|Year : 2020 | Volume
| Issue : 4 | Page : 245-249
Twinning and birth defects: Rachipegal heteropagal twins and acardiac twins
Padmavathi Devi Chaganti, Maruthi Devi Karri, Sreedhar Bora, Pamidipalli Vamsi Vihar
Department of Pathology, Guntur Medical College, Guntur, Andhra Pradesh, India
|Date of Submission||24-Oct-2020|
|Date of Acceptance||17-Dec-2020|
|Date of Web Publication||6-Jan-2021|
Dr. Maruthi Devi Karri
Associate Professor of Pathology, Guntur Medical College, Guntur, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Twin pregnancies are associated with multiple birth defects. The increase in twinning was attributed to fertility treatments. Twins were supposed to be associated with increased risk of congenital malformations. Among the twins, monozygotic twins were associated with more malformations then dizygotic twins. Heteropagus conjoined twins are asymmetrical conjoined twins where one twin is normal and the other is anatomically incomplete and grossly defective, attached externally, with or without internal connection. Heteropagal Conjoined twins were classified based on the site of their union, and when the fusion occurs at the level of the spine it is called Rachipagal heteropagal twin. One of the most important complication of Monochorionic placenta is Twin to twin transfusion syndrome. The major major defect is in recipient twin there was lack of well developed cardiac structure, and the blood supply was maintained through placental vascular anastomosis with normal twin. This sequence was described as the twin reversed arterial perfusion ,also known as Acardiac Twinning. Here we are going to present two rare cases of Rachipegal Heteropagal twin and Acardiac twin.
Keywords: Acardiac twin, congenital malformations, Rachipegal Heteropagal twin, TRAP sequence, twin pregnancy
|How to cite this article:|
Chaganti PD, Karri MD, Bora S, Vihar PV. Twinning and birth defects: Rachipegal heteropagal twins and acardiac twins. J NTR Univ Health Sci 2020;9:245-9
|How to cite this URL:|
Chaganti PD, Karri MD, Bora S, Vihar PV. Twinning and birth defects: Rachipegal heteropagal twins and acardiac twins. J NTR Univ Health Sci [serial online] 2020 [cited 2021 Jan 17];9:245-9. Available from: https://www.jdrntruhs.org/text.asp?2020/9/4/245/306121
| Introduction|| |
Twin pregnancies are associated with multiple birth defects. The increase in twinning was attributed to fertility treatments Twins were supposed to be associated with increased risk of congenital malformations. Among the twins, monozygotic twins were associated with more malformations than dizygotic twins.
Rachipegal Heteropagal Twin and Acardiac Twin were rare complications of Monozygotic Multiple Pregnancies. The incidence of rachipegal heteropegal twin constitute less than 1 in 1 million births, and the incidence of Acardiac fetus was one in 35,000 live births.
Heteropagus conjoined twins are asymmetrical conjoined twins where one twin is normal and is called an autosite. The other is anatomically incomplete and grossly defective, attached externally, with or without internal connection, and is called a parasite. They are extremely rare and constitute less than 1 in 1 million births. Heteropagal Conjoined twins were classified based on the site of their union, and when the fusion occurs at the level of the spine it is called Rachipagal heteropagal twin. Herewith, a case of heteropagus twin of the Rachipagus type was reported.
Among twin pregnancies, 20% of them are monochorionic, and the most important complication of Monochorionic placenta is Twin to twin transfusion syndrome (TTTS) There was a shift of blood from donor twin [Pump Twin] to recipient twin through placental vascular connections. This establishes reverse arterial perfusion in the umbilical cord of the recipient twin. a major defect in recipient twin was lack of well-developed cardiac structure, and the blood supply was maintained through placental vascular anastomosis with normal twin This sequence was described as the twin reversed arterial perfusion, also known as Acardiac Twinning. Acardius is one of the rare complications of Monozygotic Monochorionic Pregnancies. The pump twin was at a higher risk of heart failure.
Here we are going to preset two rare cases of Rachipegal Heteropagal twin and Acardiac twin.
