Fever, infection and sepsis: the bedside signs !

Syndrome

Sepsis is an infection that harms the organs; warning signs are fast breathing, confusion and low blood pressure.

Updated 2026-11-01

See it in 3D: Kidneys · Skin · Peritoneum

What it is

Sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection. Not every febrile patient has sepsis, and not every septic patient has fever. Recognizing it early at the bedside, from vital signs and mental state, is what most changes its outcome.

Key findings

High or low temperature; rigors.
Tachycardia and tachypnea.
Altered mental state: confusion, drowsiness or agitation.
Hypotension, prolonged capillary refill, cold and mottled skin.
Falling urine output.
Source of infection: lung, urine, abdomen, skin and soft tissue, catheters, meninges.

Pathophysiology

Microbial products activate innate immunity and cytokines are released that cause fever, vasodilation and leaky capillaries.
Vasodilation and fluid leak into the tissues cause hypotension (distributive shock); the skin may be warm at first and later cold and mottled.
Activation of clotting in the microcirculation forms microthrombi and consumes platelets and factors.
Hypoperfusion and mitochondrial failure raise lactate and cause organ dysfunction: confusion, oliguria, hypoxemia, jaundice and thrombocytopenia.
Fever occurs because cytokines raise the hypothalamic set point.

Common causes

Lung: community- or hospital-acquired pneumonia.
Urinary tract: pyelonephritis and catheter-associated infection.
Abdomen: peritonitis, cholangitis, abscesses.
Skin and soft tissue, surgical wounds and venous catheters.
Nervous system: meningitis and meningococcemia.
In tropical areas, such as much of Colombia, the differential of fever includes malaria, dengue and leptospirosis.

Tests that confirm it

Lactate, blood count, renal and liver function, arterial blood gases and clotting tests.
Blood cultures and cultures from the source before antibiotics, without delaying them.
Imaging guided by the suspected source (chest X-ray, abdominal ultrasound).

Test yourself

Think of the answer, then tap the question to see it.

What are the three qSOFA criteria?

Respiratory rate of 22 or more per minute, altered mental state and systolic blood pressure of 100 mmHg or less.

Why does the absence of fever not rule out sepsis in an older adult?

The febrile response may be blunted; sepsis can show only as confusion, falls, tachypnea or hypothermia, which carries a worse prognosis.

What mechanism explains the hypotension of septic shock?

Cytokine-driven peripheral vasodilation and capillary leak (distributive shock), sometimes with myocardial dysfunction.

What does fever with a rapidly spreading petechial rash suggest?

Meningococcemia or another severe sepsis with disseminated intravascular coagulation: an emergency needing immediate assessment.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

← All of the clinical exam

Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: Sepsis: MedlinePlus (MedlinePlus, U.S. National Library of Medicine, 2026); About Sepsis | Sepsis | CDC (Centers for Disease Control and Prevention, 2026).

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Representative model, for educational purposes only.