Causes of ectopic pregnancy

Ectopic pregnancy refers to pregnancy that occurs outside the uterine cavity, of which about 98% occurs in the fallopian tube. There are many causes of ectopic pregnancy, mainly:

(1) Women with chronic salpingitis. During the development of the fertilized egg, the fallopian tube transports the fertilized egg to the uterine cavity through the swaying of the cilia and the peristalsis of the smooth muscles of the fallopian tube. For women with chronic salpingitis, the inflammation causes adhesion of the fallopian tube, and in severe cases, it causes blockage, and the fertilized egg cannot reach the uterine cavity.

(2) Women with abnormal fallopian tube development. For example, lesions such as hypoplastic fallopian tube muscle layer and lack of cilia in the endometrium reduce the function of the fallopian tube in transporting fertilized eggs. Abnormal fallopian tube lesions also make it difficult for the fertilized egg to reach the uterine cavity smoothly.

(3) During the development of the fertilized egg, the fertilized egg may migrate out of the body and implant ectopically, resulting in an ectopic pregnancy.

(4) When suffering from diseases such as uterine fibroids and ovarian tumors, the fallopian tubes may be compressed or pulled, causing them to be displaced or deformed.

(5) Women with fallopian tube endometriosis. Endometriosis can narrow or block the tube lumen, making it difficult for the fertilized egg to pass through. Furthermore, when the fertilized egg comes into contact with the ectopic endometrium, the syncytial cells differentiate from the cytotrophoblast cells and secrete a mucosal dissolving protease, which erodes the ectopic endometrium to form a gap, allowing the fertilized egg to implant and develop, thus causing an ectopic pregnancy in the interstitial part of the fallopian tube.

(6) For women who have had fallopian tube surgery, whether it is natural or surgical recanalization, the fallopian tubes are no longer as smooth as before. The recanalized area is relatively narrow, and the fertilized egg is easily trapped and settled in the narrow area.

(7) Women who are currently using an intrauterine contraceptive device.