What is velamentous insertion of the umbilical cord?

Velamentous insertion of the umbilical cord is a condition where the fetal vessels (the umbilical arteries and veins) run alongside the membranes of the placenta rather than being covered by Wharton's jelly, which is a protective layer. This situation occurs when the umbilical cord inserts into the membranes rather than directly into the placental mass. The lack of Wharton's jelly puts the vessels at risk of being compressed or damaged, which can lead to various complications, including bleeding or even fetal distress if the vessels rupture.

In healthier attachments of the umbilical cord, such as those directly inserting into the placenta where Wharton's jelly surrounds the vessels, there is proper protection from trauma. Therefore, the answer conveys the key characteristic of velamentous insertion, underscoring that the vessels are not adequately protected, making it a significant point for clinical consideration in fetal monitoring.