Twin-twin transfusion syndrome leads to high rates of perinatal morbidity a
nd mortality due to its poorly understood etiology and difficult diagnosing
and treatment. Current therapies are suboptimal and have not been tested t
hrough randomized controlled trials. Parent counseling at the time of diagn
osis includes informing on poor chance of double survival, relatively high
chance of long term neurologic handicap, the near certainty of prematurity,
and the probability of cesarean delivery. Improvement in therapies awaits
a better scientific understanding of the etiology of this condition.