From the Guidelines
To diagnose sepsis, blood cultures should be obtained immediately before starting antibiotics, along with a complete blood count, comprehensive metabolic panel, lactate level, and procalcitonin test, as recommended by the most recent guidelines 1. When suspecting sepsis, it is crucial to perform a series of tests to identify the causative organism and guide targeted therapy.
- Blood cultures are essential to identify the causative organism and guide targeted therapy, and should be taken as soon as possible following onset of fever, ideally before starting antibiotics 2.
- A complete blood count (CBC) may show elevated white blood cell count or leukopenia, while the comprehensive metabolic panel can reveal organ dysfunction.
- Serum lactate levels above 2 mmol/L suggest tissue hypoperfusion and correlate with sepsis severity.
- Procalcitonin is often elevated in bacterial infections and can help distinguish sepsis from other inflammatory conditions. Additional tests should include:
- Urinalysis
- Chest X-ray
- Cultures from suspected infection sites (urine, sputum, wound, etc.)
- Point-of-care ultrasound may help identify infection sources
- CT Chest With IV Contrast, which has a high positive predictive value (PPV) for identifying septic foci, particularly in the chest (pneumonia) 1. These tests should be performed promptly as sepsis is a medical emergency requiring immediate intervention. The diagnostic approach follows the Sepsis-3 criteria, which define sepsis as life-threatening organ dysfunction caused by a dysregulated host response to infection, typically identified by a SOFA score increase of 2 or more points 1. Early recognition and testing are crucial for timely antibiotic administration and improved patient outcomes.
From the Research
Diagnostic Tests for Sepsis
To diagnose sepsis, the following tests can be performed:
- Blood cultures to identify the causative organism 3, 4
- Blood tests, including lactate levels, to assess the severity of sepsis 3, 4, 5
- Urine measurement to assess kidney function 4
- NEWS 2 or qSOFA score to assess the risk of sepsis 4
- Imaging studies, such as X-rays or CT scans, to identify the source of infection 3
Laboratory Tests
Laboratory tests, such as:
- Complete blood count (CBC) to assess for signs of infection or inflammation
- Blood chemistry tests to assess organ function
- Coagulation studies to assess for signs of disseminated intravascular coagulation (DIC)
- Arterial blood gas (ABG) to assess for signs of respiratory failure
Timing of Diagnostic Tests
Diagnostic tests should be performed promptly, ideally within 1 hour of suspected sepsis diagnosis 3, 6, 7, 5 The results of these tests can help guide treatment and management of sepsis.
Management of Sepsis
The management of sepsis involves:
- Early goal-directed resuscitation of the septic patient during the first 6 hours after recognition 3
- Administration of broad-spectrum antibiotics within the first hour of diagnosis 3, 6, 5
- Fluid resuscitation with lactated ringers or other crystalloids 5
- Vasopressor support with norepinephrine or dopamine 3
- Stress-dose steroid therapy for septic shock 3
- Recombinant activated protein C in patients with severe sepsis and high risk for death 3