Red blood cell being dissolved in body fluid) was an important step in the evolution of vertebrates as it allows for less viscous blood, higher concentrations of oxygen, and better diffusion of oxygen from the blood to the tissues. The size of red blood cells varies widely among vertebrate species; red blood cell width is on average about 25% larger than capillary diameter, and it has been hypothesized that this improves the oxygen transfer from red blood cells to tissues. The red blood cells of mammals are typically shaped as biconcave disks: flattened and depressed in the center, with a dumbbell-shaped cross section,
Neonatal red cell transfusion baby (e.g. wristband). Paedipacks are multiple aliquots made from one adult blood donation. By using paedipacks, the baby is exposed to blood from fewer blood donors. ABO blood grouping and screening for antibodies in neonates differs from blood grouping in adults and older children. Any antibodies detected are the mother's antibodies rather than the baby's. Therefore, any donor blood given to the baby must be ABO and D compatible with both mother and baby; and antigen-negative for any clinically significant maternal antibodies. Necrotising enterocolitis may occur after a red cell transfusion in neonates, although there is an association between the