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

TLDR

Placental examination for adverse pregnancy outcomes is limited by sampling and definition differences between laboratories, and ongoing advances in placental pathology may require further refinement of consensus guidelines. The purpose was to develop consensus recommendations for placental sampling, gross descriptors, terminologies, and diagnostic criteria applicable to tertiary and community hospitals and the research community. The mechanism involved a one‑day consensus meeting where pathologists and maternal‑fetal medicine specialists reviewed evidence, identified controversies, and established uniform sampling criteria, gross descriptors, terminologies, and diagnostic criteria, while highlighting topics needing further discussion. The findings include agreed terminology and microscopic descriptions for key placental lesions, and a proposed structure that enhances international comparability and refines the clinical significance of lesions linked to adverse pregnancy and later health outcomes.

Abstract

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