Pictorial essay Med Ultrason 2015, Vol. 17, no. 4, 545-549DOI: 10.11152/mu.2013.2066.174.pdg

AbstractThe authors present their experience in prenatal diagnosis of placental and umbilical cord pathologies, using three-dimen-

sional ultrasound (3DUS) in the rendering and tomography ultrasound imaging (TUI) modes, associated with color Doppler in some cases. Cases of placenta accreta/placenta previa, circumvallate placenta, succenturiate lobe, true knot of the umbilical cord, nuchal cord, and marginal/velamentous umbilical cord insertion are presented. 3DUS can contribute to improve the ac-curacy of prenatal diagnosis of placenta and umbilical cord pathologies.

Keywords: prenatal diagnosis, placenta, umbilical cord, Doppler ultrasonography, 3D ultrasound.

Prenatal diagnosis of placenta and umbilical cord pathologies by three-dimensional ultrasound: pictorial essay.

Guilherme de Castro Rezende1, Edward Araujo Júnior2

1Department of Obstetrics and Gynecology, Center of Fetal Medicine, Federal University of Minas Gerais (UFMG), Belo Horizonte-MG, 2Department of Obstetrics, Paulista School of Medicine-Federal University of São Paulo (EPM-UNIFESP), São Paulo-SP, Brazil.

Received 22.03.2015 Accepted 21.04.2015 Med Ultrason 2015, Vol. 17, No 4, 545-549 Corresponding author: Prof. Edward ARAUJO JÚNIOR, PhD Department of Obstetrics, Paulista School of Medicine-Federal University of São Paulo (EPM-UNIFESP) Rua Belchior de Azevedo, 156, apto. 111 Torre Vitoria, São Paulo–SP, Brazil CEP 05089-030 Phone/Fax: +55-11-37965944 E-mail: araujojred@terra.com.br

Introduction

Ultrasound professionals often underestimate the value of ultrasonographic evaluations of the placenta and umbilical cord. Placenta and umbilical cord abnormali-ties may have important prognostic implications for peri-natal morbidity and mortality. In recent years, with the advancement of high-resolution ultrasound, the three-di-mensional ultrasound (3DUS), associated in some cases with color and/or power Doppler, has become an impor-tant prenatal diagnostic tool [1-3].

This pictorial essay presents the authors’ experience while using 3DUS (associated in some cases with color and/or power Doppler) in the diagnosis of placenta and umbilical cord pathologies.

Placenta accreta

Placenta accreta (defined as an abnormal adherence of the placenta to the uterus, rendering the separation from the uterus difficult or impossible) is a rare complication, with an estimated prevalence of 1 in 2,500 pregnancies. Nonetheless, it has become an important etiology of ma-ternal morbidity and mortality, as it is the leading cause of emergency peripartum hysterectomy [1,4]. Clinically, the main feature of placenta accreta is abundant utero-placental neovascularization, which can cause severe and difficult-to-treat bleeding [1,5]. The prevalence of placenta accreta has been increasing, and the most com-mon predisposing conditions are prior cesarean section and placenta previa [1,6].

A prenatal diagnosis of placenta accreta is essential for proper delivery preparation and, usually, for the per-formance of a cesarean hysterectomy [1,6]. The ultra-sound diagnosis is based on gray-scale findings, which can be associated with color Doppler and 3DUS. Among these findings, irregularly shaped placental lacunae, thin-ning of the myometrium, in which the placenta is im-planted, and loss of retroplacental hypoechoic area are notable [1,5]. In figure 1 are shown some examples of this pathology.

546 Guilherme de Castro Rezende et al Prenatal diagnosis of placenta and umbilical cord pathologies

Circumvallate placenta

Circumvallate placenta is an abnormality in the shape of the placenta in which the membranes are in-serted from the inside towards the edge and through the center of the placenta. It is characterized by cy-lindrical, peripherally thickened chorioamniotic mem-

branes [2,7]. The incidence of circumvallate placenta varies from 0.5% to 18% in postpartum placental ex-aminations [2]. This placental form is associated with an increased risk of several perinatal complications, particularly amniotic rupture, intrauterine growth re-striction, abruptio placentae, fetal malformation, and perinatal death [2].

