How many centimeters is the placenta from the internal cervical os to be diagnosed as placenta previa?

Patient's question:

No

Doctor's answer:

The placenta is located in the lower segment of the uterus. When the edge of the placenta is very close to but does not reach the internal cervical os, it is referred to as a low-lying placenta. Generally, if the distance from the placental edge to the internal cervical os is less than 3 cm, it is considered a low-lying placenta.