Altered innervation of the fallopian tube in ectopic pregnancy.

Three cases of ectopic pregnancy demonstrate different patterns of abnormal innervation in the fallopian tube. In the isthmus of the fallopian tube, we observed either (1) loss of nerves in one or more muscle layers of the fallopian tube or (2) large numbers of abnormal nerve profiles in one or more layers of muscle of the fallopian tube. Each woman had a prior history of one or more surgical terminations of pregnancy at indeterminate gestational ages. A proportion of uterine and tubal nerves pass through the uterosacral ligaments to reach the endometrial-myometrial nerve plexus and terminate as the innervation to the ipsilateral fallopian tube. We propose that injuries to the uterosacral ligaments by excessive traction to the cervix, or over-vigorous curettage to the endometrial-myometrial nerve plexus may account for these neuro-immunohistochemical findings. There were no signs of chronic infection or inflammation in the fallopian tube in any of these cases.