Fig 1. a) Longitudinal plane of the three-dimensional (3D) image with HD flow of the cervix and anterior lower uterine segment, using tomography ultrasound imaging (TUI) software, evidencing loss of placental hypoechoic area (white arrows) in a case of pla-centa accrete in the third-trimester of pregnancy; b) cervix and anterior lower uterine segment using TUI software, showing loss of placental hypoechoic area; c) cervix and anterior lower uterine segment using TUI software, evidencing loss of placental hypoechoic area; d) photograph of the same uterus after a cesarean hysterectomy and after longitudinal incision, showing placental invasion into the myometrium at the segment region (black arrows); e) longitudinal and transverse planes of the 3D image of the cervix and ante-rior lower uterine segment using TUI software, showing the placenta bypassing the internal opening of the cervix, and the presence of placental hypoechoic area (white arrows), placenta previa. BEX: bladder; PLAC: placenta; COLO: cervix.

Fig 2. a) Two-dimensional image of a transverse plane of the placenta, showing thick peripheral edges and corners, circumvallate placenta (white arrows), in a third-trimester pregnancy; b) Three-dimensional image with the HD live software of a circumvallate placenta, showing thick peripheral edges and curves (white arrow) in a pregnancy in the third trimester, with light incidence at 1 o’clock; c) Three-dimensional image with HD live software of a circumvallate placenta, evidencing thick peripheral edges and curves (white arrow), appearance of a tire mounted on a wheel, with light incidence at 1 o’clock, in a third-trimester pregnancy.

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Two-dimensional ultrasonographic findings are de-scribed as a placental band or placental shelf, specifically the thick, cylindrical placental edge [2] (fig 2). Nonethe-less, the prenatal diagnosis of circumvallate placenta is rare [2]. Figures 2B and 2C illustrate, through 3DUS

with HD live software, a finding described as the “tire” sign, in which a circular depression with a thick periph-eral ring on the chorionic plate is observed, resembling a tire mounted on a wheel [2].

Succenturiate lobe

Succenturiate lobe or accessory lobe is recognized by ultrasonography as a mass of placental tissue separated from the main lobe, occurring in approximately 5% of pregnancies [7] (fig 3). This finding is correlated with a higher incidence of velamentous umbilical cord inser-tion, vasa previa, and placental infarction [8].

Marginal/velamentous umbilical cord insertion

The insertion of the umbilical cord at the edge of the placenta, known as battledore placenta, occurs in 7% of pregnancies [7]. In 1% of all pregnancies, the umbilical cord falls beyond the placental edge, allowing a variable portion of the umbilical cord to remain between the two

Fig 3. a) Three-dimensional image with HD live software of a circumvallate placenta, evidencing thick peripheral edges and curves (white arrows) and the appearance of a tire mounted on a wheel, with light incidence at 1 o’clock, in a third-trimester pregnancy; b) Three-dimensional image with HD live software, evidencing both main and accessory lobes (white arrows) with central light incidence, in a third-trimester pregnancy.

Fig 4. a) Three-dimensional image with HD live software, showing a marginal insertion of the umbilical cord (white arrows), with light incidence at 9 o’clock, in a third-trimester pregnancy; b) Transverse and longitudinal planes of the three-dimensional image with HD flow of the placental margin, using tomography ultrasound imaging (TUI) software, evidencing the insertion of the cord, in a third-trimester pregnancy; c) Longitudinal plane of two-dimensional image with color Doppler of the velamentous umbilical cord insertion, in a third-trimester pregnancy; d) Postpartum placenta photography, confirming the diagnosis of velamentous umbilical cord insertion (white arrow).

