Understanding Your Medical Test: What It Is, How It's Done, and What to Expect
A blood culture test detects bacteria or fungi in your blood, helping doctors diagnose serious infections like sepsis or bacteremia.
{"A blood culture test checks if bacteria or fungi are growing in your blood","It helps diagnose serious bloodstream infections and guides antibiotic treatment","Multiple blood samples are usually collected from different veins to improve accuracy","Results typically take 2-5 days as the lab needs time to grow and identify microorganisms","Positive results mean you have a bloodstream infection that requires treatment"}
Key facts at a glance
- LOINC
- 48724-9
- Short code
- BCID3
- Synonyms
- Bacteria Bld Cult org #3
- Category
- chemistry
- Sample
- whole-blood
- Container
- Aerobic and anaerobic blood culture bottles (e.g., BACTEC Plus Aerobic/F, BACTEC Plus Anaerobic/F, BacT/ALERT FA/FN Plus). Pediatric bottle (Peds Plus) may be used for smaller volumes.
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- culture
- CPT
- 87040-87077
- SNOMED
- 104236004
- Specimen volume
- Adult: 8-10 mL per bottle (20-30 mL total for aerobic and anaerobic set). Pediatric: 1-5 mL per bottle based on weight. Optimal blood-to-broth ratio is approximately 1:5 to 1:10.
- Stability
- Inoculated bottles should be transported to the laboratory at room temperature (20-25°C) within 2 hours of collection. Do not refrigerate. Bottles may be held in monitored incubators for up to 5 days. If delayed transport is necessary, hold at room temperature; do not incubate or refrigerate.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 24–120 hours
- Order
- routine
What is this test, what does it measure or check for, and why might my healthcare provider recommend it for me?
A blood culture test is a laboratory test that detects bacteria or fungi in your blood. When microorganisms grow in the culture bottles over time, they are identified, and antibiotic sensitivity testing may be performed to determine which treatments will work best. This test is crucial for diagnosing bloodstream infections, including sepsis, which is a life-threatening condition.
How is the test performed, how should I prepare for it, and will I need to do anything special before my appointment?
A healthcare professional will clean your arm with an antiseptic and draw blood from a vein, usually in your arm. Typically, two or more blood samples are collected from different sites to reduce the chance of contamination and improve accuracy. The blood is then placed in special culture bottles that contain nutrients to help any bacteria or fungi grow. These bottles are incubated and monitored for several days.
What happens during the test from start to finish, how long does it usually take, and will it be painful or uncomfortable?
The test involves having blood drawn, similar to a routine blood test. You may feel a brief pinch or mild discomfort when the needle is inserted. The procedure usually takes only a few minutes. After the blood is collected, there are no additional immediate steps required from you. The laboratory will handle the culture process, which requires time for any present microorganisms to grow and be identified.
Are there any risks, side effects, or complications associated with this test, and when should I contact my doctor afterward?
The risks are minimal and similar to routine blood draws. You may experience slight bruising, bleeding, or soreness at the puncture site. In rare cases, fainting or infection may occur. The benefits of diagnosing a serious infection far outweigh these minor risks. If you have bleeding disorders or are on blood thinners, inform your healthcare provider before the test.
Reference range
No growth (Negative). Blood cultures are normally sterile; identification of organism is reported qualitatively (e.g., Staphylococcus aureus, Escherichia coli).N/A
No fasting required. Strict aseptic skin preparation with chlorhexidine or povidone-iodine is essential. Disinfect blood culture bottle tops before inoculation. If patient is on antibiotics, note the antibiotic regimen and consider collecting blood cultures prior to next dose when possible. Disinfect venipuncture site thoroughly to minimize contamination with skin flora.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
Why do I need multiple blood samples?
How long does it take to get results?
What does a positive result mean?
Does a negative result mean I don't have an infection?
Do I need to fast before this test?
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