Diagnosis and Staging of
  Twin to Twin Transfusion Syndrome


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    Twin Transfusion Syndrome: Also known as chorioangiopagous twins, fetofetal transfusion, twin-twin transfusion syndrome, stuck-twin syndrome, and twin oligohydramnios-polyhydramnios sequence. The syndrome appears to result from a net unbalanced flow of blood between two  fetuses through placental vascular communications. The unbalanced flow of blood shifts from one twin (the donor) to the other twin (the recipient). The donor twin develops anemia, growth restriction, and oligohydramnios; while the recipient twin develops polyhydramnios and congestive heart failure from excessive blood flow.

    Frequently Cited Ultrasonographic Criteria for Twin Transfusion Syndrome [1-6]:

      1. Same-sex twins with a single placenta.

      2. Thin (two-layer) separating membrane between the amniotic sacs. Twin peak" sign is absent.

      3. Combined polyhydramnios and oligohydramnios. Maximum vertical pocket (MVP) greater than 8 cm around recipient twin and less than 2 cm around donor fetus. The donor twin may appear "stuck" as a result of oligohydramnios.

      4. Signs of hydrops or cardiac failure in either fetus. This occurs most frequently in the larger recipient twin.

      5. Significant discrepancy in size of twins is not invariably present. When discordancy occurs the donor is the smaller twin and the recipient is the larger twin.*

    *Growth discordancy with normal fluid surrounding a normal sized twin may be also be caused by isolated growth restriction of the smaller twin. Growth discordancy with one normal sized twin surrounded by a normal amount of fluid and a larger hydropic twin may be caused immune or nonimmune hydrops in the larger twin.

    Staging of Twin-Twin Transfusion Syndrome Based on Sonographic and Doppler Findings [7].

    Poly / Oligohydramnios*
    Absent Bladder
     in Donor
    Critically Abnormal Dopplers**
    Ascites, pericardial or pleural effusion, scalp edema, or overt hydrops present.
    Demise of one or both twins.

    * Polyhydramnios: maximum vertical pocket of >8 cm; oligohydramnios: maximum vertical pocket of <2 cm.
    ** At least one of the following: a) Absent or reverse end diastolic velocity in the umbilical artery (AEDV/REDV) b) Reverse flow in the ductus venosus (RFDV), or c) Pulsatile umbilical venous flow (PUVF).


    1. Quintero RA, et al Stage-based treatment of twin-twin transfusion syndrome. Am J Obstet Gynecol. 2003;188:1333-40. MEDLINE
    2. Chitkara U and Berkowitz RL : Multiple Gestations. In: Gabbe ed: Obstetrics - Normal and Problem Pregnancies, 4th ed New York, NY, Churchill Livingstone; 2002: 842-843.
    3. D'Alton ME and Simpson LL Syndromes in twins. Semin Perinatol. 1995;19:375-86. MEDLINE
    4. Finberg HJ. The ‘twin peak’ sign: reliable evidence of dichorionic twinning.J Ultrasound Med. 1992;11:571-7.MEDLINE
    5. Bruner JP and Rosemond RL. Twin-to-twin transfusion syndrome: A subset of the twin oligohydromnios-polyhydramnios sequence. Am J Obstet Gynecol. 1993;169:925-30. MEDLINE
    6. Wittman BK, Baldwin VJ, Nichol B: Antenatal diagnosis of twin transfusion syndrome by ultrasound. Obstet Gynecol. 1981;58:123-7.MEDLINE
    7. Quintero RA, et al. Staging of twin-twin transfusion syndrome. J Perinatol. 1999;19:550-5. MEDLINE

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    Created: 1/7/2004
    Last Update: 1/7/2004