Temperature spike on the ward
Is this sepsis? Screen, examine for the source, take cultures, and give antibiotics within an hour if septic.
"Bed 4 has a temperature of 38.6 °C. Can I give paracetamol?" He is 66, 5 days after a right hemicolectomy. Pulse 108, BP 112/70, RR 20, SpO₂ 95% on air. His abdomen is more tender than yesterday. His cannula in the left forearm is red and sore. He has a urinary catheter. He had loose stools twice today.
What are the likely sources, what do you send, and does he need antibiotics tonight?
- Sepsis screen firstBP, RR, mental state, lactate, urine output, NEWS2.
- Septic or neutropenicCultures and IV antibiotics within 1 hour, per policy.
- Think by day after surgeryDifferent causes at different times.
- Look at every possible sourceChest, wound, drains, abdomen, every cannula, catheter, calves, skin, stool, neck.
- Cultures before antibioticsTwo sets of blood cultures, urine, wound swab, stool if diarrhoea.
- Remove the causeInfected cannula, unneeded catheter.
- Not every fever needs antibioticsAtelectasis, drugs, transfusion, DVT, alcohol withdrawal.
- Sepsis with low BP or lactate above 2
- Neutropenic or on chemotherapy
- NEWS2 5 or more, or a single 3
- New confusion
- New abdominal pain after bowel surgery
- Rigors
| Fever | 38 °C or above |
| Hypothermia | Below 36 °C is also a sepsis warning |
| Lactate | Above 2 mmol/L (18 mg/dL) is worrying, above 4 (36 mg/dL) severe |
| Day 0–2 after surgery | Often inflammatory response or atelectasis |
| Day 3–5 | Pneumonia, urine, cannula |
| Day 5–10 | Wound infection, anastomotic leak, abscess, DVT or PE |
| Neutropenic | Antibiotics within 1 hour |
| Paracetamol | 1 g (max 4 g a day, 15 mg/kg if under 50 kg) |
Check every dose against a current drug reference and your hospital protocol.
On this page
On the phone
- Other observations and NEWS2? Any sepsis features (fast pulse, low BP, fast breathing, confusion, low urine)?
- Cannulas, central line, catheter, recent surgery or chemotherapy?
- Already on antibiotics? Allergies?
- Yes, the nurse can give paracetamol, but you are still coming to see the patient.
When you arrive
- Sepsis screenObservations, lactate, urine output, mental state.
- ChestRR, crackles, sputum, oxygen need.
- Abdomen and woundTenderness, distension, wound redness, drain fluid.
- Lines and catheterEvery cannula site, central line exit, catheter and urine.
- Legs and skinCalves, pressure areas, rash.
- Stool and neckDiarrhoea (C. difficile), neck stiffness.
By day after surgery
- Day 0–2Inflammatory response, atelectasis, transfusion, early aspiration
- Day 3–5Pneumonia, urinary infection, cannula phlebitis
- Day 5–10Wound infection, anastomotic leak, abscess, DVT or PE
- Any timeDrugs, alcohol withdrawal, C. difficile, line infection
Differential diagnosis
| Cause | Clues | Test |
|---|---|---|
| Pneumonia or aspiration | Cough, crackles, rising oxygen need | Chest X-ray, sputum |
| UTI | Catheter, burning, cloudy urine, loin pain | Urine culture (from catheter port) |
| Cannula or line infection | Red, painful cannula site, central line | Blood cultures from line and periphery, tip culture |
| Wound infection or collection | Red wound, swinging fever, pain | Swab, ultrasound or CT |
| Anastomotic leak | Day 3–8, tachycardia, new AF, pain, ileus, rising CRP | CT with contrast |
| C. difficile | Diarrhoea after antibiotics or PPIs | Stool toxin or PCR; isolate |
| DVT or PE | Leg swelling, low oxygen, fast pulse | Doppler, CTPA |
| Dengue, malaria, typhoid | Fever started before admission, season, low platelets | CBC, NS1, malaria test, blood culture |
| Drug fever | New drug, rash, eosinophilia | Clinical; stop the drug |
| Transfusion reaction | During or after blood | Stop transfusion; see transfusion guide |
| Alcohol withdrawal | Tremor, sweating, 1–3 days after admission | Clinical |
Who needs antibiotics tonight?
Cultures, antibiotics within 1 hour, fluids, senior
Cultures, then targeted antibiotics
Paracetamol, observe, repeat observations, review in the morning
Don't just treat the number. A temperature with a normal pulse in a well patient may need only paracetamol and a look. A temperature with a fast pulse and low BP needs antibiotics within the hour.
Investigations
| Test | Why |
|---|---|
| Blood cultures (2 sets, different sites) | Bacteraemia; before antibiotics |
| CBC, CRP | Infection, neutropenia |
| Urea, creatinine, electrolytes, LFTs | Organ function |
| Lactate | Severity |
| Urine culture | UTI |
| Chest X-ray | If chest signs or rising oxygen |
| Wound swab, cannula tip | Local infection |
| Stool for C. difficile | Diarrhoea |
| Ultrasound or CT | Collection, leak |
| Dengue NS1, malaria test | In season or fever before admission |
Treatment
- Infected cannula: remove it, send the tip if there's pus, treat cellulitis.
- C. difficile: stop unnecessary antibiotics and PPIs, isolate, oral vancomycin per policy.
