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UW Health SMPH
American Family Children's Hospital

Blood Culture Volume Tables

The following tables include information on the total volume of blood to be cultured based on a patient’s weight and the distribution of blood collected for a culture.

The volume of blood drawn is the single most important factor influencing the sensitivity of blood cultures for detection of bacterial and fungal sepsis in both pediatric and adult patients. To optimize detection of organisms, 40 mL of blood should be collected per septic episode from adult patients (Table 1). Place no more than 10 mL in one bottle. For pediatric patients the amount of blood to be collected is determined by the patient's weight (Table 1), i.e., children do not have a higher bacterial load than adults (Kellogg et al, 1997).  
Total Volume to be Cultured Based on Patient Weight
Patient's weight (kg) Volume of blood to be cultured per septic episode (mL)
Less than or equal to 1.0 2.0
1.1-2.0 4.5
2.1-12.7 6.0
Special Peds*
>36.3 40.0
Except for children weighing 1.0 kg, two blood culture sets, one drawn from each of two separate sites, are needed to provide maximal information for interpretation. This is particularly important in determining whether a blood culture growing coagulase-negative Staphylococcus or Bacillus spp., for example, represents a contaminant or true bacteremia. The blood collected by the two separate draws should be distributed as follows
Distribution of Blood Collected for Culture
Patient weight (kg)   Blood culture set 1  Blood culture set 2 
    Pink (pediatric) bottle (mL)  Purple (anaerobic) bottle (mL) Pink (pediatric) bottle (mL) Purple (anaerobic) bottle (mL)
A Less than or equal to 1.0  1.5 0.5   -  -
B 1.1-2.0 1.5 1.5  1.5  -
C 2.1-12.7 1.5 3.0  1.5  
C' 12.8-20.0
Special Peds*
1.5 3.0 1.5 3.0
Weight Category Patient weight (kg) Blue (aerobic) bottle (mL) Purple (anaerobic) bottle (mL) Blue (aerobic) bottle (mL) Purple (anaerobic) bottle (mL)
D 12.8-36.3 6.5 5.0 6.5 5.0
E >36.3 10  10 10 10
*Special Peds: This designation is intended for pediatric patients whose recorded weights may not be accurate because of fluid overload, i.e., BMT, solid organ transplants, dialysis patients and ICU patients. Use ideal body weight or dry weight when calculating blood culture volumes as appropriate.
Record on each bottle the volume of blood placed in it.

Individual blood culture sets of <15 mL total volume from category E patients are suboptimal. Please call to discuss exceptions.

If only one blood culture is ordered, two will be collected from all patients except neonates <1.0 kg. A single specimen received from category B-E patients without a second specimen collected within 1 hr is suboptimal. Please call to discuss deviations from this protocol.