Q- I just came back from my ultra sound and was told that I have a Velamentous Insertion. The Doctor said that they will monitor me and my baby for the rest of the pregnancy. Should I be worried? I have never heard of this before!
A-Velamentous Insertion
With velamentous insertion, the umbilical cord inserts into the chorion laeve at a point away from the placental edge, and the vessels pass to the placenta across the surface of the membranes between the amnion and the chorion.
One percent of singletons have velamentous insertion; however, this condition occurs in almost 15% of monochorionic twins and is common in triplets.
Velamentous insertion occurs (1) when placental tissue grows laterally, leaving the centrally located umbilical cord in an area that becomes atrophic, or (2) when the cord implants in the trophoblast anterior to the decidua capsularis rather than the trophoblast tissue that is destined to become the placental mass.
Velamentous insertion has been diagnosed by ultrasonography with a sensitivity of 67% and specificity of 100% in the second trimester; first trimester diagnosis is also possible14. The condition is associated with a lower maternal serum alpha-fetoprotein (AFP) and higher maternal serum human chorionic gonadotropin (hCG).
Velamentous insertion can cause hemorrhage if the vessels are torn when the membranes are ruptured, most often with a vasa previa (see below). Velamentous insertion of the cord is associated with low birth weight, prematurity, and abnormal fetal heart patterns in labor.
If detected, fetal growth may be monitored with ultrasonography in the third trimester. Consider an elective cesarean delivery to avoid a vasa previa rupture or fetal distress if the velamentous insertion is in the lower segment.
Marie Helen Beall, MD
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