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Case Report
Website:
www.afrjpaedsurg.org
Thoracic heteropagus conjoined twins
associated to an omphalocele: Report of a
case and complete review of the literature
DOI:
10.4103/0189-6725.194670
Quick Response Code:
Kotti Ahmed, Ben Dhaou Mahdi, Zitouni Hayet, Louati Hamdi, Jallouli Mohamed,
Mhiri Riadh
of the twins and eventuates in an incomplete, parasitic
twin attached to a fully developed twin.[3]
ABSTRACT
Heteropagus twins are an extremely rare event
with an incidence of 1–2 million live births that
represents, sometimes, a real challenge for paediatric
surgeons. The majority of cases have complete
or partial duplication of the pelvis and/or lower
extremities. Thoracic heteropagus conjoined twins
is a rare condition in which a grossly defective
foetus (the parasite) is attached to the thorax of the
main foetus (the autosite). We describe a case of
a parasitic heteropagus attached at the chest wall
with a rare presentation of giant exomphalos on the
autosite. In this situation, the separation procedure
was simple after a well‑done anatomic study using
X‑ray, ultrasonography, magnetic resonance and
echocardiogram are performed.
Key words: Asymmetric conjoined twins,
heteropagus twins, incomplete conjoined twins,
omphalocele, omphalopagus parasite,
parasitic twins
The parasite is totally dependent for growth on the host,
usually acardiac, anencephalic, rarely contains thoracic
organs, usually demonstrates lower limbs, trunk and
sometimes dysplastic upper extremities with little or no
movement on them, rudimental intraabdominal organs
is a possible finding as well. In asymmetrical twin sets,
the most common presentation is omphalopagus joined
at either hypogastric or suprapubic region, whereas
epigastric attachment is sparse.[4]
Being such a complex and rare occurrence, the surgical
approach always poses a challenge for the surgical
team, especially when facing the need for closure of a
large defect. We present a case of successful surgical
treatment of a parasitic heteropagus attached at the
chest wall with a rare presentation of giant exomphalos
on the autosite and no pleural involvement.[2]
CASE REPORT
INTRODUCTION
Heteropagus twin is an extremely rare event with an
incidence of 1–2 million live births.[1] Heteropagus twin
refers to a type of conjoined twin in which an incomplete
smaller (parasitic) twin is attached to and dependent on
an otherwise normal host twin (termed the autosite).[2]
The aetiopathogenesis of conjoined twins has yet to
be determined. It is postulated that heteropagus twin
occurs as a result of selective ischaemic damage in utero,
thereby resulting in death and partial resorption of one
A male infant was born at the hospital.
His birth history consisted of a normal spontaneous
vaginal delivery after 40 weeks of uncomplicated
gestation. He had a given weight 4400 with Apgar scores
of 7 and 9 at 1 and 5 min, respectively. Birth weight was
including both autosite and parasite.
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Department of Pediatric Surgery, Hedi Chaker Hospital, 30219 Sfax,
Tunisia
For reprints contact: reprints@medknow.com
Address for correspondence:
Dr. Kotti Ahmed, Department of Pediatric Surgery, Hedi Chaker Hospital,
30219 Sfax, Tunisia.
E‑mail: dr.kotti.ahmed@gmail.com
Cite this article as: Ahmed K, Mahdi BD, Hayet Z, Hamdi L, Mohamed J,
Riadh M. Thoracic heteropagus conjoined twins associated to an omphalocele:
Report of a case and complete review of the literature. Afr J Paediatr Surg
2016;13:209-12.
© 2016 African Journal of Paediatric Surgery | Published by Wolters Kluwer - Medknow
209
Ahmed, et al.: Thoracic heteropagus conjoined twins associated to an omphalocele
The mother was 33 years old (gravida 3, para 1). She
had been submitted to ultrasonography (US), and the
malformation had not been identified. No congenital
abnormality had been documented in the patient’s
family history. No history of maternal medication
use or exposure to radiation during pregnancy was
reported.
reached the sternum. The omphalocele sac was excised
circulary. The abdominal cavity was exposed. The
vascular pedicle of the parasite arose from the pedicule
intercostale of the autosite. Two kidneys, the ureters, the
bladder of the parasite and segments of atresic bowel
were identified easily. There were no intrathoracic
organs in the parasite.
The malformation consisted of a well‑developed
autosite, onto who’s from the upper left part of
the thorax, the parasite was attached above a giant
omphalocele. The parasite twin was attached to the
thorax at the top of the nipples. The autosite was active
and appeared normal except for the omphalocele.
Both ends of the parasite’s bowel were blind, without
any connection to the autosite’s gut. The autosite’s
intraperitoneal organs were completely normal in
appearance. The autosite had a vesicular bifidity
[Figure 2]. The parasite was separated by ligating the
vessels, removing the amniotic sac and hypoplastic
intestines without difficulty.
The parasite consisted of two hypoplastic arms and
thorax, a misshapen trunk, a small abdomen, a pelvis,
and two well‑formed legs. Examination of the perineum
showed genitalia: Small well‑developed penis, and
empty scrotum and no an anal opening. There was a
total lack of movement in its extremities [Figure 1].
Radiologic studies, US and magnetic resonance
imaging (MRI) of the autosite showed no significant
anomaly. The result of echocardiography of the autosite
was normal.
However, the parasite showed no musculature in
the arms and legs (only skin, fat and bone), bone
malformation (where the hypoplastic arms were
attached).
After preparation, the newborn was operated on.
Surgical separation of the twins was performed on
the 7th day after birth. The parasite was attached to
the host by skin, subcutaneous tissue, muscle, and
fascial layers. The incision was extended cranially and
a
The post‑operative evolution had no complication. The
patient was able to eat on the 7th day after surgery, and
the thorax was stable with a satisfactory oximetry.
