Purpose and Goal: CNEP # 2053

  • Understand the effects of twin-to-twin transfusion in the fetus.
  • Learn about complications of twin-to-twin transfusion in the neonate.

None of the planners, faculty or content specialists has any conflict of interest or will be presenting any off-label product use. This presentation has no commercial support or sponsorship, nor is it co-sponsored.

Requirements for Successful Completion

  • Successfully complete the post-test
  • Complete the evaluation form

Date

  • February 2017 – February 2019

Learning Objectives

  • Describe the pathogenesis of twin-to-twin transfusion.
  • Describe the fetal and neonatal risks of twin-to-twin transfusion.
  • State two approaches for the treatment of neonatal complications.

Introduction

  • Twin-to-Twin Transfusion Syndrome
    • Is also known as TTTS
  • TTTS occurs in monochorionic twin gestations
  • It is commonly identified by prenatal ultrasound
  • In most TTTS, both twins are at risk of complications
  • In severe cases, both twins are at risk of death

Twin-To-Twin Transfusion Syndrome

  • TTTS affects monochorionic (MC) twins
    • In up to 15% of twin pregnancies
    • In approximately 2,500 pregnancies/year
     
  • MC twins are identical twins
    • They share a single placenta
    • They share an unbalanced blood flow
     
  • There is an increasing incidence of TTTS
    • Due to increased IVF pregnancies
    • Due to increased multiple gestations
     
  • TTTS results from unbalanced blood flow
    • One twin receives significantly more blood flow
      • Also known as the ‘recipient’ twin
       
    • One twin receives significantly less blood flow
      • Also known as the ‘donor’ twin
       
     
  • TTTS involves inter-twin placental anastomoses
    • Anastomoses → hemodynamic shifts
    • Anastomoses may be chronic or acute
     
  • If undiagnosed, 90% of twins have long term complications
    • Especially if more than 26 weeks gestation
    • Especially if not vigorously monitored
    • Especially if not managed and treated
     
  • TTTS is generally diagnosed via prenatal ultrasound
    • Based on unequal amniotic fluid volumes
     
  • Untreated TTTS is associated with a 40-90% mortality rate

Pathogenesis of Twin-To-Twin Transfusion

  • The underlying pathophysiology of TTTS is complex
    • First identified in the 1875
    • It remains poorly understood
     
  • All MC placentas have vascular anastomoses
  • These vascular communications may be:
    • Arterio-venous (AVA)
    • Arterio-arterial (AAA)
    • Veno-venous (VVV)
     
  • AVAs are found in 95% of MC pregnancies
    • AVA flow is unidirectional
     
  • AAAs are found in 80% of MC pregnancies
    • AAA flow is bidirectional
     
  • VVVs are found in 20% of MC pregnancies
    • VVV flow is bidirectional
     
  • Advancing gestation → random vascular disruption
  • Random disruption affects vascular anastomoses
    • Potentially leading to TTTS
    • Potentially leading to unbalanced blood flow
     
  • Disrupted blood flow activates vasoactive mediators
  • Circulating vasopressors attempt to restore balance
  • In the donor twin, vasoconstriction occurs
    • Vasoconstriction leads to:
      • Hypertension
      • Hypovolemia
      • Decreased renal perfusion
      • Worsening oliguria
      • Oligohydramnios
      • Anhydramnios
      • Growth restriction
      • End organ damage
        • Cerebral infarctions
        • Renal tubular dysgenesis 
         
       
     
  • In the recipient twin, vasodilation occurs
    • Vasodilation leads to:
      •  Cardiac atrial stretch
      • Hypervolemia
      • Increased renal perfusion
      • Progressive polyuria
      • Polyhydramnios
       
     

  Diagnosis of Twin-To-Twin Transfusion

  • Early signs of TTTS may be seen in the 1st trimester
  • Most signs present in the 2nd and early 3rd trimester
  • The mother is generally asymptomatic
    • Uterine distention may be present
      • Distension → maternal discomfort
      • Distention → risk of preterm labor
       
