PMC6029288_01
Transvaginal sonography at 6 weeks of gestation with cesarean scar pregnancy. The myometrial border and bladder lining remain smooth.
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F1
At the first trimester, transvaginal ultrasonography was performed at 6 weeks of gestation, which revealed an intrauterine gestational sac (Figure 1).
Transabdominal sonography at 15 weeks of gestation. (A) Breech presentation and placenta previa are seen. (B) Placenta previa totalis is shown with irregular contour of placenta and myometrium. Thin myometrium is indicated by arrows. (C) Multiple vascular sinuses formed in the placenta and are indicated by arrows. (D) Notice that whole layer penetration of myometrium is seen with interrupted myometrial lining (red arrows). (E) Interrupted retroplacental hypoechoic zone is indicated by arrows (red arrow). (F) Doppler scan shows abnormal vascularity beneath and inside the placenta.
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F2
At the second trimester, transabdominal ultrasonography was performed at the 15th week of gestation, and placenta previa totalis was found with whole internal os covered by the placenta (Figure 2A). Loss of homogeneous appearance, protruding placental base into the myometrium, thinning of the retroplacental myometrium, and interrupted retroplacental anechoic band were noted with multiple lucent vascular lake intraplacentally, which were compatible with placenta accreta (Figures 2B-2E). Color Doppler also showed chaotic vascularity inside and beneath the placenta (Figure 2F).
Transabdominal sonography at 32 weeks of gestation. (A) Enlarged placental size and multiple vascular lakes are seen, which are called "lacunar sign." Uterovesicle border is not seen clearly in this picture (red arrows). (B) Doppler scan shows tortured and irregular vessels in placenta, which formed some vascular sinuses with turbulent flow.
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F3
Persistent placenta previa totalis was confirmed, and increased heterogeneity with abnormal vasculature was seen in the placenta (Figure 3A). There was obvious progression in number and size of vascular sinus, and color Doppler indicated increased turbulent flow as well (Figure 3B). The uterovesicle border was not seen so clearly during the sonography examination (Figure 3A).