How much blood should be drawn at any one time from a 7-lb baby?

How much blood should be drawn at any one time from a 7-lb baby?

• A. No more than 2.5 mL
• B. No more than 10 mL
• C. No more than 20 mL
• D. No more than 1.0 mL

Answer: (D)

The important idea is safety in pediatric phlebotomy: newborns have a very small total blood volume, so any single blood draw must be kept to a tiny amount to avoid compromising circulation. A baby weighing about 7 pounds (roughly 3.2 kg) typically has a total blood volume of around 85 mL per kg, which is about 270 mL in this case. Limiting the volume drawn at one time to about 1 mL keeps the percent of total blood volume removed very small (well under 1%), reducing the risk of hypovolemia or anemia while still allowing necessary testing. Larger single-draw volumes, such as 2.5, 10, or 20 mL, would remove a much more substantial portion of the baby’s blood and could be dangerous, especially if multiple samples are needed. Therefore, the best practice is to draw no more than 1.0 mL at a time.

The important idea is safety in pediatric phlebotomy: newborns have a very small total blood volume, so any single blood draw must be kept to a tiny amount to avoid compromising circulation. A baby weighing about 7 pounds (roughly 3.2 kg) typically has a total blood volume of around 85 mL per kg, which is about 270 mL in this case. Limiting the volume drawn at one time to about 1 mL keeps the percent of total blood volume removed very small (well under 1%), reducing the risk of hypovolemia or anemia while still allowing necessary testing. Larger single-draw volumes, such as 2.5, 10, or 20 mL, would remove a much more substantial portion of the baby’s blood and could be dangerous, especially if multiple samples are needed. Therefore, the best practice is to draw no more than 1.0 mL at a time.