Document 15235

76
mbryology
ACARI}IA ACEPHALUS TWIN . A CASE REPORT
Dr. Manala S., Dr. Dakshayani K.R.
Dr. Dakshayani K.R.
Professor and Head
Department of Anatomy
Mysore Medical College
And Research Institute
Mysore - 570 001
Mobile no - 9448739656
E-mail dakshay [email protected] gmail. c om
Dr. Mangala S.
Post graduate
Department of Anatomy
Mysore Medical Coltege
And Research Institute
Mysore - 570 001
Mobile no - 9986019997
E-mail - dr [email protected]
:
monochorionic, vascular anastomoses,
ABSTRACT
During routine fetal autopsies conducted in
the department of Anatomy', a rate case of
fullterm female Acardia Acephalus twin was
observed, The autopsy findings revealed
acardiac twin showing right sided diaphragmatic
hernia, absence of brain, spinal cord,
respiratory system, upper Iimb Amelia with
rudiments of heart and urogenital system,
partially developedcm and syndactyly of right
i
foot.
)
reversed arterial perfusion
INTRODUCTION
Acardia is a rare and severe congenital
malfoimation unique to mon ozygottc,
monochorionic multiple gestation with vascular
anastomoses which is hemodynamically
srgmfrcant
It
iS thE TESUII Of TWIN REVERSAL
ARTERIAL PERFUSION SEQUENCE
Fetal acardia is a rare dysmorphic problem
which is unique to monochorionic pregnancies
occurs with an incidence of l:35000 deliveries
with vascular anastomoses.'It is due to a
sequence described as TRAP Twin Reversed
Arterial Perfusion, with an incidence of I in
SINGLEPLACENTA. This condition has a
35,000 births.
The present case gains significance because
and
in l7o of monozygotic
gestation with
fernale preponderance.
Out of 4 different types of Acardia twins,
Acardia Acepahlus is the commonest.
of its pattern of hemodynamically significant
The present case report adds to the literature
anastomotic circulations in monochorionic,
monozygotic multiple gestation.
for typical example of an acardiac acephalic
KEY WORDS
MATERIALS AND METHODS
Acardia Acephalus, mono zY gotic,
monster.
A 22 year old second gravida with no
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significant past history delivered twins with gestational bge of about 34 weeks at K.R. Hospital, Mysore attached to MMC&RI.
The first twin was
a
female weighing 2 kgs
and was Acephalic monster (present case). The
second twin born after 5 minutes was a live
normal female baby weighrng 1.5 kg.
Mother has a Zyearold healthy male child
from previous conception.
Autopsy of the acardiafetus was done in
the Department of Anatomy, MMC & R[, and
x-ray of the same was taken in the department
of Radiology, K.R. Hospital attached to
MMC&RI.
OBSERVATION AND RESULTS
1.
Blunt and covered with sparse hair.
2. Absence of lungs
with empty pleural sac.
3. Rudimentary tubular cardia.
4. Incomplete diaphragm
5. Normal ureters
6.
with Right fallopian tube.
CTEV deformity bilaterally.
External features:
In the present case, the fetus was covered
with thick skin that was soft and oeddmatous.
There was no distinct Head. Instead there was
a blunt cranial end covered with sparse hair and
some small cranial bony remnants.
Upperlimbs were absent. Lowerlimbs were
near normal except for BIL CTEV. Right foothad four digits with syndactyly of third and fourth
digits.
1.
Rudimentary cranial skeleton.
2.Yertebral column
3. Pelvic girdle bones
4. CTEV with Thrsal bones.
Irft
foot-had four digits.
Anterior abdominal wal I -compl ete, external
genitalia-normal, suggestive of female sex.
, Anal orifice-patent.
AUTOPSYFINDINGS
78
CRANIOTO-MY : revealed absence of
brain and spinal cord.
THORACOTOMY : absence of trachea
and lungs rudimentary tubular cardia with
arterial and venous ends. Incomplete
SEQUENCE (TRAP sequence),'unique to
monozygotic twinning. The etiology of acardia
is either a primary heart defect in one twin or
reversed arterial perftrsion from the pump tw'in
to acardiac twin. (Craven C et al 1999).
LAPAROTOMY : revealed oesophagus
with proximal blind end with apafiof stomach
It represents a variant of conjoined twins in
which thejunction is the chorionic circulation.
Normal twin is the 'pump twin'. Acardiac twin
is the 'perfused or recipient twin'.,The'pump
herniating i,nto right side o{thror:acic cavity.
twin provides circulation forbothitself and the
devel opment of diaphragm
acardiac twin.
Parts'of duodenum present
Rudimrints of liver seen.
