Implications of placental pathology for disease mechanisms; methods, issues and future approaches

Pathological examination of the placenta is a well-established investigation following delivery in order to investigate the underlying mechanisms of a range of pregnancy related complications. Several recommendations and guidelines are available regarding the indications for such placental testing. The immediate clinical rationale for this process is to identify underlying disease processes which may have an impact on the management of either the infant or the mother in future pregnancies. Additional benefits include improved understanding of the pathophysiological processes of disease and potential medicolegal implications in cases with adverse outcome, including regarding possible timing of lesions. However, interpretation of findings in specific cases remains difficult for several methodological reasons. Future progress requires the use of high quality, well phenotyped tissue collections, with blinded assessment using consensus criteria. In addition, it is likely that novel discovery-based approaches will significantly change the concept of how placental disease is investigated, making tissue sampling even more important across a wide range of pregnancy-related diseases. This will be associated with more stringent conditions for placental evaluation and sampling, including strict definitions of sample site and interval post-delivery, the effects of which will vary depending on the precise assays and methodologies used.