Compared to standard component therapy, fresh whole blood (FWB) offers potential benefits to neonates undergoing cardiopulmonary bypass (CPB) in the context of open cardiac surgery: decreased blood loss and subsequent risk of volume overload, improved coagulation status, higher platelet counts during and following CPB, circumvention of limited vascular access, and significantly reduced donor exposures. Obtaining FWB, however, entails 2-5 days of preparation, which often precludes its availability for neonates requiring CPB in the immediate newborn period. Using a multidisciplinary approach and molecular ABO/RHD genotyping on amniotic fluid, we developed a protocol to allow procurement of FWB for timed delivery followed by open cardiac surgery. Eligible subjects include patients undergoing genetic amniocentesis following the diagnosis of a fetal cardiac anomaly likely to require open surgical repair in the initial days after birth. This protocol has been successfully implemented following prenatal diagnosis of severe fetal cardiac anomalies. Taking advantage of the prenatal time period and the ability to perform fetal blood typing prenatally using molecular genotyping makes possible a new paradigm for the availability of FWB for CPB to improve perioperative, short-term, and long-term outcomes in a population comprised of some of the smallest and sickest patients who will undergo CPB.