Thrombosis of the umbilical vessels revisited. An observational study of 317 consecutive autopsies at a single institution.

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.