     
  • Early ultrasound is critical to diagnosis
  • MC can be accurately determined
    • Between 11-14 weeks gestation
    • In 96-98% of all pregnancies
     
  • Diagnostic criteria for TTTS include:
    • Confirmation of MC pregnancy
    • Discordance in amniotic fluid distribution
    • Polyhydramnios in one twin
      • Max vertical pocket less than 8 cm fluid
       
    • Oligohydramnios in one twin
      • Max vertical pocket more than 2 cm fluid
       
    • Discordance in fetal bladders
      • One twin markedly enlarged
      • One twin small or nonvisible 
       
     
  • The severity of TTTS is based on Quintero staging

Quintero Staging in Diagnosing TTTS

  • Quintaro staging is used to guide diagnosis
    • Based on 2 dimensional ultrasound
    • Based on Doppler blood flow studies
     
  • The severity of TTTS is based on 5 stages:
    • Stage I TTTS
      • Oligohydramnios
      • Polyhydramnios
       
    • Stage II TTTS
      • Oligohydramnios
      • Fetal bladder nonvisible
      • Polyhydramnios
       
    • Stage III TTTS
      • Oligohydramnios
      • Polyhydramnios
      • Abnormal Doppler flow
      • Umbilical artery absent
      • Ductus venosus absent
      • Umbilical vein pulsatile flow
       
    • Stage IV TTTS
      • Fetal hydrops in one or both twins
      • With 70 - 90% risk of death
       
    • Stage V TTTS
      • Fetal death of one or both twins
       
     

Management of Twin-To-Twin Syndrome

  • Without intervention there is a 10% survival rate
    • Both twins are at risk for in utero demise
    • Recipient twins are at risk for:
      • Cardiac decompensation
      • Eventual hydrops fetalis
       
    • Donor twins are at risk for:
      • Growth restriction
      • Hypoxic-ischemic injury
       
     
  • With intervention survival improves by 50-60%
  • With intervention long term outcomes improve by 30%
  • There are two main approaches to treatment
    • Serial amnioreduction of recipient twin
      • Removal of fluid from amniotic sac
      • Involves single puncture into sac
      • Needle is guided using ultrasound
      • Improves survival rate by 37 - 60%
       
    • Amnioreduction with microseptostomy
      • Single puncture of both amnions
      • May require multiple punctures
      • Needles are guided by ultrasound
      • May increase risk of preterm labor
       
     
  • Removing excess fluid in the recipient twin
    • Reduces uterine distension
    • Improves maternal comfort
    • Is most beneficial in stages I and II
    • Decreases risk of premature rupture
    • Decreases risk of premature labor
    • Improves utero-placental perfusion
     
  • Performing microseptostomy in both twins
    • Balances intra-amniotic pressures
    • Between both donor and recipient twin
     
  • Fetal laser ablation is the definitive treatment
    • Also known as laser photocoagulation
    • Improves fetal survival in severe TTTS
      • If done between 16 - 26 weeks gestation
       
    • Markedly improves neonatal outcomes
      • Overall survival rate is 60%
       
    • Laser ablation of anastomotic vessels
      • Is beneficial in all stages
      • Is most beneficial in stages II - IV
       
    • Laser ablation is performed under anesthesia
      • As an outpatient procedure
      • May require local anesthesia
      • IV sedation most common
       
    • A fetoscope is inserted into recipient twin sac
      • Inserted with ultrasound guidance
      • Ablation of vessels is done via laser
      • It creates two independent circulatory systems
       
     
  • In severe TTTS, selective reduction may improve survival
    • With life threatening malformations
    • With severe fetal growth restriction
    • With stage IV TTTS pregnancies
     

