Ectopic pregnancies following female sterilization. A matched case-control analysis

The present study compared 15 ectopic pregnancies occurring after female sterilization (EPs) with 30 non-pregnant control patients who had also undergone female sterilization (NPCs) for a history of induced abortion, any pelvic surgery, abdominal surgery, or pelvic infection. EP cases and controls were individually matched for clinic, surgeon, surgical approach, tubal occlusion technique, and date of operation, as well as patients age and parity. The only significant difference was the greater proportion of EP patients, reporting a history of induced abortion (matched triplet odds ratio = 9.0, 95% confidence limits = 1.39, 58.26). Women with EPs were further compared with 78 women with post-sterilization intra-uterine pregnancies (unmatched). Results again show a significantly greater risk of conceiving an EP following previous induced abortion (odds ratio 5.8, 95% confidence limits = 1.78, 18.60). Women with previous abdominal surgery also ran a significantly higher risk of post-sterilization EP (odds ratio 10.0 95% confidence limits = 2.45, 40.83). Limitations of the data and clinical implications of the results are discussed.