Prior Ectopic Pregnancy A previous history of ectopic pregnancy is a risk factor for another occurrence. The likelihood of recurrence exists because of the factors that led to an initial ectopic implantation and may be affected by the type of treatment the patient received with the first episode. There is concern that conservation of the tube at the time of removal of an ectopic pregnancy would increase the risk for recurrent ectopic pregnancy (27,48). The rates for intrauterine pregnancy (40%) and ectopic pregnancy (15%, range 4% to 28%) are similar after tubal removal or conservation (49). In a series of 54 patients with conservative surgical procedures for management of ectopic pregnancy, the incidence of future ectopic pregnancy could be predicted by the status of the contralateral tube: normal (7%), abnormal (18%), or absent (25%) (50). In a later study of pregnancy outcomes of 200 patients treated with tubal conservation for ectopic pregnancy, preservation of the tube did not increase the incidence of repeat ectopic pregnancy, but it did improve overall fertility rates (51). The risk of recurrence after methotrexate treatment is similar to that encountered with salpingectomy (52,53). The risk of recurrent ectopic pregnancy after two prior episodes may be as high as 30% (54).
Pelvic Infection The relationship of pelvic infection, tubal obstruction, and ectopic pregnancy is well documented. In a study of 2,500 women with suspected pelvic inﬂammatory disease (PID) who underwent diagnostic laparoscopy, the incidence of ectopic pregnancy in the subsequent pregnancy for those with laparoscopically confirmed disease was 9.1% compared with 1.4% in the women with normal laparoscopy (55). In a study of 415 women with laparoscopically proven PID, the incidence of tubal obstruction increased with successive episodes of PID: 13% after one episode, 35% after two, and 75% after three (56).
Chlamydia is an important pathogen causing tubal damage and subsequent tubal pregnancy. Chlamydia was cultured from 7% to 30% of patients with tubal pregnancy (57,58). A strong association between chlamydia infection and tubal pregnancy was shown with serologic tests for chlamydia (59–62). Conception is three times as likely to be tubal in women with anti– Chlamydia trachomatis titers higher than 1:64 than in those women whose titers were negative (63). The number of episodes of chlamydia is directly associated with risk for ectopic pregnancy. In a retrospective cohort study of 11,000 women, those with two chlamydial infections were more than twice as likely to develop ectopic pregnancy as those with one, and women with three or more were at greater than four times higher risk (64). Women at risk for chlamydia infections should be diligently tested, treated when infection is present, and counseled about the risk of ectopic pregnancy.