Magnetic resonance imaging in tubal and non-tubal ectopic pregnancy

Ectopic pregnancy is the leading cause of pregnancy-related death in the first trimester. Ectopic pregnancy is usually diagnosed by clinical, laboratory, and sonographic findings, with implantation most commonly located in the ampullary part of the fallopian tube. However, pregnancies that develop at unusual implantation sites, such as angular, interstitial, cornual, cervical, ovarian, cesarean scar, and abdominal cavity pregnancies, may rarely occur. Although ultrasound is considered the primary pregnancy-related imaging modality, it may not be able to illustrate the implantation site in certain types of pregnancy. Magnetic resonance imaging (MRI) has gained popularity as an imaging tool for evaluating pregnant patients, and it is used as a problem-solving tool in special circumstances, including ectopic pregnancy. MRI can confirm abnormal implantation site, and distinguish rupture from nonrupture cases before management. Other benefits include absence of ionizing radiation, superb soft tissue contrast, and sensitivity sufficient for identifying hemorrhage and its stages. This article summarizes imaging findings in tubal and non-tubal ectopic pregnancy with an emphasis on the roles and protocols of MRI, key MRI features, and differential diagnosis.