Variability in Pathologists’ Detection of Placental Meconium Uptake Sarah H. Poggi, M.D., 1,4 Carolyn Salafia, M.D., 3 Sara Paiva, M.D., 1 Nia J. Leak, M.D., 1 John C. Pezzullo, Ph.D., 2 and Alessandro Ghidini, M.D. 1,4 ABSTRACT Placental meconium has been associated with poor perinatal outcomes but the reliability of the diagnosis has not been assessed. Our objective was to assess the interobserver variability in detection of placental meconium uptake. Ten pathologists from two community and four university hospitals reviewed 10 hematoxylin and eosin– stained placental slides that included cases of in utero and in vitro meconium uptake as well as negative controls. Pathologists rated amnion denudation, presence, location, and density of meconium. Results were compared using a kappa score measure of concordance. There was fair concordance in samples with > 50% amnion denudation (k ¼ 0.42), though overall amnion integrity concordance was poor (k ¼ 0.18). Similarly, poor concordance was noted for presence (k ¼ 0.13), location (k ¼ 0.06), and density of meconium staining (k ¼ 0.11). Detection of meconium uptake in placentas is highly variable among a representative group of community and university pathologists. This finding suggests a need for a more objective measure of meconium uptake in placentas. KEYWORDS: Placenta, meconium, pathology, concordance A controversial body of evidence suggests that meconium passage, particularly in the preterm fetus or during labor, is associated with higher risk of poor perinatal outcomes, including 5-minute Apgar score < 7, acidotic umbilical artery pH, and cerebral palsy. 1–3 This has led to the belief that fetal meconium passage may sometimes occur in response to an adverse intra- uterine event that causes fetal stress. Placental uptake of meconium has traditionally been considered an indicator of long-standing presence of meconium in the amniotic cavity, thus it often plays a critical role in the determi- nation of the timing of meconium passage and the interpretation of the causal relationship between intra- uterine events and neonatal status at birth. However, the reliability of the histopathologic diagnosis, which can have significant clinical and medicolegal implications, has not been rigorously assessed. A specific issue that can arise is difficulty distinguishing meconium pigment from blood pig- ment. 4 The issue of inconsistency in general with placental pathology evaluations has been attributed to varying level of experience with placentas as well as nonstandard descriptive terminology. 5 To address this, a study investigated interobserver reliability in 233 abnormal placentas for several diagnoses, includ- ing meconium-related pathology. Weighted kappa statistics indicated excellent agreement for the diag- nosis of meconium-related pathology (k ¼ 0.79). 5 A 1 Department of Obstetrics and Gynecology, Georgetown University Hospital, Washington, DC; 2 Georgetown University Medical Center, School of Nursing and Health Sciences, Washington, DC; 3 Depart- ment of Obstetrics and Gynecology, St. Luke’s Roosevelt Hospital, New York, New York; 4 The Brock Perinatal Diagnostic Center, Inova Alexandria Hospital, Alexandria, Virginia. Address for correspondence and reprint requests: Sarah H. Poggi, M.D., Perinatal Diagnostic Center, Inova Alexandria Hospital, 4320 Seminary Road, Alexandria, VA 22304 (e-mail: sarah.poggi@ inova.org). Am J Perinatol 2009;26:207–210. Copyright # 2009 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1 (212) 584-4662. Received: July 1, 2008. Accepted after revision: July 15, 2008. Published online: November 21, 2008. DOI 10.1055/s-0028-1103030. ISSN 0735-1631. 207