Institutional ethics committee clearance number – GMC/IEC/124/2018.
| Case Report 1|| |
A 3-day-old term, male neonate, delivered by LSCS, weighing 3 Kg, product of non-consanguineous marriage, was admitted with supernumerary legs and primitive genitalia in between, mimicking pelvic girdle, attached to the lumbar region of the neonate [Figure 1]. His 1-min APGAR score was 9. Feeds were accepted and tolerated normally. There was no history of twin deliveries in families of both the parents or usage of any medication, including fertility drugs, exposure to radiation, or exanthematous fever during the first trimester of pregnancy. Mother was 28 years old. Pelvic girdle like structure attached to the lumbar region of the baby did not show any movement either spontaneous or after stimulation. It consisted of two rudimentary lower limbs fused proximally and attached to the baby at the level of L3 vertebra. There was a lipomeningocele at the site of attachment. Radiograph of the parasitic limb showed the bone structures of the femur, tibia, and fibula and malformed fused ileac bones attached to the sacrum at the level of L3-L4 vertebrae [Figure 2]. There was only one spinal canal. The posterior arch was absent from L2 to L5. The parasitic limb was excised after ligating the feeding vessel. The lipomeningocele located at the base of the parasite was excised, the Dura was repaired, and the wound was closed. The intra-Dural content included normal roots with a single spinal cord. The wound healed well, and the baby was discharged on the 10th postoperative day. During the follow-up visits, the child was found to be gaining weight with normal milestones of development. There were no neurological deficits or hydrocephalus.
|Figure 1: Gross Image Of Rachipegal Heteropagal Twin showing Pelvic girdle like structure along with two rudimentary lower limbs fused at lumbar region|
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|Figure 2: x ray image of Rachipegal Heteropagal Twin showing malformed fused ileac bones attached to the sacrum at the level of L3-L4 vertebrae|
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We received two specimens.
Sp. 1: Heteropagal twin, measuring 13 x 10 x 5 Cm, showing both lower limbs and incompletely developed male genitalia.
The microscopic examination from incompletely developed male organs showed only nerve bundles and blood vessels. There was no evidence of any organs.
Sp. 2: Grey-brown mass of size 2 x 2 x 1 Cm.
Microscopic examination showed flattened meningothelial lining, glial tissue, mature adipose tissue, smooth muscle bundles, blood vessels, and nerve bundles.
A diagnosis of Rachipagal Heteropagus with lipomeningocele was made.
| Case Report 2|| |
A 28-year-old female Gravida3Para2 was Delivered by cesarean section. The Prenatal ultrasound Showed a twin reversed arterial perfusion (TRAP) sequence, with a normal vital male fetus (Twin 1) and an acardiac fetus [Twin 2].
There was no history of twin deliveries, fertility medication, or Consanguinity in families of both the parents.
A healthy baby was delivered with APGAR Score of 8 at 1 min and 10 at 5 min.
The umbilical cord had three vessels'. The birth Weight of the baby was 3,150 g. The acardiac twin with a single umbilical artery had separate amniotic sac and Monochorionic Placenta.
We received Acardiac Twin. The acardiac twin measured 16 cm in length, and it was showing rudimentary head and limbs with no discernible neck or demarcation between the head and trunk. A rudimentary face had no separation of the eyelids. The upper limbs and lower limbs were rudimentary. The anus was absent. In the genital region, there were no discernible genital organs. [Figure 3] The X-ray showed a grossly deformed mass of fetal body with the absence of differentiation of appendicular Skelton and multiple poorly differentiated vertebral segmentation.
|Figure 3: Gross image of Acardiac Twin showing udimentary head and limbs with no discernible neck or demarcation between the head and trunk|
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No visible cranium or Facial bones and non-developed lungs, a mass of bony tissue in the expected region of bony pelvis without any differentiation [Figure 4].
|Figure 4: x ray image of Acardiac Twin showing absence of differentiation of appendicular Skelton and multiple poorly differentiated vertebral segmentation|
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| Discussion|| |
The rise in maternal age and the use of assisted reproductive technologies were associated with increased congenital malformations. Among the twins, Monozygotic twins were associated with more congenital malformations. Rachipegal Heteropagal Twin and Acardiac Twin are rare complications of Twin pregnancy. The incidence being o less than 1 in 1 million births for rachipegal heteropagal twin and one in 35,000 live births for Acardiac twin.
