The Effect of Uterine Entry In Fetoscopic Laser Photocoagulation for Twin-To-Twin Transfusion Syndrome

Inclusion Criteria: * Patients who are eligible and elect to undergo fetoscopic selective laser photocoagulation for complicated monochorionic-diamniotic twin pregnancies with twin-to-twin transfusion syndrome. * Patients will be between 16 0/7 weeks and 26 0/7 weeks gestational age. Exclusion Criteria: * Patients who do not elect to undergo fetoscopic laser photocoagulation for the treatment of complicated monochorionic-diamniotic twin pregnancies with twin-to-twin transfusion syndrome. * Triplets and higher order multiple gestations. * Patients who are less than 16 0/7 weeks or greater than 26 0/7 weeks gestational age. * Patients with a short cervix (less than 1.5 cm). * Patients with a known subchorionic hemorrhage.