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| Velamentous Insertion of Umbilical Cord |
| Etiology • Unknown |
| Pathogenesis • Two theories of pathogenesis: • (1)Abnormal implantation with embryo facing away from endometrium so that vessels have to reach chorionic plate through membrane • (2) Trophotropism where placenta has "wandered" by atrophying on one side and proliferating on the other (away from cervix and placenta previa to fundus) with the result that the cord may be left in the membranes • Neither theory proven, |
| Epidemiology • 1% of singleton pregnancies • Associated with twinning • Associated with single umbilical artery |
| General Gross Description • Umbilical cord inserts into the membranes such that large vessels must travel unsupported in the membranes • May see thrombosis or laceration in cases with poor pregnancy outcome |
| General Microscopic Description • Sections of the membranes show large vessels resembling those seen in the chorionic plate coursing through the membranes |
| Clinical Correlation • Vulnerable to vasa previa (membranous vessels preceding the baby at delivery) • Thrombosis or laceration may occur and be associated with sudden death at late term or rapid fetal exsanguination at delivery |
| References • Benirschke K, Kaufmann P. Pathology of the human placenta, 3rd ed. New York: Springer-Verlag, 1995, pp. 338-342. |
| Velamentous Insertion of Umbilical Cord |
| Synopsis by: Melinda Sanders M.D. (T88800M29650)[424] |
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