Abstract

Emergency physicians are often the first providers to encounter patients with complications in early pregnancy. Point-of-care (POC) pelvic ultrasound is being increasingly used in the evaluation of emergency department (ED) patients with first trimester symptoms.[1] While the initial aim of POC ultrasound in this setting is to confirm an intrauterine pregnancy, a secondary goal is to differentiate between a normal and abnormal pregnancy. There exist a number of sonographic features to suggest a pregnancy is non-viable.[2–4] One of which is the entity known as the yolk stalk sign. During early embryonic development, the embryo is routinely detected immediately adjacent to the yolk sac, as the yolk stalk has yet to develop (Figure 1). Later in pregnancy, as the yolk stalk develops, the embryo will then be noted to separate from the yolk sac. "Yolk stalk sign" is abnormal separation of the embryo from the yolk sac in early embryonic development, specifically where crown-rump length (CRL) is 5 mm or less with no visible heartbeat.[5] At this point, any separation of the embryo from the yolk sac with development of yolk stalk is abnormal as the yolk stalk should be non-existent. Thus, an unexpected separation of the embryo from the yolk sac in embryos with a CRL of 5 mm or less and lacking a heartbeat could be indicative of a threatened abortion.[5]

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