section_path: Research and development/Children's Hospital of Philadelphia (USA)
section_name: Children's Hospital of Philadelphia (USA)
paragraph_text: Children's Hospital of Philadelphia (USA)
  
  In 2017, researchers at the Children's Hospital of Philadelphia were able to further develop the extra-uterine system. The study uses fetal lambs which are then placed in a plastic bag filled with artificial amniotic fluid. The system consist in 3 main components: a pumpless arteriovenous circuit, a closed sterile fluid environment and an umbilical vascular access. Regarding the pumpless arteriovenous circuit, the blood flow is driven exclusively by the fetal heart, combined with a very low resistance oxygenator to most closely mimic the normal fetal/placental circulation. The closed sterile fluid environment is important to ensure sterility. Scientists developed a technique for umbilical cord vessel cannulation that maintains a length of native umbilical cord (5–10 cm) between the cannula tips and the abdominal wall, to minimize decannulation events and the risk of mechanical obstruction. The umbilical cord of the lambs are attached to a machine outside of the bag designed to act like a placenta and provide oxygen and nutrients and also remove any waste. The researchers kept the machine "in a dark, warm room where researchers can play the sounds of the mother's heart for the lamb fetus." The system succeeded in helping the premature lamb fetuses develop normally for a month. Indeed, scientists have run 8 lambs with maintenance of stable levels of circuit flow equivalent to the normal flow to the placenta. Specifically, they have run 5 fetuses from 105 to 108 days of gestation for 25–28 days, and 3 fetuses from 115 to 120 days of gestation for 20–28 days. The longest runs were terminated at 28 days due to animal protocol limitations rather than any instability, suggesting that support of these early gestational animals could be maintained beyond 4 weeks. Alan Flake, a fetal surgeon at the Children's Hospital of Philadelphia hopes to move testing to premature human fetuses, but this could take anywhere from three to five years to become a reality. Flake, who led the study, calls the possibility of their technology recreating a full pregnancy a "pipe dream at this point" and does not personally intend to create the technology to do so.