Pregnancy of Unknown Location, Early Pregnancy Loss, Ectopic Pregnancy, and Cesarean Scar Pregnancy

Pregnancy is an inefficient process. A large proportion of early pregnancies end in miscarriage or early pregnancy failure. Ectopic pregnancies, those located outside of the proper uterine location, cause significant maternal morbidity and mortality. This chapter will review the utility of ultrasound in early pregnancy, when its use is essential in the differentiation of normal and abnormal gestation. The evaluation of pregnancy of unknown location, early pregnancy loss/failure, ectopic pregnancy, and cesarean scar pregnancy is reviewed. The ultrasound findings of normal and abnormal pregnancies are described. The synthesis of clinical, laboratory, and imaging findings is described. Emphasis is placed on accurate diagnosis without overdiagnosis, which can place normal pregnancy at risk.