Differential Diagnosis for Ectopic Pregnancy vs Miscarriage

• Single most likely diagnosis:
  • Miscarriage: This is often the most common diagnosis in early pregnancy complications, given its higher incidence compared to ectopic pregnancy. Miscarriage, or spontaneous abortion, occurs when a pregnancy ends before the fetus can survive outside the uterus.
• Other Likely diagnoses:
  • Ectopic pregnancy: Although less common than miscarriage, ectopic pregnancy is a critical diagnosis to consider due to its potential for severe morbidity and mortality. It occurs when a fertilized egg implants outside the uterus, most commonly in a fallopian tube.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Ruptured ectopic pregnancy: This is a medical emergency. Early detection is crucial to prevent severe internal bleeding, which can be life-threatening.
  • Molar pregnancy: A rare condition where tissue that should form a fetus instead becomes an abnormal growth in the uterus. It can cause severe bleeding and other complications.
• Rare diagnoses:
  • Heterotopic pregnancy: A rare situation where there is both an intrauterine pregnancy and an ectopic pregnancy at the same time. This is more common in women undergoing fertility treatments.
  • Pseudosac or decidual cast: A condition that can mimic an ectopic pregnancy on ultrasound, where a collection of fluid or a cast of the uterine lining can be mistaken for an ectopic pregnancy or a miscarriage.