestation). Results As expected, FPR values increased with gestational age in both groups. Birth weights and placental weights of monochorionic twins >28 weeks' gestation were significantly lower than those of age-matched dichorionic twins. When stratified per placental weight, the birth weights and FPR values of monochorionic twins were overall lower than those of dichorionic twins within the same placental weight category. However, in the subset of monochorionic twins with small share in unevenly partitioned placentas, birth weights and FPR values per placental weight were similar to those of dichorionic twins, and significantly higher than those of monochorionic twins with larger share or even placental sharing. Cord insertion type did not correlate with birth weight or FPR values per placental weight in either twin type. Discussion Reference values were generated for placental weight, birth weight and FPR in monochorionic and double-disc dichorionic twins. The generally lower FPR per placental weight in monochorionic twins compared with dichorionic twins is suggestive of inherently lower placental functional efficiency in monochorionic gestations. The mechanisms and clinical implications of the apparent differential modulation of FPR/efficiency in monochorionic twins according to placental partitioning remain to be determined. [ABSTRACT FROM AUTHOR]

Abstract: Objective: While endoglin has been implicated in the pathogenesis of various complications in singleton pregnancies, its potential contribution to complications of monochorionic twinning remains largely undetermined. The aim of this study was to determine the correlation between relevant clinical and pathological variables and placental endoglin levels in diamniotic-monochorionic twin pregnancies. Methods: Endoglin expression was studied by immunohistochemistry and Western blot in a prospective cohort of 68 non-TTTS and 7 TTTS monochorionic twin placentas. Placental endoglin levels were correlated with clinical and placental characteristics associated with twin-to-twin transfusion syndrome (TTTS) and selective growth restriction, including birth weight discordance, uneven placental sharing, peripheral cord insertion and choriovascular anatomy. Results: In non-TTTS gestations discordant for these criteria, placental endoglin levels were significantly higher for the twin with smaller birth weight, intrauterine growth restriction, and/or abnormal ultrasound Doppler studies than for the more normal co-twin. Similarly, placental endoglin levels were significantly higher in the placental territory with smaller share and/or peripheral cord insertion in cases discordant for these placental characteristics. In TTTS gestations, placental endoglin levels tended to be higher for donor twins than for recipients. There was no correlation between endoglin levels and superficial choriovascular anastomoses. Conclusions: While the exact functional implications remain to be determined, our findings suggest a strong correlation between unbalanced placental endoglin levels and intertwin growth discordance in monochorionic twins. [Copyright &y& Elsevier]

Abstract: Background: Non-central cord insertion has been associated with diminished chorionic vascular distribution in singleton placentas. The choriovascular correlates of peripheral cord insertion in diamniotic-monochorionic twin placentas remain undetermined. Aim: To study the association between type of cord insertion and choriovascular distribution of both twin territories in diamniotic-monochorionic twin placentas. Design: A prospective cohort of 138 monochorionic placentas was examined at Women and Infants Hospital between 2009 and early 2011. Thirty-five cases (25%), including disrupted placentas, placentas from higher order multiples and placentas from pregnancies complicated by twin-to-twin transfusion syndrome, were excluded. The correlation between cord insertion type and superficial choriovascular distribution was studied in the remaining 103 dye-injected diamniotic-monochorionic placentas. Cord insertion was categorized as paracentral, marginal or velamentous. The choriovascular distribution of each individual twin territory was assessed by analysis of number and density (number per surface area) of perforating chorionic arteries (PCA). Results: In contrast with singleton placentas, there was no correlation between cord insertion type and a twin’s own choriovascular distribution in diamniotic-monochorionic placentas. However, a strong correlation was found between the choriovascular distribution of one twin and the cord insertion type of the opposite twin. For a twin with paracentral or marginal cord insertion, the PCA density was significantly higher if the co-twin had a velamentous cord insertion than if the co-twin had a paracentral cord insertion (P < 0.001 and P < 0.05, respectively). Similarly, the PCA density of a twin with velamentous cord insertion tended to be higher if the co-twin had a velamentous, rather than paracentral cord insertion (P = 0.09). Conclusions: This is the first study to suggest that in diamniotic-monochorionic twin gestations, the choriovascular architecture correlates with the cord insertion type of the co-twin. In general, velamentous cord insertion is associated with expanded choriovascular distribution in the opposite twin territory. Our observations may reflect novel manifestations of twin interdependence in monochorionic pregnancies. [Copyright &y& Elsevier]

