Fetal Medicine Centre

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TRAP sequence by G. S. JACK22/02/2007

• Fetal Medicine Centre
• Chris Hani Baragwanath Hospital
• University of the Witwatersrand

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• PATIENT NAME - L.V.
• AGE 20 YEAR OLD (
  MOZAMBICAN)
• SOCIAL HISTORY - P.1 G.2
• - Nonsmoker
• - No alcohol
• - Unemployed
• - Has twin
  sisters
• - No congenital
• abnormalities
  in her family

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• CLINICAL HISTORY - RH
• - No diabetes
• - Retro-
  negative
• - No treatment

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• REFERED to CHBH on 06/09/2006 from
• Stretford clinic ( Orange Farm)
• for discrepancy between dates
• HOF.
• Dates 24 wks, HOF 36cm.

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• ULTRASOUND FINDINGS
• Twin pregnancy noted
• 1st Twin- cephalic presentation
• Anterior single placenta
• Av. GA 24 wks 2d
• EFW 688g
• Amniotic fluid normal
• Doppler RI 0,64 (n)
• Gender XY
• No obvious abnormalities noted.
• Separating membrane noted.
• Diamniotic/monochorionic twins.

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• TWIN 2
• - Polyhydramnios noted.
• - This twin appeared to be an ACARDIAC/TRAP
• sequence.
• Very small underdeveloped spine( vertebral
• column) noted.
• No obvious fetal head noted.
• No obvious heart noted.
• No obvious chest lungs noted.
• No obvious abdomen abdominal organs noted.

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• -There is a soft tissue mass containing small
  vertebral column two lower limbs arising from
  this mass.
• -There are two main vessels noted running through
  this mass from umbilical cord.
• -Surrounding soft tissue is edematous .
• -There is a cystic structure noted within the
  soft tissue at the mid lower back.
• -Two lower limbs noted arising from this mass.
• -Right leg- longer than left one.
• -Rt femur 19 wks. Short tib/fib with ? Club
  foot.
• -Left leg- short femur. Only tibia ? Fractured,
  noted with foot attached to it, Foot also ?
  Clubbed.
• PLAN Booked for FAC 12/09/2006.

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• FAC REPORT 12/09/2006
• -Confirmed twin pregnancy
• -Diamniotic/monochorionic
• TWIN 1
• -Cephalic lie
• -AV, GA26wks
• -EFW 1031g
• -AFI-normal
• -Normal dopplers
• -No structural abnormalities noted
• TWIN 2 ACARDIAC
• -PLAN-Rescan at 30wks-10/10/2006

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• FAC REVIEW 10/10/2006
• TWIN 1
• -GA30wks-Normal fetal growth
• -EFW1369g
• -AFI-normal
• -Dopplers-normal
• TWIN 2
• AFI -Polyhydramnios
• EFW- less than 50 of twin 1
• -Assessment- situation is haemodynamically stable
  with cervical length of 36mm
• -PLAN-In absence of cardiac failure in the pump
  twin, there is no indication for delivery at this
  stage.
• -Rescan in two weeks time.

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• RESCAN 01/11/2006
• TWIN 1
• -Cephalic
• -GA32wks 3d
• -EFW2015g
• -AFI-normal
• -Doppler RI0.60-normal
• TWIN2
• -Polyhydramnios
• -Appeared to be bigger than twin 1
• -AC is above 42wks
• -Cervical length27mm,os closed
• -FAC ?03/11/2006

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• FAC REPORT 03/11/2006
• -GA33wks 4d
• -EFW2222g
• -AFInormal
• -Dopplers-umbilical artery ductus venosus PI
  high.
• -PLAN-In view of good fetal weight of pump twin,
  we advise admission for administration of
  Celestone for fetal lung maturity and delivery by
  Caesarian section over this weekend.

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ULTRASOUND PICTURES
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• Patient admitted 3/11/2006
• C/S 06/11/2006
• Caesarian section-Twin 1 cephalic-normal, xy.
• Twin 2-Acardiac-delivered with difficulty. Also
  xy.
• Polyhydramnios
• Otherwise uneventful C/S
• Birth weight ?Twin 1-normal 2040g
• ? Twin 2-Acardic 1530g
• Patient discharged 10/11/2006

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POST NATAL PHOTOS
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(No Transcript)
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X-RAYS OF ACARDIAC FETUS
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THREE MONTHS LATER-16/02/2007
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WHAT IS TRAP sequence?
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• TRAP Twin reversed arterial perfusion
• syndrome.
• -Synonyms-acardius or chorioangopagus
  parasiticus.
• -Definition Complication of monozygotic twin
  pregnancy in which one fetus develops normally (
  pump twin) and the second twin ( recipient twin)
  demonstrate cardiac maldevelopment ranging from
  complete absence of heart tissue to some
  formation of rudimentary myocardia.
• -It can be classified into two main groups
• -1st group -hemiacardius imperfectly formed
  heart.
• -2nd group holoacardius absence of heart.

