The occurrence of an immunopathologic vascular lesion in normal and abnormal pregnancies

Maternal vascular underperfusion: nosology and reproducibility of placental reaction patterns

Placental examination can be a useful tool for specifying the etiology, prognosis, and recurrence risk of pregnancy disorders. The purpose of this study was to test the reliability of a predetermined set of placental reaction patterns seen with maternal vascular underperfusion in the hope that this might provide a useful diagnostic framework for practicing pathologists. Study cases (14 with clinical and pathologic evidence of maternal underperfusion plus 6 controls) were evaluated for the presence or absence of 11 lesions by eight perinatal pathologists. After analysis of initial results, diagnostic criteria were refined and a second, overlapping set of cases was reviewed. The collective sensitivity, specificity, and efficiency of individual assessments for the 11 lesions relative to the group consensus ranged from 74-93% (22/33 > 90%). Reproducibility was measured by unweighted kappa-values and interpreted as follows: < 0.2 poor, 0.2-0.6 fair/moderate, > 0.6 substantial. Kappa values for lesions affecting villi and the intervillous space were increased syncytial knots (any -0.42, severe -0.50), villous agglutination (0.42), increased intervillous fibrin (0.25), and distal villous hypoplasia (0.57). Individual estimates of percent involvement for syncytial knots, intervillous fibrin, and distal villous hypoplasia were correlated with placental and fetal weight for gestational age. Extent of increased intervillous fibrin showed the strongest correlation with both placental weight ( R = -0.64) and fetal weight ( R = -0.45). Kappa values for lesions affecting maternal vessels and the implantation site were acute atherosis (0.50), mural hypertrophy of membrane arterioles (0.43), muscularized basal plate arteries (0.48), increased placental site giant cells (0.54), and immature intermediate trophoblast (0.36). Correlation of maternal vessel and implantation site lesions with the clinical diagnosis of preeclampsia showed that excessive placental site giant cells and immature intermediate trophoblast were more sensitive and efficient predictors, whereas atherosis and muscularized basal plate arteries were more specific. Kappa value for a thin umbilical cord, a possible indicator of fetal volume depletion, was 0.61. Reproducibility for a global impression of maternal vascular underperfusion, taking into account all of the above lesions, was moderate (kappa 0.54) and improved after inclusion of additional pathologic and clinical data (kappa 0.68). Adoption of this clearly defined, clinically relevant, and pathologically reproducible terminology could enhance clinicopathologic correlation and provide a more objective framework for future clinical research.

Correlations of sialomucins and IgA in the maternal serum of primiparous and multiparous subjects at delivery

Attention is drawn to correlations between placental coefficients and maternal serum levels of IgA at delivery in primiparae and multiparae. These correlations associate maternal serum IgA with gestational performance and appear to discriminate between groups which differ in that respect. Similar correlations exist between the placental coefficient and maternal serum seromucoid, with group discrimination preserved in primiparae, but not multiparae. Direct correlations between serum seromucoid and IgA in maternal serum can be attributed to their mutual dependence on the size and state of the feto-maternal interface, and may provide a means of detecting placental insufficiency in multigravidae.

Uteroplacental vasculature

Images

Maternal serum sialomucins during pregnancy and postpartum in patients with pre-eclampsia

The seromucoid fraction of maternal serum glycoproteins is increased in pre-eclampsia and the rise, which is proportional to the severity of the disease, may reflect progressive placental deterioration with increasing trophoblast fragmentation and deportation. The pulmonary lysis of deported trophoblast effects the local release of fetal antigens and thromboplastin in the lungs. The former, which are immunologically inert because they are complexed with maternal serum seromucoid, are released into the peripheral circulation, while the local coagulation hazard presented by the latter is countered by intensified fibrinolytic activity, the products of which are also released into the peripheral circulation. In severe pre-eclampsia the peripheral circulation contains a considerable excess of physically similar proteins derived from the seromucoid fraction and fibrin degradation products, and the conditions which then obtain in the renal glomerulus favour the physical process of coacervation. In that event the mechanism of the origin and development of the renal lesion can be described in purely physical terms.