FIGURE 131.16 Standard transvaginal view of uterus In normal pregnancy, the earliest sonographic finding of an IUP is the gestational sac, which appears as a round fluid collection within the uterus ( Video 131.15 ) In transabdominal scanning, the gestational sac can be seen as early as to weeks’ gestational age Transvaginal scanning can reliably detect this finding about to 10 days earlier The yolk sac can be seen inside the gestational sac at approximately to weeks’ gestational age (5 to weeks by transvaginal scanning) and most authors consider this as definitive evidence of IUP A normal embryo will appear at the margin of the yolk sac at about 6.5 to 7.5 weeks’ gestational age and cardiac activity can be detected shortly thereafter ( Video 131.16 ) In the pregnant female, the standard for confirming an IUP on an emergency physician performed bedside ultrasound requires visualization of an intrauterine yolk sac, fetal pole, or intrauterine fetal heartbeat Visualizing only the gestational sac is not adequate as this can be the result of hormonal stimulation from an ectopic pregnancy When a fetal heartbeat can be seen, it should be documented with M-mode In an ectopic pregnancy, an adnexal mass or free fluid in the pelvis can sometimes be seen However, visualization of the ectopic pregnancy should not be the goal of the emergency physician Several protocols have been developed