Understanding Your Laboratory Test: What It Is, How It Is Done, and What Your Results Mean
A blood culture test detects bacteria in your blood to help diagnose infections.
{"This test looks for harmful bacteria in your blood","It helps doctors diagnose bloodstream infections","Results usually take 2-5 days","A small blood sample is drawn from a vein"}
Key facts at a glance
- LOINC
- 45275-5
- Short code
- BLDCUL25
- Synonyms
- Bacteria Bld Aerobe Cult 25 Deg
- Category
- chemistry
- Sample
- whole-blood
- Container
- Aerobic blood culture bottle (e.g., BacT/ALERT SA, BACTEC Plus Aerobic/F). For pediatric or low-volume collections, pediatric aerobic bottles may be used. Sterile collection set with butterfly needle or syringe.
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- aerobic-culture-deg-c-incubation
- CPT
- 87040
- SNOMED
- 104241003
- Specimen volume
- Adult: 8-10 mL per aerobic bottle (20-30 mL total blood per set recommended for sepsis evaluation). Pediatric: 1-5 mL per bottle based on patient weight (age and weight-based protocols).
- Stability
- Inoculated bottles should be transported to the laboratory as soon as possible. Hold at room temperature (20-25°C) or per manufacturer instructions. Do not refrigerate. Delayed transport may compromise organism recovery. Bottles should be loaded into continuous-monitoring blood culture instruments within 2 hours of collection when feasible.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 48–120 hours
- Order
- routine
What is this test, and what does it check or measure in my body?
A blood culture test is a laboratory test that checks for bacteria or other germs in a blood sample. Your blood is normally sterile, meaning it should not contain any microorganisms. When bacteria are found in the blood, it indicates a serious infection called bacteremia or septicemia.
How is this test performed, and what can I expect during the procedure?
A healthcare provider will clean the skin on your arm with an antiseptic solution to prevent contamination. Then, they will draw a small amount of blood from a vein, typically from your arm. The blood sample is placed in special culture bottles and sent to the laboratory for analysis. The sample is incubated at 25 degrees Celsius (77 degrees Fahrenheit) to help grow and identify aerobic bacteria.
Why might my doctor recommend this test for me?
Your doctor may order a blood culture test if you have symptoms of a bloodstream infection, such as fever, chills, rapid breathing, fast heart rate, or confusion. It is also used to monitor patients with certain conditions, those recovering from surgery, or people with weakened immune systems.
What do my test results mean, and how should I discuss them with my doctor?
A 'negative' result means no bacteria were found in your blood culture, which is normal. A 'positive' result means bacteria were detected, indicating a bloodstream infection. The laboratory will also identify the specific type of bacteria found, which helps your doctor choose the most effective treatment, such as specific antibiotics.
Reference range
No growth of clinically significant bacteria. Reportable: organism identification with genus and species when recovered (e.g., Pseudomonas spp., Acinetobacter spp., Staphylococcus spp., Corynebacterium spp., Bacillus spp., and other environmental/environmental opportunistic bacteria).N/A
Standard aseptic venipuncture technique is required. Skin preparation with chlorhexidine or 70% isopropyl alcohol followed by povidone-iodine (or equivalent) is mandatory to reduce contamination. Disinfect blood culture bottle tops prior to inoculation. Collect prior to starting antibiotics whenever possible to maximize recovery. No fasting required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Blood culture testing is essential for diagnosing bacteremia (bacteria in the blood) and sepsis (a life-threatening response to infection). Early detection of bloodstream infections allows for prompt antibiotic treatment, which can be lifesaving. The test also helps identify the specific bacteria causing the infection, enabling doctors to select targeted antibiotics rather than broad-spectrum treatments, which helps combat antibiotic resistance.
Frequently asked questions
Does the test hurt?
How long does it take to get results?
Do I need to fast before this test?
What happens if my test is positive?
Sources
- 1
- 2
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy