and Marcelo Zugaib4
(1)
São Paulo University, Bauru, Brazil
(2)
Parisian University, Bauru, France
(3)
Member of International Fetal Medicine and Surgery Society, Bauru, Brazil
(4)
Obstetrics, University of São Paulo, Bauru, Brazil
16.1 Introduction
Twin pregnancy is associated with high neonatal morbidity and mortality rates resulting in a high incidence of prenatal complications (maternal and fetal) and preterm labor. Within this context, ultrasound plays a key role in the prenatal diagnosis of common pathological conditions in multiple pregnancies, such as intrauterine growth retardation (IUGR), fetal malformations, and twin-to-twin transfusion syndrome (TTTS).
Fig. 16.1
Cross-section of the uterine cavity showing two gestational sacs at 4.5 weeks, with their trophoblastic crowns (arrows)
Fig. 16.2
Cross-section of the uterine cavity showing two gestational sacs at 5.5 weeks (arrows)
Fig. 16.3
Cross-section of the uterine cavity showing two gestational sacs (T1 and T2) separated by a thick layer of trophoblast forming the lambda sign (arrows), confirmation of a dichorionic pregnancy
Fig. 16.4
Cross-section of gestational sacs (SG) separated by a thick layer of trophoblast forming the lambda sign (arrows)
Fig. 16.5
Thick chorioamniotic separation (arrows) between the two embryos demonstrating, in addition to the presence of the lambda sign, that this is a dichorionic–diamniotic pregnancy
Fig. 16.6
Cross-section of two gestational sacs showing the lambda sign (arrows)
Fig. 16.7
Cross-section of the uterine cavity showing three gestational sacs, indicating a triplet pregnancy
Fig. 16.8
Coronal section of the uterine cavity showing four gestational sacs (1, 2, 3, and 4)
Fig. 16.9
Same case as in Fig. 16.8, where the oblique view shows the presence of the fifth gestational sac (1, 2, 3, 4, and 5)
Fig. 16.10
Twin pregnancy with an interrupted twin. On the right, embryo with crown–rump length = 28.6 mm and on the left biparietal diameter of the other twin, already measuring 38 mm. CP = cephalic pole of non-evolving embryo, T = non-evolutive embryo tail, arrows = head circumference of twin in evolution
Fig. 16.11
Twin pregnancy with non-evolving twins. On the right, the arrows show an irregular pole and small head. Note, on the left, the head circumference of the evolving twin (arrows)
Fig. 16.12
Longitudinal section of the uterus that shows a portion of the placenta with suggestive heterogeneous echotexture, suggesting partial hydatidiform mole. A mole with embryo or twin pregnancy with molar degeneration of one of the fetuses
Fig. 16.13
The same view as in Fig. 16.12, but with greater magnification showing a difference in echotexture from normal placenta and the molar degeneration, which is more heterogeneous and cystic (arrows)
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