Final answer:
An ectopic pregnancy occurs when an embryo implants outside the uterus, with the most common site being the fallopian tubes; it requires medical or surgical intervention.
Step-by-step explanation:
A ectopic pregnancy is a condition where the embryo implants and grows outside the uterus, most commonly in a fallopian tube which is known as a tubal pregnancy. Other ectopic pregnancy locations can include the abdominal cavity, ovary, or cervix, places where the embryo cannot properly develop. In a tubal pregnancy, scar tissue from an infection can block or snag the embryo, preventing it from reaching the uterus.
Medical treatment or surgical intervention is often required for ectopic pregnancies. Administration of methotrexate, a cytotoxic drug, can stop embryo development if the ectopic pregnancy is detected early. However, if the fallopian tube ruptures, emergency surgery is necessary.