Light and electron microscope examination of the effects of methotrexate on the endosalpinx

In view of these findings, we conclude that the ultrastructural derangements resulting from administration of Mtx in doses in excess of 1 mg/kg can cause a reduction in the surface epithelium's ability to make rhythmic lashing movements and can impair the patency of the fallopian tubes. All these disturbances could be involved to some degree in the causation of infertility and recurrent ectopic pregnancy. Therefore, the dosage of Mtx should be limited to use of the lowest effective dose to avoid these adverse effects.