The exact cause of ectopic pregnancy remains unclear, but the primary contributing factor is likely fallopian tube abnormalities.
Patients with a history of chronic salpingitis, appendicitis, pelvic tuberculosis, peritonitis, or endometriosis may develop fallopian tube adhesions, narrowing, or partial blockages, leading to ectopic pregnancy.Additionally, underdeveloped fallopian tubes can disrupt the normal movement of the fertilized egg. Congenital abnormalities such as tubal diverticula or accessory fimbriæ may also contribute to ectopic pregnancy.
If tubal abnormalities are not the cause, ectopic pregnancy may result from a wandering fertilized egg. After fertilization in one fallopian tube, the fertilized egg may travel through the uterine cavity into the opposite tube, implant there, or wander within the abdominal cavity. Prolonged migration allows the fertilized egg to grow larger, potentially leading to tubal pregnancy. Contraceptive failure is another cause of ectopic pregnancy.
Many women now use intrauterine devices (IUDs) for contraception, commonly known as "getting an IUD." However, if contraception fails with an IUD, the risk of ectopic pregnancy increases.Additionally, certain contraceptive pills with lower progestin doses may cause abnormal tubal contractions, leading to ectopic pregnancy. Women who become pregnant after emergency contraception failure—which often contains high doses of estrogen—also face an increased risk of tubal pregnancy.