Twin-to-Twin Transfusion
Epidemiology and Etiology:
- Unidirectional, prenatal transfusion of blood
through arteriovenous (A-V) anastomoses in the monochorionic
twin placenta
- 5-30% of monochorionic
twins
- Acute twin-to-twin transfusion is different from
chronic twin-to-twin transfusion as described above
- Occurs to some degree in all monochorionic twins when one twin dies in utero
- The survivor experiences some degree of acute
blood loss into the dead twin’s circulation through superficial large interplacental anastomoses
Common sites:
Gross features:
- Monochorionic
twins
- Variable discrepancy in size and development of
the twins
- Particularly with respect to amniotic fluid and
fetal fluid status
- Prenatal diagnosis usually made by amniotic
fluid volume discrepancy
- Donor is pale, anemic, small
- Brain-sparing growth restriction
- Small organ weights (particularly the heart)
- Oligohydramnios
- Placental portion is remarkably pale
- Recipient is plethoric, possibly polycythemic, much larger
- Polyhydramnios
- Placental portion is congested
- Acute TTTS:
- Donor twin (smaller) may become dark, congested
- Recipient twin (larger) may be severely anemic
rather than phlethoric
Histologic features:
- Donor placenta:
- Enlarged, edematous villi
- Markedly increased nRBCs
- Recipient placenta:
- Congested villi
- Markedly increased nRBCs
Immunophenotype:
Marker:
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Sensitivity:
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Specificity:
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Molecular features:
Other features:
- Prognosis poor, especially the earlier clinical
manifestations are present
- Most often it is the donor that dies in utero,
which then leads to acute TTTS
- Acute TTTS often results in cerebral palsy
References: