Vasa previa is a rare but serious pregnancy complication that can pose serious risks to the fetus if not carefully managed. It occurs when unprotected blood vessels from the umbilical cord travel across the opening of the cervix (or cervical os) . When the membranes around the fetus rupture, usually just before labor starts, the exposed blood vessels can burst, causing severe blood loss for the fetus or even death.

Vasa previa is usually diagnosed during ultrasound exams at around weeks 18 to 26. If there are ultrasound risk factors for vasa previa such as bilobed placenta or velamentous cord insertion, a transvaginal ultrasound can be done to see if there are blood vessels from the umbilical cord near the cervical os. If vasa previa is diagnosed before delivery, doctors usually do nonstress testing twice a week to check on the well-being of the fetus.

The treatment for vasa previa is a scheduled c-section delivery, which can prevent complications from occurring. If vasa previa is confirmed before labor, doctors will recommend that the baby is born by planned caesarean section at around 34–36 weeks of pregnancy. This means that the baby will be born prematurely, so a course of steroids may be given to help the baby’s lungs.