"Delayed Villous Maturation" in Placental Reporting: Concordance amongst Consultant Paediatric Pathologists at a Single Specialist Centre

Abstract

Delayed villous maturation (DVM) has been associated with an increased risk of adverse pregnancy outcome, including stillbirth, in the late third trimester, but there are limited published data. Moreover, it is recognised that the assessment of villous maturation is subjective and hampered by both intra- and interobserver variability. This audit aims to assess concordance in the reporting of DVM among paediatric pathologists at a single specialist centre in order to improve reproducibility of this potentially important diagnosis. A retrospective review of singleton placentas from pregnancies at 35 weeks gestation or above submitted for histopathological examination between June-December 2013. Placental slides were reviewed independently by all four paediatric pathologists,, blinded to the original report apart from gestational age; villous maturation was assessed as appropriate, accelerated or delayed for the stated gestational age. A total of 464 placental histopathology reports were reviewed, of which 164 were more than 35 weeks gestation; of these, 42 (26%) were originally reported as DVM. Following the audit slide review, a total of 38 cases (23%) were assessed to show DVM by at least one pathologist. Consensus, with at least three pathologists agreeing to a diagnosis of DVM, was achieved in only 14 cases (9% of all cases reviewed; 37% of all cases called DVM). However, the proportion of overall agreement between two of the pathologists was 0.92. Concordance for DVM is poor amongst pathologists and subject to much interobserver variability. Consistency may be improved with stringent application of the diagnostic criteria.