My presentation of a clinical case and related review of the topic of conjoint twins from the perspective of a pediatrician

1. Lord Brahma – Hindu mythology

3. “SIAMESE TWINS”

4.  Conjoint twins born in Siam
 ‘Siamese twins’
 1811 -1874
 Considered inoperable
 Lived without separation
 Fathered 21 children
 Lived life as ‘entertainers’
 Died at the age of 63

7.  Among the 13,418 consecutive stillborns surveyed, 6
cases of conjoined twins were identified giving a
frequency of 44.72 per 100,000.
 11 pairs were identified among the 2,425,583 total live
births, a frequency of 0.45 per 100,000.
 The frequency among stillborn infants is 99.34 times
higher than that observed among live births1
Martinez-Frias et al. J Pediatr Surg. 2009

8. Thoraco-omphalopagus

10.  Found to be conjoint (Thoraco-Omphalopagus) intra-
op during Cesarean section
 T1 required bag & mask for 30 seconds
 Respiratory distress in both soon after birth
 Both put on NPCPAP
 CXR at CLR No sharing of bony chest wall
 USG at CLR did not reveal any organ sharing : 2
distinct livers and hearts.

12.  Shifted to Pediatric surgery at 6 hrs of life
 Planned for elective surgery
 Were taken off Nasopharyngeal CPAP on D2 and kept
on free flow oxygen. Continued to have minimal
distress.
 T1 was diagnosed to have # of shaft of left femur. Ortho
advised conservative Mx.
 Started on T/F which were gradually being hiked.

13.  Planned for CECT. PAC obtained.
 Had worsening in the form of not maintaining
saturation on D3. Intubated and put on manual IPPR
and then on SIMV mode of ventilation.
 Cause kept as: ?Pneumonia ? Aspiration syndrome
?HMD. Antibiotics upgraded. Worsening clinical
course.
 Suffered cardiac arrest on D6 of life from which the
babies could not be revived.

14. Twin 1 Twin 2
 Dextrocardia  Levocardia
 AV-VA concordance  Single ventricle
 6 mm displacement of  Single AV valve
STL towards RV   No PS/PDA
EBSTEIN’S ANAMOLY  8 mm OS ASD with LR
 Mild TR shunt
 No  Malposed Great vessels
ASD/VSD/PDA/LVOTO/
RVOTO
No vessel / Chamber sharing seen between twins

15. Discussion
Saptharishi L G

16.  Incomplete embryonic division occurs late
 At around day 13 - 14 of conception1
 Chorion and amnion have already formed by that time
 Conjoint twins  monochoionic monoamniotic twins
Kaufman MH. The embryology of conjoined twins. Childs Nerv Syst. 2004

19.  The Fission theories
 Well established
 Numerous studies
 The “Fusion” theory1&2
 Animal model in Triton embryos + study of more than
1800 reported cases of conjoint twins
 Fusion – ventral or dorsal: at sites of absence of
ectoderm
Spencer. Theoretical and analytical embryology of conjoined twins. Clin Anat 2000

20. Points against Points for
 "the same parts are  No theoretical "fission" of
the vertebrate embryo at
always united to the any stage of development,
same parts“ in any plane, in any
direction can explain
 Ectoderm is non-sticky
(1)the selection of the
 Zona pellucida: observed sites of fusion
hydrophobic (2)the details of the union
(3) the limitation to the
specific areas in which the
twins are found to be
joined.

22.  Factors that induce calcium depression and delayed
implantation encourage uniovular duplication in
general and CJ twinning in particular1.
Steinman G. Mechanism of twinning.V. J Reprod Med 2002

23.  Very rare
 1 in 50,000 to 100,000 births
 Indian incidence ( 1 in 50,000)
 Note : Live born twins are rare as most of them get
spontaneously terminated in utero

25.  Broad categories:
 Ventral fusion: 87%
 Dorsal fusion: 13%
 Most common sites of fusion1:
 Thoraco/omphalopagus : 73%
 Pyopagus 19%
 Ischiopagus 6%
 Craniopagus 2%
Hoyle RM. Surgical separation of conjoined twins. Surg Gynecol Obstet. 1990

