Tubal Surgery As would be expected, factors that disrupt normal tubal anatomy are the primary etiology for ectopic pregnancy. Women with prior tubal surgery have a more than 20-fold increased risk of subsequent ectopic pregnancy (32). Tubal repair or reconstruction may be performed to correct an obstruction, lyse adhesions, or evacuate an unruptured ectopic pregnancy. Although it is clear that tubal surgery is associated with an increased risk for ectopic pregnancy, it is unclear whether the increased risk results from the surgical procedure or from the underlying problem. A four-to fivefold increased risk is associated with salpingostomy, neosalpingostomy, fimbroplasty, anastomosis, and lysis of complex peritubal and periovarian adhesions (38). After tubal surgery, the overall rate of ectopic pregnancy is 2% to 7%, and the viable intrauterine pregnancy rate is 50% (38).
Though tubal sterilization remains one of the most effective forms of contraception, failures do occur; when they do, they are more likely to result in ectopic gestation. The 10-year cumulative incidence of pregnancy after any form of tubal sterilization is 18.5 per 1,000 woman-years and the likelihood of sterilization failure does not decrease with time since the procedure (39). Despite a greater proportion of poststerilization failures resulting in ectopic pregnancy, the absolute rate of ectopic pregnancy is decreased after sterilization (40). Calculating cumulative lifetime risk for ectopic pregnancy according to method of contraception, sterilized women have a lower cumulative risk for ectopic pregnancy than IUD users or nonusers of contraception, and women using barrier methods or oral contraceptives have the lowest risk (40).
The 10-year cumulative incidence of tubal pregnancy after any sterilization procedure is 7.3 per 1,000 procedures (41). The risk depends on the sterilization technique and the woman’s age at the time of sterilization: postpartum partial salpingectomy and unipolar coagulation have the lowest rates of ectopic pregnancy (1.5 and 1.8 per 1,000 procedures), while bipolar coagulation techniques had the highest incidence (17.1 per 1,000 procedures). Spring clip and band application techniques have 10-year ectopic rates similar to the general incidence, 8.5 and 7.3 per 1,000 procedures, respectively (41). Women younger than 28 years at the time of sterilization are more likely to have a failure than women over 34 years.
Sterilization reversal increases risk for ectopic pregnancy. The exact risk depends on the method of sterilization, site of tubal occlusion, residual tube length, coexisting disease, and surgical technique. In general, the risk for reanastomosis of a cauterized tube is up to 17%, and it ranges from 6% to 9% for reversal of Pomeroy and 5% to 11% for reversal of ring procedures (42–47).