Greatest risk factor is a prior ectopic pregnancy, which carries a 17x higher risk.
Patients with histories of PID and cigarette smoking present educational opportunities.
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Rana, P; Kazmi, I; Singh, R; Afzal, M; Al-Abbasi, FA; Aseeri, A; Singh, R; Khan, R; Anwar, F (2013). "Ectopic pregnancy: a review".Archives of Gynecology and Obstetrics. 288 (4): 747–57. doi: 10.1007/s00404-013-2929-2.