Sepsis Testing Timelines: How Long Does a Sepsis Test Take?

Sepsis demands the same urgency as a heart attack or stroke—every minute counts as rapid diagnosis and treatment significantly increase the chances of survival. Traditional lab tests for sepsis can vary dramatically in turnaround times, and the challenge lies in choosing a diagnostic tool that can reliably detect sepsis quickly enough to guide effective care decisions for patients who are truly septic, while avoiding overtreatment in those who are not.

This article examines how long commonly used sepsis tests typically take to deliver results. We’ll discuss timelines and how the insights from each test impact clinical decision making, and explore how newer, rapid diagnostic tools like the IntelliSep test may support a more timely, accurate sepsis diagnosis.

How Long Does a Sepsis Test Take? – (Time on Machine)

• Procalcitonin Test: 18-25 minutes : The procalcitonin (PCT) test is a commonly used blood test for bacteremia. Under normal conditions, procalcitonin is produced at very low levels. However, in the presence of a serious bacterial infection, cells throughout the body release procalcitonin into the bloodstream. This surge in procalcitonin results in elevated levels that can indicate a significant bacterial infection often associated with sepsis. While the PCT test is widely used as a biomarker to support clinical decision-making, it is limited in that it does not support sepsis detection due to non-bacterial infections. The total turnaround time for a procalcitonin test is typically around one hour, though this can vary depending on the hospital’s laboratory processes and workflows. While serving as a useful datapoint, this delay can impact the speed at which clinicians are able to make treatment decisions — a critical consideration when managing a time-sensitive condition like sepsis.²
• Lactate or Lactic Acid Test: 10 minutes: Elevated lactate levels can indicate impaired oxygen delivery and tissue hypoperfusion and may signal a wide range of medical conditions, including sepsis.^3,4 Under normal circumstances, cells rely on oxygen to break down food for energy; however, in oxygen-deprived states—as can occur in sepsis and other critical conditions—cells switch to anaerobic metabolism, resulting in the production of lactate in the muscles and red blood cells. The liver and kidneys typically convert this lactate back into glucose for energy use.
  
  In the context of sepsis, elevated lactate is often used as a marker of tissue hypoperfusion and severity of illness, helping clinicians assess the urgency of intervention. Lactate levels are not only used for identification and risk stratification but also for monitoring treatment response. When lactate levels decrease over time, it often indicates that tissue perfusion is improving, and the patient is responding to therapy. ^3,4
  
  The typical total turnaround time for a lactate test is approximately 45 minutes, though this can vary depending on laboratory workflows and hospital protocols.^3,4
• Blood Cultures: 24 to 48-hours: A blood culture is a laboratory test used to detect bacteria or other pathogens in a blood sample. The sample is cultured in a specialized medium, and the lab monitors it for evidence of microorganism growth. In some cases, a Gram stain is performed to identify the bacteria using a series of chemical stains. Since certain infections can cause bacteria to appear intermittently in the bloodstream, multiple blood cultures—typically three or more—may be required to improve the likelihood of detecting the infection.^5,6
  
  The total turnaround time for blood cultures can vary widely, but it generally takes about 24 to 48 hours to identify bacterial growth. While blood cultures are essential for confirming the presence of a bloodstream infection, their relatively slow turnaround time means they are typically not useful for the rapid identification of sepsis, nor can they identify non-bacterial causes of sepsis. Additionally , the high frequency of blood culture contamination rates and false positives can further delay appropriate treatment. Notably, 28%-49% of sepsis cases are blood culture-negative, yet these patients experience similar outcomes to those with positive cultures.⁹ As a result, clinicians often rely on faster diagnostic tests to guide initial treatment decisions while awaiting blood culture results.^5,6
• IntelliSep Host Response Test: ~8 minutes: The IntelliSep test directly measures the immune dysregulation that defines sepsis by analyzing biophysical changes that occur in white blood cells early in the immune response to infection. Using advanced microfluidics and deformability cytometry, the Cytovale System interrogates tens of thousands of white blood cells, observing subtle changes in their biomechanical properties. The system then applies high-throughput image analysis combined with machine learning to evaluate biologically relevant features in each cell image. These insights are translated into a single score that reflects the patient’s probability of sepsis. The IntelliSep test delivers this sepsis risk score within 8 minutes – often made available to the provider alongside the stat order set – empowering clinicians to make timely, confident decisions at the most critical intervention point. ⁷

Why is Early Sepsis Detection Critical?

Sepsis is a rapidly progressing, life-threatening condition caused by the body’s dysregulated immune response to infection. The longer sepsis goes undetected and untreated, the greater the risk of organ failure, septic shock, and death. Patients diagnosed with severe sepsis have up to a 30% mortality rate. Studies have shown that with each hour of delay in recognizing and treating sepsis, mortality rates increase. Early detection allows clinicians to intervene with targeted treatments — such as antibiotics, fluids, and supportive care — before irreversible damage occurs. In short, timely sepsis diagnosis not only saves lives but also reduces complications, shortens hospital stays, and lowers overall healthcare costs.^1,8

Accurate Early Sepsis Detection with IntelliSep

IntelliSep serves as a valuable adjunct in the early identification of sepsis. Its key advantage lies in its rapid turnaround time — providing results within 8 minutes — and its strong clinical performance, with a 98% negative predictive value (NPV) for Band 1 patients, representing a low probability of sepsis.1,9 For those Band 1 patients, this rapid, accurate risk stratification enables clinicians to confidently rule out sepsis as the likely diagnosis and investigate alternative causes for the patient’s symptoms. While alternatively, in Band 3 patients where sepsis is highly probable, clinicians are able to immediately administer broad spectrum antibiotics and disposition the patient according to the care needed. Additionally, IntelliSep helps address a significant challenge in sepsis care: the high rate of false positives from traditional screening tools, which can lead to overtreatment. By providing more accurate and timely risk stratification, IntelliSep empowers clinicians to make more precise, confident treatment decisions.^1,9

References

1. Singer M, Deutschman CS, Seymour CW, et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA. 2016;315(8):801–810. doi:10.1001/jama.2016.0287
2. MedlinePlus. Procalcitonin Test. https://medlineplus.gov/lab-tests/procalcitonin-test/. Accessed March 19, 2025.
3. MedlinePlus. Lactate Test. https://medlineplus.gov/lab-tests/lactate-test/. Accessed March 19, 2025.
4. Mayo Medical Laboratories. Turnaround Times (TAT) in the Laboratory. http://a1.mayomedicallaboratories.com/webjc/attachments/67/da012dd-turnaround-times-tat-in-laboratory.pdf. Accessed March 19, 2025.
5. MedlinePlus. Blood Culture. https://medlineplus.gov/ency/article/003744.htm. Accessed March 19, 2025.
6. MyPathologyReport.ca. How to Read Your Blood Culture Report. https://www.mypathologyreport.ca/how-to-read-your-blood-culture-report/. Accessed March 19, 2025.
7. Cytovale. Our Science. https://cytovale.com/our-solution/our-science/. Accessed March 19, 2025.
8. Sepsis Alliance. What Is Sepsis? https://www.sepsis.org/sepsis-basics/what-is-sepsis/. Accessed March 19, 2025.
9. Afzal MS, Nandan Chennuri R, Naveed H, Raveena Bai B, Hanif R, Shahzad Z, Umer M, Saleem F. Comparison of Clinical Outcomes Between Culture-Positive and Culture-Negative Sepsis and Septic Shock Patients: A Meta-Analysis. Cureus. 2023 Feb 24;15(2):e35416. doi: 10.7759/cureus.35416. PMID: 36987463; PMCID: PMC10040220.)