The etiology of ectopic pregnancy.

The cause of ectopic pregnancy is associated with two major categories: the integrity of the oviduct and the quality of the fertilized ovum. Several conditions that alter the tubal transport system include inflammatory insults, intrauterine devices, surgical manipulation, tubal ligations, salpingitis isthmica nodusa, DES exposure, and induced abortions. Risk factors that may theoretically alter ovum quality or the hormonal environment include ovulation induction, fertilization in vitro, delayed ovulation, and transperitoneal ovum migration. As we continue to investigate the fallopian tube and the fertilized ovum as unique entities, our knowledge will increase about the cause of ectopic gestations.