Published online by Cambridge University Press: 05 July 2001
Ectopic pregnancy occurs when the conceptus implants outside the normal site within the uterine cavity. The most common site is within the Fallopian tube (98.3%), followed by abdominal (1.4%), ovarian (0.15%) and cervical (0.15%) implantation. Considering tubal ectopic pregnancies, 80% occur at the ampulla and 12% at the isthmus; 6% are fimbrial and 2% are interstitial. Approximately 5% to 5.7% of all clinical pregnancies from assisted reproductive technology (ART) in 1988–92 were ectopic; however, in 1995 the incidence was less at 2.8%. A meta-analysis of risk factors that predispose to ectopic pregnancy is depicted in Table 1. However, this meta-analysis does not control for the interplay of risk factors (multivariate analysis), including the impact of control group data and consequent problems of data collection (e.g. the incidence of pelvic inflammatory disease (PID) in the ectopic group is laparoscopically derived whereas it is derived from the history in the control group).