Neonatal Outcomes in Twin-To-Twin Syndrome

  • Improved perinatal survivability → improved outcomes
  • The median age for TTTS delivery is 32 weeks gestation
  • The risks of prematurity include:
    • Hypothermia
    • Hypoglycemia
    • Respiratory distress
    • Patent ductus arteriosis
    • Chronic lung disease
    • Necrotizing enterocolitis
    • Retinopathy of prematurity
    • Intraventricular hemorrhage
     
  • Other risks of TTTS include:
    • Renal failure
    • Cardiac failure
    • Growth restriction
    • Hematological instability
    • Atypical cerebral lesions
    • Hypoxic-ischemic lesions
      • Limbs
      • Bowel
       
    • Developmental delays
    • Poor neurodevelopmental outcomes
    • In up to 11% of survivors
    • Cerebral palsy is frequently seen
     
  • Neonatal screening is recommended
    • Head ultrasound
    • Echocardiogram
     

Neonatal Complications of Donor Twins

  • Donor twins are usually smaller and anemic
  • They have smaller umbilical cords
  • They are frequently growth restricted
    • Hypoglycemia is a primary concern
     
  • They frequently require fluid resuscitation at birth
    • Increased volume to correct hypovolemia
    • Red blood cells to correct severe anemia
     
  • Positional deformations may be seen
  • Pulmonary hypoplasia may be seen (uncommon)

Neonatal Complications of Recipient Twins

  • Recipient twins are usually larger and polycythemic
  • They have larger than average
    • Umbilical cords
    • Abdominal circumferences
    • Kidneys
    • Bladders
     
  • They are generally more acutely ill at birth
  • They frequently require respiratory support at birth
  • They may require cardiovascular support as
    • They are at risk for:
      • Cardiomegaly
      • Tricuspid regurgitation
      • Ventricular hypertrophy
       
    • Inotropic support or digoxin may be needed
      • To increase contractility
      • To increase cardiac output
       
     
  • A partial exchange transfusion may be indicated
    • With severe polycythemia
    • With any symptomatic polycythemia
    • With signs of emboli due to sluggish blood
     
  • Intensive phototherapy may be indicated
    • With significant hyperbilirubinemia
     
  • Full resuscitative support may be required
    • In infants who present with hydrops fetalis
     

Summary

  • Twin gestation pregnancies are increasing in the US
  • Twin-to-twin transfusion is a serious complication
  • Successful management involves a vigilant approach
  • Early intervention is the key to optimal neonatal outcomes

References

  1. Giconi, S.S. 2013. Twin-To-Twin Transfusion Syndrome: A Case Study. Advances in Neonatal Care, 13 (1), p. 31-37
  2. Squires, L.S. 2013. A Case Study of Recipient Twin Surviving Complications of Twin-To-Twin Transfusion Syndrome. Nursing For Women’s Health, 17 (5), p. 390-398.
  3. Bliss, J.M., Carr. S.R., DePaepe, M.E. and Luks, F.I. 2017. What – and Why – the Neonatologist Should Know About Twin-To-Twin Transfusion Syndrome. NeoReviews, 18 (1), p. e22-e32.
  4. Johnson, A. & Papanna, R. 2016. Twin-To-Twin Transfusion Syndrome: Management and Outcome. Up-To-Date
  5. Papanna, R. & Johnson, A. 2016. Twin-To-Twin Transfusion Syndrome and Twin Anemia Polycythemia Sequence: Pathogenesis and Diagnosis. Up-To-Date
  6. Mandy, G.T. 2016. Neonatal Complications, Outcomes, and Management of Multiple Births. Up-To-Date
  7. Johnson, A. 2015. Diagnosis and Management of Twin-Twin Transfusion Syndrome. Clinical Obstetrics and Gynecology, 58 (3), p. 611-631.
  8. Paek, B & Shields, L.E. 2005. Twin-To-Twin Transfusion Syndrome: Diagnosis and Treatment. Current Women’s Health Reviews, 1 (1), p. 43-47.

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