27. UK study Spanish study
 Thoraco-omphalopagus  Thoracopagus (58.82%)
(28%)  Diprosopus (11.7%)
 Thoracopagus (18.5%)
 Omphalopagus (10%)
 Parasitic twins (10%)
 Craniopagus (6%)
Kaufman MH. The embryology of conjoined twins. Childs Nerv Syst. 2004
Martinez-Frias et al.J Pediatr Surg. 2009

28.  Embryological Classification*
 Ventral Union (87%)
 Rostral (48%)
Cephalopagus (11%, top of head to umbilicus)
Thoracopagus (19%, conjoined heart)
Omphalopagus (18%, including lower thorax)
 Caudal (11%)
 Ischiopagus (lower abdomen and genitourinary system)
 Lateral (28%)
Parapagus (pelvis and variable trunk)
 Dorsal Union (13%)
 Craniopagus (5%, cranial vault)
Rachipagus (2%, vertebral column)
Pygopagus (6%, sacrum)
*Adapted from Spencer

29.  Conjunction never involving heart or umbilicus:
 Craniopagus: Cranial union only, about 2% of all
conjoined twins.
 Pygopagus: Posterior union of the rump, about 19% of
all conjoined twins.
 Rare forms of conjoined twins, having different patterns:
 Parasitic twins: Asymmetrical conjoined twins, one
twin being small, less formed, and dependent upon the
other.
 Fetus in fetu: Situation in which an imperfect fetus is
contained completely within the body of its sibling.

30.  Conjunctions always involving the umbilicus:
 Thoracopagus: Anterior union of the upper half of the trunk. The
most common form of conjoined twins (about 35%), it always
involves sharing the heart.
 Cephalopagus: Anterior union of the upper half of the body with
two faces on opposite sides of a conjoined head. Extremely rare. The
heart is sometimes involved. A combination of types 3 and 4 is
called cephalothoracopagus.
 Parapagus:(sometimes balled diprosopus): lateral union of the
lower half, extending variable distances upward, about 5% of all
conjoined twins. Heart sometimes involved.
 Ischopagus: Anterior union of the lower half of the body, about 6%
of all conjoined twins. Heart not involved.
 Omphalopagus: Anterior union of the midtrunk, about 30% of
conjoined twins.

31.  Female siblings seem to have a better shot at
survival than their male counterparts.
 Although more male twins conjoin in the womb
than female twins, females are three times as likely
as males to be born alive.
 Approximately 70 percent of all conjoined twins
are girls.
 Overall female conjoint twins 3 to 10 times more
common than male conjoint twins. Why??
University of Maryland Medical centre website.

32.  Early as the 12th week of gestation on prenatal USG
 Suspicious features
 Lack of a separating membrane between the twins
 Iinability to separate fetal bodies and skin contours
 Constant position of the fetal heads.
 USG ,ECHO- at 18 to 20 weeks - anatomy of the shared organs,
associated anomalies, and
cardiac status
 Serial scans  to accurately define the extent and nature of the
union using CT and 3-dimensional volume rendering or ultrafast
magnetic resonance imaging
 Monitor for polyhydramnios or hydrops, (50% of cases)*
*Spielmann AL MRI of conjoined twins J Comput Assist Tomogr. 2001

35.  Polyhydraminos (50%)
 Requiring amnioreduction
 Conjoint twins are at a risk for significant congenital
anamolies. Look for them actively.
 Numerous case reports where such anamolies were
picked up early and pregnancy terminated
 Expect difficulties in delivery and resuscitation
 Based on the type of conjoint twins, the pediatric
surgeon must have a fair idea of the organs they are
likely to share

38.  Prenatal MRI
 Exact details of organ sharing
 Planning EXIT procedure / immediate separation
 Elective Cesarean section close to term
 Experienced team of Obstetricians, Neonatologists,
Anesthetists, Cardiologists, CTV surgeons and
Pediatric surgeons
 Full team effort with co-ordination

39.  EXIT procedure (Ex-utero Intrapartum Treatment)
 Difficulty in Airway management
 Problems with providing positive pressure ventilation
 B&T superior to B&M
 All drugs to be calculated on combined weight (100%
conjoint twins share circulation*. So ??) Index case did
not share circulation.
Remember: If one of them dies, the only way to save the other is
*
to separate them immediately.

