The contralateral corpus luteum and tubal pregnancy.

One hundred fourteen cases of tubal pregnancy were examined for evidence of active or chronic salpingitis, other anatomic and functional etiologies, and the side of the corpus luteum relative to the pregnancy. A corpus luteum was found ipsilateral to the tubal pregnancy in 80 cases (70%) and contralateral in 18 (16%). In 16 cases (14%), the position of the corpus luteum could not be identified by inspection. No differences were noted among the groups in days from last normal menstrual period or the incidence of irregular bleeding. Of the 98 cases in which a corpus luteum was identified, 53 women (54%) had at least one condition that could be considered etiologic for tubal pregnancy, including 38 (39%) who had microscopic evidence of chronic salpingitis. No association was found between the laterality of the corpus luteum and the presence of risk factors, including mechanical factors. Possible explanations for absent corpora lutea in association with tubal pregnancies are discussed.