Three-dimensional HDlive rendering images of the TRAP sequence in the first trimester: reverse end-diastolic umbilical artery velocity in a pump twin with an adverse pregnancy outcome.

Abstract

The twin reversed arterial perfusion (TRAP) sequence, also known as fetus acardius, occurs in 0.3 % of monozygotic twin gestations, which amounts to a frequency of about 1 per 35,000 deliveries [1, 2]. There have been only two reports on antenatal three-dimensional (3D) sonographic diagnosis of the TRAP sequence during pregnancy [3, 4]. The HDlive is a new surface render mode involving the use of skin-like colors, and ‘‘its system uses an adjustable light source, giving the operator the opportunity to create lighting and shadowing effects and thereby increasing depth perception’’ [5]. There have been four reports on fetal, placental, and umbilical cord ultrasound images using the 3D HDlive rendering mode [5–8]. Employing 3D HDlive with new skin-like colors, we can achieve a natural and anatomically realistic appearance of the embryo and fetus in utero. However, there has been no reports on 3D HDlive rendering displays of the TRAP sequence in the first trimester of pregnancy. There have been five reports on reverse end-diastolic velocity in umbilical artery velocimetry with an adverse pregnancy outcome at less than 14 weeks of gestation, which suggested that reverse end-diastolic umbilical artery velocity waveforms might be an ominous sign in early pregnancy [9–13]. However, there are no sonographic findings in the first trimester that can help to distinguish between pregnancies resulting in death of the pump twin from those that will survive until prophylactic intervention at 16–18 weeks in TRAP sequence cases [14]. In this report, we present our experience of a TRAP sequence reconstructed employing the 3D HDlive rendering mode, and discuss the reverse end-diastolic blood flow velocity waveform in the umbilical artery of a pump twin with an adverse pregnancy outcome in the first trimester. A 33-year-old pregnant Japanese woman, gravida 1, para 0, was referred to our ultrasound clinic because of a suspected TRAP sequence at 11 weeks and 6 days of gestation. The 2D sonography and the 3D surface rendering mode (Voluson E8, GE Healthcare, Milwaukee, WI, USA) showed a normal pump twin and small acardiac twin with acrania and absence of the heart and upper limbs (Fig. 1). The crown-rump length of the pump twin was 43.3 mm (consistent with the corresponding age), and no gross fetal anomaly was noted. The longitudinal distance between the upper pole and rump of the acardiac fetus was 27.6 mm. The 3D HDlive rendering mode provided anatomically realistic images for TRAP sequence diagnosis (Fig. 2). Color and pulsed Doppler sonography revealed a reverse end-diastolic umbilical artery velocity in the pump twin at 13 weeks and 1 day of gestation (Fig. 3a). There was a single-artery umbilical cord between the placenta and acardiac fetus, and a reversed tiny absent diastolic umbilical artery velocity was noted (Fig. 3b). Fetal demise of the pump twin was confirmed at 14 weeks’ gestation. Delivery C. Tenkumo H. Tanaka M. Ito E. Uketa N. Mori U. Hanaoka K. Kanenishi T. Hata (&) Department of Perinatology and Gynecology, Kagawa University School of Medicine, 1750-1 Ikenobe, Miki, Kagawa 761-0793, Japan e-mail: toshi28@med.kagawa-u.ac.jp