An ectopic pregnancy occurs when the fertilized ovum is implanted in any tissue other than which location?

An ectopic pregnancy is defined as the implantation of a fertilized ovum in any location other than the normal uterine cavity. In this context, the correct answer is the uterine wall, as a normal pregnancy occurs when the fertilized ovum successfully implants within this structure.

When an ectopic pregnancy occurs, it may be situated in various typical abnormal locations such as the ovary (which would be classified as an ovarian pregnancy), or more commonly in the fallopian tube (tubal pregnancy), or even in the cervix. Each of these locations is abnormal for implantation and leads to the condition defined as ectopic pregnancy. Therefore, since the uterine wall is where implantation should occur in a normal pregnancy, it correctly identifies the one location that does not fall under the category of ectopic sites.