Fig 5. a) Two-dimensional image with power Doppler of a longitudinal plane of the umbilical cord, suggesting a true knot of the umbilical cord (white arrow) in a third-trimester pregnancy; b) Three-dimensional image with power Doppler of a longitudinal plane of the umbilical cord, suggesting a true knot of the umbilical cord (white arrow) in a third-trimester pregnancy; c) Postnatal umbilical cord photography, confirming the diagnosis of true knot of the umbilical cord (white arrow); d) Three-dimensional image with HD flow of a false knot of the umbilical cord, in a third-trimester pregnancy.

548 Guilherme de Castro Rezende et al Prenatal diagnosis of placenta and umbilical cord pathologies

membranes without the protection of the Wharton’s jelly [7,9]. This condition is associated with fetal growth re-striction, congenital anomalies, retained placenta, and prematurity, in addition to rupture, thrombosis of the umbilical vessels, and fetal death [7,9]. The ultrasound diagnosis is possible; placental cord insertion should be routinely tracked at obstetric ultrasound [7,9] (fig 4).

True knot of the umbilical cord

A true knot of the umbilical cord is observed in ap-proximately 0.3%–2.1% of births [10]. Although it is a rare event, this finding is associated with serious con-sequences. Fetal mortality rate can be four to ten times higher when compared with that of the general obstetric population [3]. It can also be associated with a non-reas-suring fetal heart rate pattern during labor and higher inci-dence of cesarean section [10]. Some obstetric factors are described to be correlated with true knot of the umbilical cord: polyhydramnios, gestational diabetes, fetuses that are small for gestational age, long umbilical cord, male fetus, and genetic amniocentesis [10]. Prenatal diagnosis of true knot of the umbilical cord became possible with the modernization of ultrasound equipment; however, it is still an uncommon diagnosis [3,10]. Ultrasound with gray scale, color Doppler, two- and three-dimensional power Doppler, and 3DUS with HD flow software are used in the diagnosis of this condition, which is suspect-ed by the visualization of a “loop” (fig 5).

Nuchal cord

Nuchal cord is defined as a 360° turn of the umbili-cal cord around the fetal neck [11]. The prevalence of nuchal cord at delivery has been reported to be between 6% and 37% [11]. The prevalence of single, double, tri-

ple, and quadruple nuchal cord was described by Shui et al to be of 10.6%, 2.5%, 0.5%, and 0.1%, respectively [12]. There is a linear increase in the prevalence of single or multiple nuchal cords with advancing gestational age [11,12]. Prenatal diagnosis of nuchal cord is not routinely done, but there is a correlation between this event and abnormal fetal heart rate pattern during labor [11]. The sagittal and transverse planes at the fetal neck level allow for a precise diagnosis [12], and the sensitivity of diag-nosis usually improves with the use of color Doppler and 3DUS [11,12] (fig 6).

Conclusions

With technological advancement, new possibilities in diagnostic imaging are made available for the antenatal period [13]. 3DUS has been used as a complementary technique for prenatal diagnosis of placenta and um-bilical cord pathologies [1-3]. Some of these conditions, which are associated with high perinatal morbidity and mortality, have a low antenatal detection rate as they are often diagnosed at birth or postpartum [1,3,6]. Prenatal diagnosis of these pathologies allows for the quantifica-tion of risks, prenatal and delivery programming, and guidance to families, having a significant impact on the follow-up of these patients. 3DUS also allows for data storage, which can be forwarded for review to tertiary centers.

Conflict of interest: none

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Fig 6. a) Two-dimensional image with HD flow in a transverse plane at the level of the cervical region, in which the umbilical cord vessels are seen surrounding the fetal neck in a third-trimester pregnancy; b) Two-dimensional image with HD flow of a longitudinal plane at the level of the cervical region, in which the umbilical cord vessels are seen around the fetal neck, and a quadruple nuchal cord can be identified, in a third-trimester pregnancy; c) Three-dimensional power Doppler at the level of the cervical region, in which the umbilical cord vessels are seen around the fetal neck and a quadruple nuchal cord can be identified, in a third-trimester pregnancy.

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