Conjoined twins are associated with the usage of clomiphene and griseofulvin. Female preponderance is seen in symmetrical conjoined twins, whereas in Heteropagus, both sexes are equally affected. In our case, there was no history of usage of drugs and both babies were male babies.
In Heteropagus conjoined twins, one twin is nearly normal and is called “autosite,” and the other twin is anatomically incomplete and is called “parasite.” The parasite is physically attached to the autosite. The cause of the merger was not known. Heteropagal twins were classified based on the site of the merger. Eight types of mergers were described. When the fusion is at the spine, it is called Rachipagus, in which the union most commonly occurs at the posterior arch of the spine. Rachipagus-heteropagus conjoined twins are extremely rare, and their incidence is less than 0.1 in 10,000 live births, and the reported cases do not exceed 30.
In Heteropagal twins, one of the embryos disappears with the survival of certain parts attached to the normal embryo near or at the junctional area. No associated anomalies or neurological deficit is noticed in the autosite.
Two major theories were proposed to explain the occurrence of Rachipagal twins. One is fusion theory, which explains that the fusion occurs by the end of the second week of gestation when both embryos fuse to form two embryonic discs with a single yolk sac. DNA analysis of both autosite and parasite shows that they are homozygous. The fission theory postulates that there is an incomplete division of embryo followed by fusion occurring 14 to 15 days after fertilization. The parasite usually contains bones of the limbs but rarely can contain beating heart, neural tube structures, normal-looking brain, rarely glandular tissue, intestine, and anal orifice. In the present case, DNA analysis was not done as the parents did not give permission.
The incidence of TRAP or Acardiac twin is one in 35,000 live births. Acardiac anomaly is a rare complication of Monochorionic Placenta in which one twin or recipient twin or acardiac twin will not have a heart or will have a non-functioning heart. Recipient Twin is pumped by co-twin or pump twin through placental vascular connections., There are superficial intertwining vascular anastomoses, which results in a bypass of placental tissue. These connections can be from Artery to Artery [A-A] connections or vein to vein [V-V] connections in the superficial part of vessels of fused Monochorionic placenta. There was a loss of connection to placental villi for Acardiac twin. The reverse arterial perfusion in the umbilical cord of recipient twin was described as the twin reversed arterial perfusion, also known as Acardiac Twinning.
Pathogenesis was unknown, but many theories were put forwarded. One theory proposed was in the fused placenta in early embryogenesis; there were umbilical vascular anastomoses that results in vascular disruption leading to tissue hypoxia. This results in atrophy of the heart. The second theory proposes that genetic defect in the development of the heart in a twin was followed by anastomosis of umbilical vessels. Chromosomal defects were identified in 50% of cases in TRAP syndrome. Ferrira et al. proposed that there were no chromosomal anomalies in most of the acardiac twins, and 33% of cases of Monozygotic twins might show karyotypic changes. They also proposed that there was a primary defect in the development of the heart, and the acardiac twin survives because of the TRAP sequence. The second hypothesis proposed was both twins begin as normal fetuses but reversal of circulatory blood flow in early stages of embryogenesis results in defective development of heart.
The associated anomalies in Acardiac twin were a partial or total absence of cranial vault, holoprosencephaly, absent facial structures, anophthalmia, microphthalmia, cleft lip, cleft palate, absent or rudimentary limbs, absent lungs or heart. Acardiac twins were classified based on the anomalies as Hemicardius if the heart is incompletely formed and Holocardius if the heart is completely absent, acephalus if the head is absent, anceps if the head is poorly formed, acormus if the head is only present and amorphous if the head is unrecognizable. In our case, acardiac twin showed absence of heart with unrecognizable features [kalyani 10].
Congenital anomalies in pump twin were shown in 9% of cases; in the present case, consent was not given for the examination of pump twin.
| Conclusion|| |
Rachipegal Heteropagal Twin and Acardiac Twin are rare complications of Twin pregnancy.
The obstetrician and Radiologist must be aware of anomalies associated with twinning so that early intervention can be given.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]