Arch Gynecol Obstet (2010) 281:565–567 DOI 10.1007/s00404-009-1219-5
M A T ER N O - F E T A L M E D I C I N E
Prenatal diagnosis of dicephalic parapagus conjoined twins Hakan Camuzcuoglu · Harun Toy · Mehmet Vural · Hasan Cece · Halef Aydin
Received: 10 June 2009 / Accepted: 17 August 2009 / Published online: 28 August 2009 © Springer-Verlag 2009
Abstract Dicephalic parapagus is a rare anomaly of monochorionic twinning. We present prenatal diagnosis of this anomaly with ultrasonography and magnetic resonance imaging. She was at the 19th week of gestation. Even if earlier diagnosis is possible, this was her Wrst examination unfortunately. Baby had two head and a common trunk. This is one of the rarest twinning. Termination of pregnancy is performed and baby is delivered by cesarean section. Imaging Wndings of the case are illustrated and discussed with the autopsy Wndings.
Thoracopagus (joined at the thoracic level) twins are the most common, accounting for 40% of cases, followed by omphalopagus (joined at the abdomen, but often including the lower thorax), accounting for 33% [1]. These two types are subtypes of ventral fusion; also, dorsal and lateral fusion types are present. The term parapagus is used to describe twins fused extensively side to side. We reported prenatal diagnosis of dicephalic parapagus case along with ultrasound and magnetic resonance imaging pictures and autopsy Wndings in a 16-year-old pregnant woman at the 19th week of gestation.
Keywords Dicephalic parapagus · Conjoined twins · Ultrasonography · Magnetic resonance imaging Case Introduction The incidence of conjoined twins is reported to be in a range of 1 in 50,000 gestations. However, if the stillborns are excluded, actual incidence would be 1 in 250,000 live births [1]. They develop from a single fertilized ovum with the most common theory of failure to separate embryonic disc at around 15th day. Twins are classiWed according to the major site of union. Greek word “pagus” is added to denote Wxing to union site.
H. Camuzcuoglu · H. Toy · M. Vural (&) · H. Aydin Department of Obstetrics and Gynecology, Faculty of Medicine, Harran University, Yenisehir yerleskesi, Morfoloji binas Kat 3, 63300 Sanliurfa, Turkey e-mail:
[email protected] H. Cece Department of Radiology, Faculty of Medicine, Harran University, Sanliurfa, Turkey
A 16-year-old nulliparous healthy patient came for her Wrst routine ultrasound examination at the 19th week of gestation. Abnormal twinning was found. Her personal history was uneventful. Her grandmother has had a twin healthy baby in her family history. Transabdominal ultrasonography (Logiq® P5, 3.5 MHz, General Electric, SangdaewonDong, Korea) revealed 19-week-old fetus with two heads with separate necks and one common trunk (Fig. 1). Both ultrasonography and magnetic resonance images showed single cardiovascular system (Figs. 1, 2), placenta, and umbilical cord. These Wndings suggested a diagnosis of dicephalic parapagus conjoined twin. The couple enlightened that this is possibly surgically inseparable twin pregnancy and there is a poor life expectancy. After discussion with patient and her family, pregnancy termination is opted. Although the patient was informed about therapeutic abortion with prostaglandins, she and her family did not for approve this procedure; also risks of uterotomy operation and possible future complications were explained in detail. They requested painless and
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Fig. 1 Transabdominal ultrasonography of dicephalic parapagus twins. Conjoined heart (black arrow) and separate vertebral columns are visualized (white arrows)
rapid intervention with abdominal operation, and took whole responsibility for possible complications with informed consent form. Termination of pregnancy was performed via uterotomy. Postoperative period was uneventful. She recovered in 3 days and discharged without any complication.
Discussion Literature related with this rare type of conjoined twinning dicephalic parapagus cases is very limited. Prenatal diagnosis of these cases can be possible in early pregnancy with ultrasonography. Along with the importance of early diagnosis, undiagnosed cases can cause a variety of problems, especially during vaginal delivery.
Fig. 2 Magnetic resonance imaging of dicephalic parapagus twins. a Axial image of common abdomen and single heart (arrow). b Coronal image, separate heads and laterally fused body with common heart (arrow)
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Arch Gynecol Obstet (2010) 281:565–567
Several embryologic theories of conjoined twinning are proposed in the last decades. The most popular and Wrst was incomplete Wssion of the embryonic disc approximately 2 weeks after fertilization (Wssion theory). However, an up-to-date theory hypothesizes fusion between two previously separate embryologic discs 12 day after the fertilization (fusion theory) [2]. Conjoined twins classiWed according to union site. Grossly, they can be classiWed into three (ventral, dorsal, and lateral union) groups. Parapagus is a type of lateral union [3]. Greek terms are used for classiWcation and “pagus” which means united. Lateral fusion of embryo except cranium usually results in a common abdomen, pelvis and lower extremity. There may be 2–4 arms and 2 or 3 legs [4]. In our case, there were two upper and three lower extremities—one is rudimentary and fused onto perineum (Fig. 3). The name dicephalic parapagus implies completely separate two heads and faces with single heart. Although it is rare, two separate hearts also reported in dicephalic parapagus case [5]. It is possible to separate parapagus twin; however, single heart will aVect prognosis. On an autopsy, one upper and one lower extremity were observed on both the sides of the twins. A rudimentary lower extremity closed to right lower extremity was seen. Genders were identiWed by inspection of internal genital organs. Both fetuses were female. Two hearts were fused in the apex region with a Wbrous band; however, each heart had its own atriums and ventricles and the remaining internal organs were not fused. According to Spencer, hearts of the parapagus twins can be fused or separated [4]. Our case is an intermediate form which has side to side fused two hearts. This can be a matter of discussion whether the separation is feasible as in this case. However, it seems to be diYcult to assert that this case might be a candidate to be separated.
Arch Gynecol Obstet (2010) 281:565–567
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Fig. 3 Clinical images of the dicephalic parapagus twins. a Two upper limbs. b Anterolateral fusion of the chests of the twins; two separate and one common shoulder. c Four lower limb. Two lower limbs are fused and stacked to perineum (arrow)
Prenatal diagnosis of the dicephalic cases can be as early as 10th week of gestation [6] and the prognosis should be discussed individually. As the shared parts are increased, prognosis worsens. If early diagnosis can be achieved, vaginal delivery for termination can be possible. Early and accurate diagnosis of this rare and severe malformation and determination of organ sharing level are crucial for the further management of pregnancy and babies. It is also important to assess their structural integrity or associated malformations to plan management, and identifying the anatomical structural integrity of the hearts is critical at this point. ConXict of interest statement
References 1. Spitz L (2005) Conjoined twins. Prenat Diagn 25(9):814–819 2. Kaufman MH (2004) The embryology of conjoined twins. Childs Nerv Syst 20(8–9):508–525 3. Winkler N, Kennedy A, Byrne J, Woodward P (2008) The imaging spectrum of conjoined twins. Ultrasound Q 24(4):249–255 4. Spencer R (1996) Anatomic description of conjoined twins: a plea for standardized terminology. J Pediatr Surg 31(7):941–944 5. McMahon CJ, Spencer R (2006) Congenital heart defects in conjoined twins: outcome after surgical separation of thoracopagus. Pediatr Cardiol 27(1):1–12 6. Vural F, Vural B (2005) First trimester diagnosis of dicephalic parapagus conjoined twins via transvaginal ultrasonography. J Clin Ultrasound 33(7):364–366
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