A 24‑week pregnant woman fears for her unborn baby, who is developing with a sacrococcygeal teratoma so large and vascularized that it nearly surpasses the size of the fetus itself. Faced with this threat, surgeons operate inside the uterus in an open procedure that partially exposes the baby to remove the tumor and give the baby a chance to survive until birth. According to scientists presenting at the American Society of Gene & Cell Therapy's special meeting on Breakthroughs in Targeted In Vivo Gene Editing, this could be avoided.