The patient was discharged from hospital 20 days
post‑operatively.
DISCUSSION
As a consequence of their infrequency, the heterogeneous
terminology, and underreporting of abnormalities,
epidemiologic data regarding heteropagus twins have
been limited.[1,5,6]
Conjoined twins are mostly monochorionic‑monoamniotic
twins and categorised as symmetrical (diplopagus) and
asymmetrical (heteropagus) forms on the basis of the
sizes of twins attached at any part of their body. The
exact aetiopathogenesis is unknown, but most authors
consider it to be a result of an incomplete division of
the embryonic disk during the first trimester.
b
Figure 1: (a and b) Preoperative aspect of thoracopagus: The parasite is
attached to the chest wall of the autosite associated with omphalocele
210
The thoraco‑abdominal wall defect and the omphalocele
were closed without difficulty [Figure 3].
October-December 2016 / Vol 13 / Issue 4
Figure 2: Pre‑operative aspect of a vesicular duplicity
African Journal of Paediatric Surgery
Ahmed, et al.: Thoracic heteropagus conjoined twins associated to an omphalocele
Conjoined twins have been classified as cephalopagus,
thoracopagus, omphalopagus, ischiopagus, parapagus,
craniopagus, pygopagus and Rachipagus.[15]
Figure 3: Post‑operative aspect
In heteropagus form, a smaller incomplete parasite is
fused to a complete autosite, usually in the hypogastric
or suprapubic region of the host. In some extremely
rare cases, the junction is above the umbilicus, which
is named as epigastric heteropagus twins.[7‑9]
Joined twins at the site of either abdomen or thorax
result from the union at the extreme rostral aspect
of the early embryonic disc, primarily involving
only the septum transversum in omphalopagus,
but both the septum and the cardiac primordium
in thoracopagus. The latter comprises a small
portion of all reported heteropagus twins because a
defective heart of the autosite is unable to support
the viability of both foetuses. [4,10] Albeit by the
definition, thoracopagus parasiticus must involve
abnormal heart (duplication of cardiac primordium
in symmetrical twins), some authors have reported
heteropagus parasiticus without heart involvement
in the autosite and classified this as thoracopagus
according to the site of attachment only. [11,12]
Other authors have classified cases of asymmetric
doubling as epigastric heteropagus when the parasite
was connected at the chest wall because of giant
omphalocele.[13,14]
The criteria for thoracopagus parasiticus in recondite
cases are obscure since they include only the site of
union and heart involvement.
In the latter case, the autosite was diagnosed with
major congenital heart anomalies and the irrigation
of the parasite was sustained by the vascular pedicle
originating from the artery of the thoracic wall of the
autosite, as there was no pleural cavity involvement in
the communication between foetuses.
Most infants with heteropagus are male.
African Journal of Paediatric Surgery
Embryonic death of parasitic twin leaves behind body
parts vascularised by the autosite in heteropagus.
Although the aetiology of embryonic death is yet
unknown, it is thought to be caused by ischaemic
atrophy and/or insufficient cardiac function of the
parasite or vascular steal from the autosite. The
parasite is usually acardiac except in a few cases and
is supplied by the vessels arising from different regions
of the autosite, including liver, left internal mammary
artery, epigastric artery, umbilical vessels and falciform
ligament.[7]
Antepartum diagnosis of parasitic twinning plays
an important role in management. Outcomes are
generally favourable. Therefore, heteropagus twins
should be distinguished from more severe congenital
malformations to avoid unnecessary termination.
At least, three examples exist in which the authors
explicitly note the failure of prenatal sonographic
assessment to detect heteropagus twins.[1,16‑18]
Prenatal diagnosis can be established by ultrasonographic
examination or MRI and is becoming increasingly
frequent.[2]
Mode of delivery of heteropagus twins is only described
in 34 articles from 1984 to the present. Eighteen
pairs (53%) of twins were delivered vaginally and
10 (29%) by caesarean delivery.[1]
Pre‑operative imaging before the separation of
symmetric conjoined twins can be quite extensive.
Because sharing of organs and vascular connections
between autosite and parasite of heteropagus pairs
tend to be less extensive, pre‑operative imaging used
has been more limited. Computed tomography (CT),
ultrasound and MRI are the most common initial studies
in all types of heteropagus twins.
In addition to CT and MRI, echocardiography is often
added for thoracopagus and omphalopagus heteropagus.
Several groups have used Doppler ultrasound[17,19‑21] or
magnetic resonance angiography[16,22] to identify the
vascular pedicle sustaining the parasite before surgical
separation. Vascular connections are often determined
intraoperatively. In general, regional CT or MRI as
well as echocardiography are advisable pre‑operative
imaging modalities.
October-December 2016 / Vol 13 / Issue 4
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Ahmed, et al.: Thoracic heteropagus conjoined twins associated to an omphalocele
The parasites have been reported to be nourished via
the vessels of falciform ligament, intercostal arteries,
mesenteric arteries, epigastric arteries, left subclavian
artery and brachiocephalic trunk.[4]
5.
6.
7.
Omphalocele was present in approximately half of
epigastric heteropagus, but major omphalocele was
seen only in a few cases in thoracopagus. A common
ventricle has been described in only three more reports
in the reviewed literature.[4]
Options for treatment of such twins are dependent
largely on the anatomy of the cardiovascular system.
The use of sonography followed by MRI in evaluating
the anatomy of conjoined twins is a valuable assessment
sequence that plays a significant role in predicting
prognosis for survival, and making decisions for
treatment and follow‑up.[7,23]
8.
9.
10.
11.
12.
13.
Separation is usually performed in a single operation.
14.
Non‑lethal complications ranged from an incisional
hernia to teratoma formation at the site of retained
parasite tissue.[1]
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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