QOD

Which of the following findings on transvaginal ultrasound is the first non-controversial and definitive sign in the initial diagnosis of an intrauterine pregnancy?
A. double decidual sign
B. intradecidual sign
C. pseudogestational sac
D. ring signE. yolk sac in the uterus


A double decidual sign is one of the first signs that is seen in an IUP and should be visualized 5 weeks after the last menstrual period. The double decidual sign is described as two echogenic rings surrounded by intrauterine fluid collection. (See Figure 1.) Caution should be taken, however, to differentiate this from a pseudogestational sac, which can be seen in ectopic pregnancy. This pseudogestational sac (see Figure 2) is due to a small amount of fluid being trapped within the endometrial canal, mimicking the appearance of the double decidual sign. Because of the risk of potential misinterpretation, there is controversy about using the double decidual sign to rule in an IUP.
The intradecidual sign is a linear echo in the uterine cavity in a pregnancy < 9 weeks in conjunction with a gestational sac or an echogenic area of early implantation located within a markedly thickened uterine cavity. (See Figure 3.) These findings may be mistaken for a decidual cyst or an endometrial cyst, which may coexist with ectopic pregnancy and makes the intradecidual sign controversial as a reliable finding for an IUP.
By 5.5 weeks from the last menstrual period, a yolk sac should be visualized within the gestational sac. (See Figure 4.) This is the earliest definitive sign of an intrauterine pregnancy. Gestations longer than 5.5 weeks have a visible IUP seen nearly 100% of the time. Operator expertise, however, decreases the sensitivity of TVU to 73-93%. If a definite IUP is seen and the patient is not at risk for heterotopic pregnancy (ectopic pregnancy and IUP), the patient does not have an ectopic pregnancy.
Diagnostic criteria for a tubal ectopic pregnancy on TVU include an empty endometrial cavity with either a heterogeneous adnexal mass (seen in approximately 60% of cases), an extra-uterine gestation sac with a yolk sac that may have a fetal pole +/- cardiac activity (seen in 13% of cases), or a ring sign. A ring sign is a mass in the adnexa with a hyperechoic ring around the gestational sac seen on TVU in approximately 20% of cases. (See Figure 5.) Diagnostic criteria for interstitial/cornual ectopic pregnancy include an empty endometrial cavity with a pregnancy visualized outside of the endometrial echo and surrounded by myometrium within the interstitial region.
Studies have shown that the overall sensitivity of TVU (TransVaginalUltrasound) for diagnosing ectopic pregnancy ranges between 74% and 98% and has a specificity of 99.9%. Patients with PUL on an initial TVU may in fact have an ectopic and should be followed closely.
In the event of rupture of the ectopic pregnancy, free fluid may be seen on TVU as an anechoic area around the uterus, in the pelvis or Morrison's pouch. (See Figure 6.)
Answer: E