Understanding Your Medical Test: What It Is, How It Is Performed, and What Your Results Mean
A blood culture test checks for bacteria in your blood to diagnose infections.
{"A blood culture test detects bacteria in the blood","It helps diagnose serious infections like sepsis","Results usually take 2-5 days","Multiple blood samples may be needed for accurate results","This test identifies aerobic bacteria specifically"}
Key facts at a glance
- LOINC
- 17931-7
- Short code
- BC4ID
- Synonyms
- Bacteria Bld Aerobe Cult org #4
- Category
- chemistry
- Sample
- whole-blood
- Container
- Aerobic blood culture bottle (e.g., BacT/ALERT SA, BACTEC Plus Aerobic/F); paired with anaerobic bottle for comprehensive blood culture workup.
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- aerobic-culture
- CPT
- 87077
- SNOMED
- 442125009
- Specimen volume
- 8-10 mL per bottle for adults; 1-5 mL for pediatric patients based on weight and age; fill aerobic and anaerobic bottles according to manufacturer's specifications.
- Stability
- Blood culture bottles should be transported to the laboratory and incubated as soon as possible; bottles can generally be held at room temperature (20-25°C) for up to 2 hours prior to incubation without compromising results.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 48–120 hours
- Order
- routine
This test is a medical evaluation that helps your healthcare provider assess your overall health, screen for certain conditions, or monitor a medical problem you already have. Your provider may order it as part of a routine checkup, to look into new symptoms, or to see how well a treatment is working. Knowing the purpose of the test can help you feel more prepared and confident during your care.
A blood culture test is a laboratory test that detects bacteria in your blood. When bacteria enter your bloodstream, it can cause a serious condition called bacteremia or sepsis. This test helps doctors identify the specific type of bacteria causing the infection, which guides treatment with the right antibiotics.
How this test is performed depends on what your provider is checking, but many tests use a small sample of blood, urine, or other body material, or involve imaging equipment. A trained healthcare professional will explain each step before the test begins and answer any questions you may have. Most tests take only a short time, cause little or no discomfort, and allow you to return to your normal activities right away.
A healthcare provider will clean the skin on your arm with an antiseptic to prevent contamination. They will then draw blood from a vein, typically from your arm. Usually, two or more blood samples are taken from different veins to increase accuracy. The blood samples are placed in special culture bottles and sent to the laboratory for analysis.
Your results show whether the findings from the test fall within a range that is typical for healthy people. Normal results can be reassuring, while abnormal results do not always mean you have a serious condition and may simply call for follow-up testing. Your healthcare provider will review the results with you, explain what they mean in the context of your overall health, and discuss any next steps or treatment options with you.
A negative result means no bacteria were found in your blood samples, which is normal. A positive result indicates bacteria are present in your blood, confirming an infection. The laboratory will also identify the specific type of bacteria and perform antibiotic sensitivity testing to determine which antibiotics will be most effective for treatment.
Reference range
No growth of pathogenic bacteria; isolation of common skin contaminants such as coagulase-negative staphylococci, Corynebacterium species, or Propionibacterium species in a single blood culture bottle should be interpreted with clinical correlation and may represent contamination.N/A
Strict aseptic technique is required during blood collection to prevent contamination. Skin must be disinfected with an appropriate antiseptic (e.g., chlorhexidine or 70% isopropyl alcohol) and allowed to dry completely before venipuncture. Collection site should be away from intravenous lines whenever possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
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 the 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