34-year-old gravida 1 para 0 presents with a complaint of abdominal pain

extrauterine gestational sac containing a yolk sac with or without an embryo

On transvaginal ultrasonography, the pathognomonic finding of an ectopic pregnancy is seen in 8%-26% of ectopic pregnancies. An extrauterine gestational sac containing a yolk sac with or without an embryo is the second most specific sign, but it may be confused with a hemorrhagic cyst containing debris that mimics a yolk sac or embryo. A tubal ring without an embryo or yolk sac has a specificity rate of 40%-68%, which is slightly higher than that of a complex or solid adnexal mass separate from the ovary. Complex pelvic fluid in the presence of a positive human chorionic gonadotropin level and no intrauterine pregnancy suggests ectopic pregnancy; however, it is not specific on its own. Finally, a decidual cyst may be found in either an ectopic or intrauterine pregnancy.

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Haury DE, Salhi BA. Acute complications of pregnancy. Marx JA, et al. Rosen's Emergency Medicine. 7th ed., 2009:2279-2297.

Lobo RA. Ectopic pregnancy. Lentz GM, et al. Comprehensive Gynecology. 6th ed., 2012:361-382.