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• It is subdivided into four groups based on the
  degree of cephalic and truncal maldevelopment.
• 1.Acardius acephalus-absence of head.
• 2.Acardius anceps/paracephalus-some cranial
  structures and or neural tissue present.
• 3.Acardius acormus-only head present.
• 4.Acardius armophus/anideus-no discernible
  cephalic or truncal structures.

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• Etiology-Probable reversal of circulation in the
  abnormal twin resulting from anastomosis of
  circulation between the twins.
• Incidence-1 in 35,000 births,1monochorionic twin
  pregnancies ( United States New York City).
• Sonographic findings useful in the diagnosis of
  acardia
• Absence of normal cardiac structure, presence
  of limb movements and variable structural
  abnormalities.
• Common structural abnormalities- anencephaly,
  exomphalos and absence of upper limbs.

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• Sonographic findings continuation
• Edematous soft tissue, large cystic hygroma- like
  spaces in the skin, monochorionic/diamniotic (
  74).
• Monoamniotic ( 24) cases.
• Two vessel cord and polyhydramnios.

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• Differential diagnosis
• Twins with 1 IUFD, Anencephalic twin, cystic
  hygromas, singleton with intraamniotic tumours
  and pseudo acardiac twin.
• Prognosis- Lethal for the recipient twin and 50
  mortality rate in pump twin.
• Recurrence risk not increased.
• Management- serial ultrasound for evaluation of
  growth and signs of CCF in the pump twin.
• Karyotype normal twin.

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• Management cont.
• To predict the outcome of the pregnancy, the
  weights of the twins were expressed as a ratio
  called Twin Weight Ratio ( TWR).
• TWR-is the wet weight of the acardiac twin
  divided by the weight of the normal twin.
• TWR above 70 results to polyhydramnios, preterm
  delivery and CCF in the pump twin.
• This data aid in counseling and management of
  patient.

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TREATMENT/INTERVENTIONAL PROCEDURE
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• Treatment/ Interventional procedures
• -Interruption of the circulation to the abnormal
  twin is suggested to improve outcome in high risk
  cases.
• -It is suggested that termination of the
  circulation to the abnormal twin may reduce
  amount of polyhydramnios and subsequently prolong
  the pregnancy.
• -Selective delivery by hysterotomy of an
  acardiac twin at 22wks GA with subsequent
  delivery of normal twin at 33wks.

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• Treatment/Intervention continuation
• Selective delivery- one case reported placental
  abruption after the procedure resulting to fetal
  demise of a normal twin.
• Selective fetocide was suggested, but injection
  of a lethal substance would also endanger normal
  twin.
• Insertion of a helical metal coil under
  sonographic guidance to induce thrombosis in the
  umbilical artery of an acardiac twin at 24wks.Co
  twin delivered at 39wks.
• Percutaneous fetoscopic procedure at 19wks,
  normal twin born at 36wks.

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• Treatment/Intervention continuation
• Injection of multiple pieces of silk suture
  soaked in 96 alcohol into the umbilical cord of
  an acardiac twin at 21wks, normal twin delivered
  at term 2730g and healthy.
• -Advantage of this approach compared to
  umbilical- cord ligation is the use of a much
  thinner needle, less operative time required and
  no need for GA.
• Conclusion- Pump twin remains at high risk of
  sudden death even without sonographic features of
  cardiac failure, possibly due to acute
  disseminated intravascular coagulation.

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• References
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• 2. Benirschke K, Harper VDS. The acardiac
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• 3. Moore TR, Gale S, Benirschke K. Perinatal
  outcome of forty-nine pregnancies complicated by
  acardiac twinning. Am J Obstet Gynecol
  163907-912, 1990
• 4. Romero R, Pilu G, Jeanty P, Ghidini A, Hobbins
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• 5. Seeds JW, Herbert WNP, Richards DS. Prenatal
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• 6. Van Groeninghen JC, Franssen AMHW, Willemsen
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• 7. Sherer DM, Armstrong B, Shah YG, Metlay LA,
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  subsequent management of an acardiac twin
  pregnancy. Obstet Gynecol 74472-475, 1989
• 8. Platt LD, De Vore GR, Bieniarz A, Benner P,
  Rao R. Antenatal diagnosis of acephalus acardia
  a proposed management scheme. Am J Obstet Gynecol
  143857-859, 1983
• 9. Stiller RJ, Romero R, Pace S, Hobbins JC.
  Prenatal identification of twin reversed arteral
  perfusion syndrome in the first trimester. Am J
  Obstet Gynecol 1601194-1196, 1989
• 10. Fusi L, Fisk N, Talbert D et al. When does
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  diagnostic difficulties. J Perinat Med. 18
  223-7, 1990
• 11. Hamada H, Okane M, Koresawa M et al. Fetal
  therapy in utero by blockage of the umbilical
  blood flow of acardiac monster in twin pregnancy.
  Nippon Sanka Fujinka Gakkai Zasshi 41 1803-9,
  1989

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• THANK YOU!