40.  Management  Prenatal & Postnatal
 Prenatal:
 Elective termination is recommended where there is cardiac
or cerebral fusion. (Only 2 successful separations of conjoined
hearts)
 Elective interruption of the pregnancy particularly when the
anticipated severity of deformity following separation would
be unacceptable
 Postnatal: Emergent separation Vs Elective separation
 Absolute indication for emergent separation
 Death of one of the twins
 One twin has a major anamoly incompatible with life
 Elective:
 2 to 4 months of age
 Advantages

41.  Choice of imaging study will depend on the area of union.
 For thoraco-omphalopagus twins:
 Essential investigations – ECHO, CT & MRI.
 Where the livers are fused, it is important to document the
presence of separate gall bladders and hepatic veins.
 Not possible to define biliary anatomy before separation and
this should be addressed during the procedure.
 Gastrointestinal contrast studies and angiography have not
been helpful.

42.  Two sets of anesthesiologists
 Essential monitoring - arterial and central venous
catheters, electrocardiogram, pulse oximetry, capnography,
and urinary output.
 Regular blood gas analyses to be undertaken throughout
the procedure.
 All drugs and intravenous fluids calculated on a total
weight basis
 cross-circulation  drugs given intravenously have an
unpredictable effect.
 Particular care is essential when administering drugs such
as opioids, which should be given incrementally.

43.  ‘Swab technique’ ?!
 As per plan: based on imaging investigations
 Unexpected findings are not uncommon and the operative
plan may have to be varied accordingly
 Assignment of organs, such as intestine, will be equal
unless 1 twin is nonviable.
 In ischiopagus, parapagus, and pygopagus twins, urological
anatomy is often complex with 1 ureter from each twin
frequently crossing to enter the contralateral bladder.

45. Type Degree of fusion Separability
I No significant fusion Easy
II Fusion of the great vessels Easy
III Atrial fusion Possible
IIIa Mirror image right atrial Possible
fusion
IIIb Other type of atrial fusion Possible
IV Atrioventricular fusion Not possible
V Single heart in one of the Not possible
twins

46.  Following prolonged operative procedures, it is necessary
to electively paralyze and mechanically ventilate the infants
for 48 to 72 hours postoperatively.
 The infants require meticulous monitoring in the intensive
care unit, paying particular attention to cardiac
underperformance (poor cardiac output).
 Fluid and electrolyte replacement should be accurately
administered as there will be huge losses when large
prosthetic closure has been used.
 Strict infectious precautions must be exercised to avoid
sepsis, particularly where there are large skin defects.

47.  Survival rare when there is cardiac or cerebral fusion
 One case series of conjoint twins:
 28% died in utero
 54% died immediately after birth
 18% survived
 Hoyle et al analyzed all attempts at surgical separation
until 1987 and found:
 Surgical separation attempted on 167 occasions
 Overall survival – 64%
 Mortality among various subgroups: Thoraco (51%), cranio
(48%) and omphalo (32%). Mortality with ischio (19%) and
pyo (23%) was lower.
 Mortality 70% for emergent procedures and 20% for elective
Hoyle RM. Surgical separation of conjoined twins. Surg Gynecol Obstet. 1990

49. Major outcome
Spitz and Kiely. JAMA 2004

50.  Whether to sacrifice one for the other??

51. Is conjoint status more
physiological than
separation??

52. Why are there very few
reported cases of conjoined
triplets or quadruplets?

53.  Kendra and Maliyah Herrin
>>>>>
http://www.youtube.com/watch?v=5gn 2009
HTtcxoPA

54. • Loice and Christine
>>>>>
BEFORE: Two girls were
connected from the breast
bone to the navel, and shared
a liver and a main blood
vessel that connected their
hearts. 2002

55. Group member:
CHENG Tsz Yan 6S (2)
TONG Carmen 6S (23)