What is a substantial separation of the placenta from uterus with no visible sign bleeding?

The term you are looking for is placental abruption. Placental abruption refers to the premature separation of the placenta from the inner wall of the uterus before delivery. This can cause significant bleeding, pain, and other complications. However, in some cases, placental abruption can occur without any visible signs of bleeding. This is known as a concealed placental abruption. Concealed placental abruption can be very dangerous, as it can lead to internal bleeding and other serious complications. It is important to seek medical attention immediately if you experience any signs or symptoms of placental abruption, even if there is no visible bleeding.