Morphometry of the Basal Plate Superficial Uteroplacental Vasculature in Normal Midtrimester and at Term CAROLYN M. SALAFIA, 1,2,3 *JOHN C. PEZZULLO, 1 ADRIAN K. CHARLES, 4 LINDA M. ERNST , 5 ELIZABETH M. MAAS, 1 BENITA GROSS, 2 AND ROBERT PIJNENBORG 6 1 Early Path Pathology Services, 86 Edgewood Avenue, Larchmont, NY 10538, USA 2 Department of Epidemiology, Mailman School of Public Health, 722 West 168th Street, New York, NY 10032, USA 3 Department of Obstetrics and Gynecology, Bronx-Lebanon Concourse Division, 1650 Grand Concourse, Bronx, NY, USA 4 Department of Pathology, King Edward Memorial Hospital for Women, 374 Bagot Road Subiaco, Western Australia, Australia 6008 5 Children's Hospital of Philadelphia, 34th and Civic Center Boulevard, Philadelphia, PA 19104, USA 6 Department of Obstetrics and Gynecology, Universitair Ziekenhuis Gasthuisberg, Katholieke Universiteit of Leuven, B300 Leuven, Belgium Received September 9, 2004; accepted March 29, 2005; published online July 14, 2005. ABSTRACT Uteroplacental (UP) vascular arterial pathology has been associated with pregnancy complications. UP arterial structure has been characterized in placental bed biop- sies, at the decidual-myometrial junction. Basal plate UP arteries, which are delivered with the placenta and thus routinely available, are not well characterized. We compared basal plate UP arterial segment morphometry in cases of elective termination of a clinically normal pregnancy at 11 to 24 weeks and of term birth. This study was done in a community-based obstetric service in New York City. UP arteries were identified in placentas of 20 midtrimester (MT) cases and 17 term (TERM) cases. We measured 336 UP artery cross-sections from 46 TERM and 290 MT cases. The basal plate UP artery path length was calculated as the distance between (x,y) coordinates of estimated centers of lumen cross-sections. Basal plate thickness near UP arteries, UP artery cross-sectional areas, vascular luminal eccentricity, and radial standard deviation were directly measured off digital images. Nonparametric and parametric methods compared groups, with P < 0.05 considered statistically significant. In TERM cases, the basal plate thickness near UP ar- teries was 1.8-fold thinner (P = 0.002) and mean basal plate path lengths were 2.13-fold shorter (P < 0.0001) than in MT cases. Mean TERM UP artery cross-sectional area was 3.15-fold larger, the major axis was 1.95-fold larger, and the minor axis was 1.75-fold larger than in MT arteries (P = 0.001 to 0.008). Our data demonstrate that basal plate UP arteries (delivered with the placenta) are less tortuous, with shorter path lengths and larger areas as gestation advances. Normative morphometric data may allow improved diagnostics of placentas from complicated pregnancies. Key words: placenta, uteroplacental vasculature, mor- phometry, midtrimester INTRODUCTION Maternal and uteroplacental (UP) vascular arterial pathologies have been suggested to underlie a wide range of obstetric complications, from early This work was presented in part at the 51st Annual Meeting of the Society for Gynecologic Investigation; Washington, DC; March 28–30 2003. *Corresponding author, e-mail: salafiacm@aol.com Pediatric and Developmental Pathology 8, 639–646, 2005 DOI: 10.1007/s10024-005-0409-9 ª 2005 Society for Pediatric Pathology