Ectopic Pregnancy

An ectopic pregnancy implants outside the uterine cavity, most often in the ampulla of a fallopian tube. The danger is not simply that implantation is in the wrong location: a tube cannot expand safely with a growing gestation, and trophoblastic invasion can erode vessels until rupture causes intraperitoneal hemorrhage. The first clinical decision is therefore whether the patient is stable and whether rupture or significant bleeding is possible—not which medication to choose. A positive pregnancy test without a confirmed intrauterine pregnancy is a pregnancy of unknown location, not yet a diagnosis of ectopic pregnancy. Begin with pregnancy confirmation and transvaginal ultrasonography. If the scan is nondiagnostic, serial transvaginal ultrasound and/or quantitative serum hCG are needed; a single hCG value cannot safely settle the pregnancy's location. SOGC guidance supports a validated model such as M6 to identify patients who need closer follow-up. Once rupture is excluded and the location and risk profile are clarified, treatment is matched to the clinical picture: methotrexate for selected stable, unruptured ectopic pregnancies; surgery when rupture, instability, contraindication, or treatment failure changes priority; and expectant management...