Neutropenic Sepsis
A life-threatening oncological emergency in which chemotherapy-induced collapse of the neutrophil count removes the main defence against bacteria, so a fever after chemotherapy is treated as sepsis and given broad-spectrum antibiotics within one hour, before the neutrophil count is even known.
In a nutshell
Chemotherapy destroys neutrophils selectively because they divide fastest and live shortest, removing the cells that both fight bacteria and generate the visible signs of infection. Fever after chemotherapy is treated as sepsis and antibiotics are given within one hour, before the count or cultures are known.
Classic presentation
A patient who has had chemotherapy in the last 1–2 weeks develops a fever, feels generally unwell, and has few or no localising signs of infection on examination.
Key points
- Neutrophils have the shortest marrow lifespan, so they fall first and fastest after chemotherapy, with a nadir typically 7–14 days post-cycle.
- The signs of infection (pus, consolidation, a strong fever response) are themselves neutrophil-dependent, so a neutropenic patient can look deceptively well despite overwhelming infection.
- Antibiotics are given within one hour of suspicion, not after the FBC or cultures confirm neutropenia: delay costs survival.
- The source is often occult: gut mucosal translocation or a central line, which is why therapy is broad-spectrum rather than targeted at a found focus.
- This is a same-day emergency requiring immediate senior and haematology/oncology escalation, not routine assessment.
First-line investigation
None: investigations (FBC, cultures, lactate) are sent alongside, never before, the first dose of antibiotics.
First-line management
Empirical broad-spectrum intravenous antibiotics within one hour of presentation, per local neutropenic sepsis protocol, given before the neutrophil count or culture results are available.
Exam traps
- The most common exam trap: a stem describes a well-looking patient post-chemotherapy with a fever, and the correct answer is still immediate antibiotics, not 'await FBC'.
- Do not wait for blood cultures or the neutrophil count to come back before treating: clinical suspicion alone is the trigger.
- Absence of a clear focus of infection does not make the diagnosis less likely: it is expected, because neutrophils are what normally localise infection.
Educational content pending clinical review. Not medical advice.