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Diagnostic ultrasound ( PDFDrive )

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A

B

FIG. 32.7 Triplet Pregnancy Categorization. Each triplet needs amnionicity and chorionicity assigned accurately; analysis of more than one

characteristic might be needed. (A) Three separate placentas in a trichorionic triplet pregnancy at 13 weeks. There is a posterior placenta on the

left. The two anterior placentas appear merged, but a twin peak sign is present. See also Video 32.4. (B) Triplet pregnancy at 26 weeks’ gestational

age. There is both a thin (white arrowhead) and a thick (white arrows) membrane, consistent with triamniotic dichorionic twins.

A

B

C

D

FIG. 32.8 Velamentous Cord Insertion. Up to one-quarter of twin gestations have an abnormal placental cord insertion. (A) Straight separate

vessels are seen approaching the placenta in a 34-week twin. See also Video 32.5. (B) Same patient as A. Separate vessels (blue) can be seen

on the surface of the placenta with color Doppler. (C) Power Doppler image of a normal placental cord insertion in twin 1 of a monochorionic gestation

at 29 weeks’ gestational age. (D) Same patient as C. Power Doppler image of a velamentous placental cord insertion in twin 2.

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