Red blood cell the centre of 0.8–1 µm, being much smaller than most other human cells. These cells have an average volume of about 90 fL with a surface of about 136 μm, and can swell up to a sphere shape containing 150 fL, without membrane distension. Adult humans have roughly 20–30 trillion red blood cells at any given time, constituting approximately 70% of all cells by number. Women have about 4–5 million red blood cells per microliter (cubic millimeter) of blood and men about 5–6 million; people living at high altitudes with low oxygen tension will have more. Red blood cells are
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