PMC4900103_01
Grayscale sonographic findings at 11 + 1 weeks in a dichorionic, diamniotic twin pregnancy discordant for anencephaly that was incidentally diagnosed during an ER visit for vaginal bleeding (Case 1). Longitudinal image (top) through the head of normal twin "A" demonstrates a normal bony calvarium (arrowhead). In contrast, longitudinal image (bottom) through the head of twin "B" demonstrates absence of cranial structures above the level of the orbits (white arrow). No bony calvarium is visualized. These findings can be seen in acrania or anencephaly.
gr1a.jpg
PMC4900103_01_gr1a.jpg
fig1a
A appeared normal, with an average crown rump length (CRL) of 38 mm (estimated gestational age [EGA], 10+5 weeks). Anencephaly was suspected in twin B, based on the average CRL of 31 mm and nonvisualization of the calvarium, which in contrast was clearly visualized in twin A (Fig. 1A). At 18 + 0 weeks, anencephaly in twin B was confirmed by the absence of calvarium and brain tissue above the level of the orbits (Fig. 1).
PMC4900103_02
Grayscale sonographic findings at 11 + 1 weeks in a dichorionic, diamniotic twin pregnancy discordant for anencephaly that was incidentally diagnosed during an ER visit for vaginal bleeding (Case 1). Sonographic grayscale image of twin "B" (Case 1) at 18 + 0 weeks demonstrates absence of structures of the upper head above the level of the brainstem, with no upper skull or brain tissue present (between white arrows). Note the presence of normal cranial structures and brain on twin "A" (arrowheads).
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PMC4900103_02_gr1b.jpg
fig1b
The average CRL of twin B was 50 mm, corresponding to an EGA of 11 weeks 5 days (Fig. 2).