J Med Ultrasonics (2012) 39:43–44 DOI 10.1007/s10396-011-0333-8

LETTER TO THE EDITOR

Antenatal three-dimensional sonographic features of placental shelf Toshiyuki Hata • Tamaki Fujiwara • Megumi Ishibashi • Eri Kuwamura • Chiaki Tenkumo • Go Ishihara

Received: 15 August 2011 / Accepted: 19 September 2011 / Published online: 29 October 2011 Ó The Japan Society of Ultrasonics in Medicine 2011

To the Editor, The sonographic appearance of tissue contiguous with the edge of the placenta that protrudes into the amniotic cavity is called a placental shelf, and this shelf is considered to represent a circumvallate placenta [1, 2]. A circumvallate placenta in the third trimester may cause placental abruption, preterm delivery, fetal growth restriction, and perinatal death [3]. However, Shen et al. [2] reported that an early second-trimester placental shelf appears to be a common, benign, and transient sonographic finding, and never persists to the third trimester. We describe a case of an early second-trimester placental shelf diagnosed by conventional two-dimensional (2D) and three-dimensional (3D) ultrasound, but a partially circumvallate placenta was confirmed after delivery in the present case. A 35-year-old woman, gravida 4, para 3, was referred to our ultrasonography clinic because of suspected amniotic band syndrome at 18 weeks and 2 days of gestation. Conventional 2D ultrasound (Voluson E-8, General Electric Medical Systems, Kretztechnik, Zipf, Austria; curvilineararray transabdominal transducer, 2–5 MHz) revealed typical findings of a placental shelf (Fig. 1). 3D ultrasound (Voluson E-8, General Electric Medical Systems, Kretztechnik, Zipf, Austria; curvilinear-array transabdominal T. Hata (&)
T. Fujiwara
M. Ishibashi
E. Kuwamura
C. Tenkumo Department of Perinatology and Gynecology, Kagawa University School of Medicine, 1750-1 Ikenobe, Miki, Kagawa 761-0793, Japan e-mail: [email protected] G. Ishihara Department of Obstetrics and Gynecology, Mitoyo General Hospital, 708 Himehama, Toyohama-cho, Kanonji, Kagawa 769-1695, Japan

transducer, 2–5 MHz) clearly depicted its features, i.e., a smooth, round, and thick free edge with a triangular shape (Fig. 2). The placental shelf was not attached to any fetal parts, and there was no fetal abnormality. The shelf could not be detected 3 weeks later. A healthy male infant weighing 2,604 g was delivered by elective cesarean section at 37 weeks and 4 days of gestation, with Apgar scores of 8 and 9 at 1 and 5 min, respectively. The placental weight was 480 g, and the macroscopic findings revealed a partially circumvallate placenta (Fig. 3). There have been some reports of antenatal detection of a placental shelf using conventional 2D ultrasound [1, 2]. However, visualization of the continuity and extension of the placental shelf was not easily accomplished with conventional 2D ultrasound. There has been only one reported case of a placental shelf diagnosed by prenatal 3D ultrasound [2]. As shown in the present and previous reports, more detailed information on the placental shelf was obtained by means of 3D ultrasound. In particular, the special relationship between the placental shelf and fetus visualized by 3D surface-rendered display was more readily discernible as compared with conventional 2D ultrasound. 3D ultrasound has the potential to supplement conventional 2D ultrasound in diagnosing a placental shelf. Moreover, 3D sonographic images provide entirely new visual experiences for examiners and couples owing to the near-photographic depiction of the placental shelf and fetal conditions in utero. Shen et al. [2] detected 17 placental shelves (11.2%) in 152 consecutive anomaly scans performed between 13 and 16 weeks of gestation. In their study group, early secondtrimester placental shelves rarely persisted to mid-gestation, and never to the third trimester. All placentas with early second-trimester placental shelves were normal, and there were no placenta-related perinatal problems [2]. In

123

44

J Med Ultrasonics (2012) 39:43–44

Fig. 1 Conventional two-dimensional sonographic transverse view of the placental shelf (arrow) at 18 weeks and 2 days of gestation. P placenta, UC umbilical cord Fig. 3 Gross specimens of the partially circumvallate placenta (arrow)

the present case, the placental shelf was first noted at 17 weeks of gestation, and could not be detected at 21 weeks. The pregnancy course was uneventful, and the fetus was normal. However, a partially circumvallate placenta was identified after delivery. Close placental examination after delivery should be performed if an early second-trimester placental shelf is noted. Conflict of interest

The authors declare no conflict of interest.

References

Fig. 2 Three-dimensional ultrasound surface-rendered view of the placental shelf (*) at 18 weeks and 2 days. Whole images of the placental shelf are clearly shown. P placenta

123

1. McCarthy J, Thurmond AS, Jones MK, Sistron C, Scanlan RM, Jacobson L, Lowensohn R. Circumvallate placenta: sonographic diagnosis. J Ultrasound Med. 1995;14:21–6. 2. Shen O, Golomb E, Lavie O, Goldberg Y, Eitan R, Rabinowitz RR. Placental shelf—a common, typically transient and benign findings on early second-trimester sonography. Ultrasound Obstet Gynecol. 2007;29:192–4. 3. Disease and abnormalities of the placenta. In: Cunninghan FG, Gant NF, Leveno KJ, Gilstrap III LC, Hauth JC, Wenstrom KD (eds.) Williams obstetrics, 21st international edn. McGraw-Hill: International edition. 2001; p. 827–51.