Endometrial Findings. In a woman in whom ectopic pregnancy is suspected, TVS is performed to look for findings indicative of uterine or ectopic pregnancy. During endometrial cavity evaluation, an intrauterine gestational sac is usually visible between 4Y2 and 5 weeks. The yolk sac appears between 5 and 6 weeks, and a fetal pole with cardiac activity is irst detected at 5Y2 to 6 weeks (Fig. 9-3, p. 159). With transabdominal sonography, these structures are visualized slightly later.
In contrast, with ectopic pregnancy, a trilaminar endometrial pattern can be diagnostic (Fig. 19-4). Its speciicity is 94 percent, but with a sensitivity of only 38 percent (Hammoud, 2005). In addition, Moschos and Twickler (2008b) determined sac within the endometrial cavity. Its cavity-conforming shape and central location are characteristic of these anechoic fluid col lections. Distal to this fluid, the endometrial stripe has a trilaminar pattern, which is a common finding with ectopic pregnancy.
(Reproduced with permission from Gala RB: Ectopic pregnancy. In
Hoffman BL, Schorge JO, Bradshaw KD, et al: Williams Gynecology, 3rd ed. New York, McGraw-Hili Education; 2016. Photo contributor:
Dr. Elysia Moschos.) in women with a pregnancy of unknown location at presenta tion that no normal IUPs had a stripe thickness <8 mm.
Anechoic luid collections, which might normally suggest an early intrauterine gestational sac, may also be seen with ectopic pregnancy. These include pseudogestational sac and decidual cyst. First, a pseudosac is a fluid collection between the endometrial layers and conforms to the cavity shape (see Fig. 19-4). If a pseudosac is noted, the risk of ectopic pregnancy is increased (Hill, 1990; Nyberg, 1987). Second, a decidual cyst is identiied as an anechoic area lying within the endometrium but remote from the canal and often at the endometrial-myometrial border. Ackerman and colleagues (1993 b) suggested that this finding represents early decidual breakdown and precedes decidual cast formation.
hese two indings contrast with the intradecidual sign seen with uterine pregnancies. With this, an early gestational sac is seen as an anechoic sac eccentrically located within one of the endometrial stripe layers (Dashefsky, 1988). The American College of Obstetricians and Gynecologists (2016) advises caution in diagnosing an IUP in the absence of a deinite yolk sac or embryo.
Adnexal Findings. he sonographic diagnosis of ectopic pregnancy rests on visualization of an adnexal mass separate from the ovary (Fig. 19-5). If fallopian tubes and ovaries are visualized and an extrauterine yolk sac, embryo, or fetus is identified, then an ectopic pregnancy is conirmed. In other cases, a hyperechoic halo or tubal ring surrounding an anechoic sac is seen (Nadim, 2017). Alternatively, an inhomogeneous adnexal mass is usually caused by hemorrhage within the ectopic sac. Overall, approximately 60 percent of ectopic pregnancies are seen as an inhomogeneous mass adjacent to the ovary; 20 percent appear as a hyperechoic ring; and 13 percent have an obvious gestational sac with a fetal pole (Condous, 2005). Importantly, not all adnexal masses represent an ectopic pregnancy, and integration of sonographic findings with other clinical information is necessary.
adnexal mass. In this last image, color Doppler shows a classic "ring