Fetal endoscopic surgery has progressed rapidly over the past decades and the investigators are now able to perform a number of intricate procedures inside the uterus with specially designed instruments. These procedures include laser therapy for Twin-twin-transfusion syndrome, fetal cystoscopy and fulguration of posterior urethral valves, release of amniotic bands, and placement of various shunts and balloons inside fetal structures and cavities (peritoneal, pleural, cardiac, and trachea).