Original contribution Thrombosis of the umbilical vessels revisited. An observational study of 317 consecutive autopsies at a single institution Laura Avagliano MD a,b , Anna Maria Marconi MD b, ⁎ , Massimo Candiani MD b , Antonino Barbera MD c , Gaetano Bulfamante MD a a Unit of Human Pathology, Department of Medicine, Surgery and Dentistry, San Paolo Hospital Medical School, University of Milano, 20142 Milano, Italy b Unit of Obstetrics and Gynecology, Department of Medicine, Surgery and Dentistry, San Paolo Hospital Medical School, University of Milano, 20142 Milano, Italy c Department of Obstetrics and Gynecology, Denver Health Medical Center, Denver, CO 80204, USA Received 9 February 2009; revised 10 July 2009; accepted 17 July 2009 Keywords: Thrombosis of the umbilical vessels; Fetal death; Placental histology; Placental basal plate changes Summary Thrombosis of the umbilical vessels has been associated with conditions like fetal death, cerebral palsy, and severe fetal distress, which are common causes for litigation in today's obstetrics practice. Although different anatomical conditions of the umbilical cord as well as maternal or fetal pathologies are considered risk factors, the etiology of thrombosis of the umbilical vessels is still obscure in many cases that pathologists handle. We diagnosed 32 cases of umbilical vessel thrombosis in a series of 317 consecutive autopsies of spontaneous intrauterine fetal death selected from a file of 914 fetal and neonatal autopsies. All cases were singleton pregnancies without chromosomal abnormalities or structural malformations. Our data confirm the heterogeneous etiology and pathogenesis of umbilical vessel thrombosis and highlight a much higher incidence of this lesion than what has been previously reported. In addition, they point out the correlation between thrombosis of the umbilical vessels and specific histologic placental patterns that, in turn, might help explain the etiology and pathogenesis of thrombosis of the umbilical vessels. © 2010 Elsevier Inc. All rights reserved. 1. Introduction Thrombosis of the umbilical cord vessels (TUV) has been shown to be clearly associated with increased perinatal morbidity and mortality [1-4]. The presence of thrombi in fact has been linked with fetal organ infarcts [5], cerebral palsy [6,7], massive fetomaternal hemorrhage [8], and fetal growth restriction [9]. Heifetz [1], in his recognized milestone review, reports an incidence of umbilical cord thrombosis of 1:1300 deliveries of uncomplicated pregnancies and of 1:1000 perinatal autopsies, with a significant increase to 1:250 in high-risk pregnancies. On the other hand, Gilbert-Barness and Debich-Spicer [10] point out that any cord accidents, including those associated with excess length, brevity, or abnormal insertion, are responsible for 15% to 18% of late fetal death. Thrombi involving the umbilical cord are more frequently seen in the vein [11], whereas their location in both the vein and one or both arteries is much less frequent [1]. Even ⁎ Corresponding author. E-mail address: annamaria.marconi@unimi.it (A. M. Marconi). www.elsevier.com/locate/humpath 0046-8177/$ – see front matter © 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.humpath.2009.07.026 Human Pathology (2010) 41, 971–979