Bilateral kidneys with ureters and urinary
bladder seen.
Rudiments of uterus with right fallopian trrbe
and ovary present.
Largeblood vessels of abdomen seen.
Absence of coils of intestine, spleen and
pancfeas.
RADIOLOGICAL FINDINGS:
Revealed a disproportionate massof soft
tissue. Rudimentary cranial skeleton was seen.
Vertebral column was present. Ribcage was
with absence of upper limbs and pectoral
girdle. Pelvic girdle present with lower limb
seen
bones.
DISCUSSION
EMBRYOLOGY: Acardiac twinning is the
result of disruption in norganogenesis due to
arterial-placental anastomosis in the early
embryonic period. This is also called as TWIN
REVERSED ARTERIAL PERFUSION
The perfused twin has no direct vascular
connectilon with placenta and the blood enters
directly through a single umbilical artery and
exits thtough the urnbilical vein.
TRAP sequence is caused in the embryo
by a sizable artery to artery placental shunt,
often ,accompanied by vein to vein shunt.
(Cunnigh*tr F9 et al 2005).
The placental pressure of one twin
overpowers the other who then has reverse
blood flow from the co-twin.
The ,'used' arterial blood reaching the
recipient twin preferentially gogs to the iliac
yessels and thus perfuse only the lower pan of
the body, leading to disnrption ordeterioration
of growth and development of the upperbody.
Hypoxicflow via arterial communications from
the 'pump' twin results in panial reabsorption
of normal tissues of acardiac fetus.
TYPES: According to Izquierdo L et al
IggL Four different types of acardiac twins
have been categonzed based on the degree
cephalic and truncal maldevelopment.
of
1. ACARDIA ACEPHALIC - where no
cephalic structures are present.
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2. ACARDIA ANCEPS - in which some
cranial structures are present with or without
secondary to prematurity. The combined
circulation of purnp twin may result in
neural tissue.
cardiomegaly and congestive heart failure.
3. ACARDIA ACORMUS - in which
cephalic structures are present with no truncal
The progno.sis worsens when
polyhydramnios, pre term labour or cardiac
decompensation complicates the condition.
Monozygotic twins have also been shown to
have a higherfrequency of neural tube detbcts
than singletons. All acadiac twins die and
about one thirds of the pumped twin die in
perinatal period.
structures.
4.
ACARDIA AMORPHUS - which has
no discernible cephalic ortruncal structures.
According to Krause W and Bejdl W
(1948) Compression of the cephalic pole of
the embryo prohibiting curving and fusion of
the primitive heart tube has been suggested to
@ the basic cause of this anomaly.
As the umbilical cord of the acardiac twin
is usually hypotrophic, it is likely to be torn
during manipulation resulting in death of
normal fetus due to blood loss through
anastomosis. (Sanfilippo J er al lg79)
According to Monie IW ( Ig70) most
acardiacs are reported to have single umbilical
aftery indicating penistence' of transitory single
artery phase (which is normal upto carnegie
stage 12).
Allen VMI et al (1983) found thar about
half of the cases studied by him had
"
Since the goal in such case is intemrption
of vascular anastomosis between pump and
recipient twin, improved imagrng techniques
like two dimensional, tlree dimensional, and
transvaginal ultrasonographic Doppler have
made diagnosis of acardia possible even in
chromosomal abnormalities even though the
condition is said to be sporadic. An abnormal
karyotype was found in perfused twin, while
karyotype was foundnormal in pump twin.
the first trimester of pregnancy by
DETECTING INVERSION OF
According to study by Groeninghen VJC
et al (1985) acardiacs had normal karyotype.
VASCULAR FLOW in recipient acardiac
twin. (Dhall U et al 2005).
CONCLUSION
Early diagnosis may allow measures to be
taken that may help to reduce the risk if such
The present case of Acardia acephalus is
one of the two patterns of hemodynamically
complications by prenatal planning for
si
gnifi cant anastomotic circul ations, unique to
monozygotic, monochorionic twin pregnancy.
(Cunningham FG et al 2005).
Acardia acephalus gains importance in view
of complex placental, vascular anastomotic
pattern in multiple gestation. A reported fifty
percent mortality in pump twin is noted usually
neonatal surgery.
REFERENCES
1. Allen VMI, Smith DW Shepard TH,
1983. Twin reversed arterial perfusion
(TRAP) sequence. A study of L4twin
pregnancies with acardius. Seminars in
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80
1985. An acardiac acephalic monster.
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Iggg.Embryo, fetus and placenta:
Normal andAbnormal. Danforth's '
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Acardia Acephalus Monster - A Case
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