<prompt> A 38-year-old pregnant woman is admitted to the emergency department with severe vaginal bleeding. Ultrasound examination confirms the initial diagnosis of placenta previa. What is the site of implantation in placenta previa?Uterine fallopian tubesCervixMesentery of the abdominal wallLower part of uterine body, overlapping the internal cervical os  <response>: By definition, the site of implantation in placenta previa overlaps the internal cervical os. Ectopic pregnancy in the uterine Fallopian tubes results in tubal pregnancy. The fundus of the uterus is the normal site of implantation. Implantation within the mesenteries of the abdomen will result in an abdominal pregnancy. The cervix is not a notable site of ectopic implantation. 