Abstract: Up to 21% of diamniotic-monochorionic twin pregnancies are complicated by severe birth weight discordance in the absence of twin-to-twin transfusion syndrome, a serious condition termed ‘selective’ birth weight discordance. While its pathogenesis remains incompletely understood, the development of selective intertwin growth discordance, related to fetal growth restriction of one twin, is generally attributed to aberrant placental characteristics. The aim of this study was to characterize the placental markers of selective birth weight discordance, with special emphasis on the choriovascular architecture. A prospective cohort of 319 consecutive diamniotic/monochorionic twin placentas was examined at Women and Infants Hospital between 2001 and 2009. After exclusion of placentas from pregnancies complicated by twin-to-twin transfusion syndrome (TTTS), monoamniotic, multiple and disrupted placentas, 216 placentas (36 birth weight (BW)-discordant and 180 BW-concordant) formed the subject of this study. Following dye injection, the anatomic characteristics and choriovascular anastomotic patterns of BW-discordant and BW-concordant placentas were compared. The BW-discordant placentas showed significantly higher frequencies of velamentous cord insertion (22% versus 8%, P < 0.001) and uneven placental sharing (56% versus 19%, P < 0.0001) compared with BW-concordant placentas. The frequencies of intertwin AA, VV and AV anastomoses, the net number of AV anastomoses, and the net cross-sectional area of AV anastomoses were similar in both groups. There was no correlation between the frequency of velamentous cord insertion and degree of placental sharing or patterns of choriovascular anastomoses in either group. In conclusion, velamentous cord insertion and uneven placental sharing are the two major placental determinants of selective birth weight discordance in diamniotic-monochorionic twins. The role of the intertwin anastomoses, even when unbalanced, is likely negligible. Elucidation of the mechanisms whereby velamentous cord insertion affects fetal growth may lead to more focused and effective therapeutic strategies for twin and singleton pregnancies complicated by dysregulated fetal growth. [Copyright &y& Elsevier]

Abstract: Twin-to-twin transfusion syndrome (TTTS) is a multifactorial disorder that develops in 9–15% of diamniotic–monochorionic twin gestations. While the pathogenesis of TTTS remains poorly understood, unbalanced deep artery-to-vein (AV) anastomoses have traditionally been implicated in the gradual shift of blood from donor to recipient. The aim of this study was to define the placental markers of twin-to-twin transfusion syndrome, with special emphasis on the deep AV anastomoses. A prospective cohort of 284 consecutive diamniotic/monochorionic twin placentas was examined at Women and Infants Hospital between 2001 and 2008. Following exclusion of monoamniotic, multiple, disrupted and laser-treated placentas, 218 twin placentas (21 TTTS and 197 non-TTTS controls) formed the subject of this study. Placentas were injected with color-coded dyes. Anatomic characteristics and choriovascular anastomotic patterns of TTTS placentas were compared with non-TTTS controls. The TTTS placentas showed significantly higher frequencies of velamentous cord insertion, magistral vascular distribution patterns, uneven placental sharing, absence of AA anastomoses and presence of VV anastomoses. Deep AV anastomoses were identified in ≥95% of TTTS and non-TTTS placentas and were overall more abundant than previously reported. The total and net numbers of AV anastomoses were similar in both groups. However, the net cross-sectional area of AV anastomoses, which also takes into account the caliber of the vessels, was significantly smaller in TTTS placentas. There was no correlation between the direction of the AV imbalance and the twin donor/recipient status. In conclusion, TTTS has distinct placental characteristics, warranting their routine inclusion in the diamniotic–monochorionic placental pathology report. Our findings suggest imbalance of AV anastomoses is not required for the development for TTTS, although their presence, whether balanced or unbalanced, may contribute to the creation or perpetuation of the syndrome. Elucidation of the role of the various placental determinants in diamniotic–monochorionic twin gestations may lead to further refinement of therapeutic strategies. [Copyright &y& Elsevier]

Several recent publications have focused on the association between the occurrence of twin-to-twin transfusion syndrome (TTTS) in diamniotic-monochorionic twins and the presence of a number of selected anatomic placental characteristics (distribution of vascular territory, cord insertion, type and number of inter-twin anastomoses). In contrast, the potential importance of the vascular distribution patterns of the individual twins remains to be elucidated. Based on its gross architectural distribution pattern, chorionic vasculature is traditionally described as disperse, magistral or mixed. The aim of this study was (1) to determine the relative prevalence of these vascular distribution patterns in monochorionic twin placentas, and (2) to correlate these patterns with the presence of TTTS and known anatomic placental features linked to TTTS. The placentas of 89 consecutive diamniotic-monochorionic twins (15 with TTTS, 74 without TTTS), examined at Women and Infants Hospital, were studied. Disperse vascular patterns were seen in 53% of twins, and magistral or mixed patterns in 47%. The prevalence of magistral/mixed vascular patterns was significantly higher in TTTS gestations than in non-TTTS gestations (60% versus 44%, P <0.05) and, in TTTS gestations, much higher in donor twins than in recipient twins (87% versus 33%, P <0.005). A strong association was found between the presence of magistral/mixed patterns and marginal/velamentous cord insertion, low number of inter-twin anastomoses, and uneven distribution of the vascular territories. These findings suggest that the magistral/mixed vascular distribution pattern may represent an important placental architectural feature contributing to the complex pathophysiology of TTTS. [Copyright &y& Elsevier]