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Key Points
The twin-to-twin transfusion syndrome (TTTS) is a complication of monochorionic multiple gestations resulting from vascular communications in the placenta (chorangiopagus), such that one twin is compromised and the other is favored.
The prognosis is poor, with a perinatal mortality rate ranging from 60% to 100% for both twins.
TTTS is almost exclusively found in monochorionic twins and is estimated to occur in 5% to 15% of monochorionic twin pregnancies.
Sonographic criteria for the diagnosis of TTTS include: (1) like sex, (2) monochorionic twins, (3) polyhydramnios in one sac, oligohydramnios in the other sac with or without characteristic Doppler or echocardiographic changes.
Expectant management is not recommended due to poor perinatal outcomes associated with the disorder.
Treatment depends on the gestational age and severity at diagnosis.
Current treatment options for severe TTTS include: (1) serial reduction amniocentesis, (2) amniotic septostomy, (3) laser ablation of the anastomoses, and (4) intrafetal radiofrequency ablation.
Laser ablation appears to be a promising treatment for severe TTTS diagnosed in the midtrimester. Nonetheless, further studies are still needed to assess long-term pediatric outcome.
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The twin-to-twin transfusion syndrome (TTTS) is a complication of multiple gestation resulting from imbalanced blood flow through vascular communications in the placenta (chorangiopagus), such that one twin is compromised and the other is favored. The prognosis is poor, with a perinatal mortality rate ranging from 60% to 100% for both twins (Rausen et al., 1965; Cheschier and Seeds, 1988; Gonsoulin et al., 1990).
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The earliest description of TTTS may have been in the book of Genesis. At the birth of Esau and Jacob it was recorded that “the first one came out red,” possibly describing the birth of a polycythemic twin. In 1752, William Smellie reported the injection of the umbilical artery of one twin with the injection material flowing out of the vessel of the co-twin.
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Research in the area of vascular anastomoses in twin placenta in the late 1800s was dominated by the German obstetrician Friedreich Schatz, who described four types of vascular connections within monochorionic placentas:
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Superficial connections between capillaries.
Superficial arterial connections between large vessels.
Superficial venous connections between large vessels.
Vascular communications between capillaries in the villi.
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He described three circulatory systems in monochorionic twins. The first two were the circulations in either twin. The third circulation consisted of the arteriovenous communications bridging the two fetal circulations below the placental surface (Schatz, 1882).
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Schatz proposed that when superficial artery-to-artery and vein-to-vein anastomoses are absent or insufficient, imbalances may occur in the common circulation of the twins. Such imbalances favor the transfer of blood from one twin to the other and result in TTTS. A study demonstrating fewer anastomoses from placentas complicated by TTTS (Bajoria et al., 1995) confirms Schatz’s observations from the late 1800s. Ten ...