Venous/placental lake

Has anyone had a venous/placental lake show up on their anatomy scan? How did everything go? My doctor doesn't seem worried and doesn't want me to worry, but it was still news I didn't want to hear. I go back in for another ultrasound on January 18th. Please share your experiences with this if you have had this! He said its small, but somewhat close to the umbilical cord. He wants to just recheck in 4 weeks to make sure it didn't grow to block the blood flow in the cord.