- Catheter: remove if not needed; change before taking a urine sample.
- Sepsis: follow the sepsis pathway.
Common mistakes
- Prescribing paracetamol on the phone and not seeing the patient.
- Not looking at every cannula site.
- Starting antibiotics without cultures (or delaying antibiotics for cultures in sepsis).
- Calling fever on day 5 after bowel surgery "just the chest".
- Missing C. difficile because nobody asked about diarrhoea.
- Forgetting dengue and malaria in season.
Document
Temperature and observations, source found, cultures sent, antibiotics and time given, plan, and when to recall you.
Frequently asked questions
What causes fever on day 1 after surgery?
Usually the normal inflammatory response or atelectasis, though infection and transfusion reactions can also occur.
Should all fevers in hospital be treated with antibiotics?
No. Treat if there are signs of sepsis or a clear bacterial source. Otherwise investigate, observe and review.
What causes fever on day 5 after surgery?
Wound infection, anastomotic leak, collection, pneumonia, UTI, line infection and DVT or PE.
What should be done with an infected cannula?
Remove it, send the tip for culture if there's pus, take blood cultures if the patient is febrile, and treat any surrounding cellulitis.
Test yourself
Exam-style questions on this guide, from our two question banks. Choose an answer to see why each option is right or wrong.
1. A patient has a fever on day 6 after bowel resection with new abdominal tenderness. What must be excluded?
Answer: Anastomotic leak. Days 5–10 after bowel surgery, fever with abdominal signs suggests leak or abscess: CT and surgical review.
- Transfusion reaction: Not this timing.
- Normal recovery: No.
- Atelectasis: More typical days 0–2.
- Drug fever: Less likely with tenderness.
2. A patient develops diarrhoea and fever after a week of IV co-amoxiclav. What should be tested?
Answer: Stool for C. difficile. C. difficile follows antibiotic use; isolate and test stool.
- Widal: Not useful.
- Urine culture: Not first.
- Blood film for malaria only: Not first.
- Sputum: No.
3. A febrile patient has a red, tender cannula site. What is the first step?
Answer: Remove the cannula. Remove infected lines and send cultures; consider antibiotics if cellulitis or bacteraemia.
- Apply ice: Not enough.
- Change dressing only: No.
- Flush it: Spreads infection.
- Leave it and add antibiotics: Source must be removed.
4. An elderly inpatient on co-amoxiclav for pneumonia develops 6 watery stools a day, fever and WBC 18 × 10⁹/L. C. difficile toxin is positive. What is first-line therapy?
Answer: Oral vancomycin. C. difficile infection follows broad-spectrum antibiotics (cephalosporins, clindamycin, co-amoxiclav, quinolones) and PPIs. Stop the precipitating antibiotic if possible, isolate with contact precautions (alcohol gel doesn’t kill spores — wash with soap and water). First-line: oral vancomycin or fidaxomicin (fewer recurrences); metronidazole only if these unavailable for mild disease. Fulminant disease: oral/NG vancomycin plus IV metronidazole, surgical review. Recurrence: fidaxomicin, bezlotoxumab or faecal microbiota transplant.
- IV vancomycin infusion: IV vancomycin does not reach the colon.
- Continue co-amoxiclav: The causative antibiotic should be stopped if possible.
- Loperamide and fluids: Loperamide risks toxic megacolon.
5. On day 5 after a right hemicolectomy, a patient has fever 38.8 °C, tachycardia, abdominal pain and rising CRP. What is the most likely cause?
Answer: Anastomotic leak. Postoperative fever timing: day 0–2 — physiological inflammatory response, atelectasis, transfusion reaction; day 3–5 — pneumonia, UTI, line infection; day 5–7 — anastomotic leak, intra-abdominal abscess, wound infection; after day 7 — DVT/PE, abscess, drug fever. Anastomotic leak presents with fever, tachycardia, ileus, abdominal pain, rising CRP; CT with contrast confirms. Treat with resuscitation, antibiotics, drainage or relaparotomy.
- Atelectasis: Atelectasis occurs on days 1–2.
- Transfusion reaction: Transfusion reactions occur during transfusion.
- Drug fever: Drug fever is a diagnosis of exclusion.
6. Which part of the brain directly controls autonomic reflexes and body temperature?
Answer: Hypothalamus. The hypothalamus integrates autonomic control: temperature, hunger, thirst, water balance (ADH), circadian rhythms and pituitary function. It acts through brainstem autonomic centres and the pituitary.
- Thalamus: A sensory relay station.
- Cerebral cortex: Higher functions; it can influence but does not directly control autonomic reflexes.
- Cerebellum: Coordinates movement.
- Basal ganglia: Control movement initiation.
7. What is the most common organism causing surgical site infection after clean surgery?
Answer: Staphylococcus aureus. In clean surgery (no entry into gut, airway or urinary tract), skin flora such as Staphylococcus aureus (including MRSA) and coagulase-negative staphylococci cause most infections. After bowel surgery, gut organisms (E. coli, anaerobes) are more common. Prevention: skin preparation, prophylactic antibiotics at induction, normothermia and good technique.
- Escherichia coli: Common after bowel surgery.
- Pseudomonas aeruginosa: Burns and hospital-acquired infections.
- Clostridium perfringens: Gas gangrene; rare.
- Streptococcus pneumoniae: Pneumonia.
References and dose sources
- Paracetamol dosing: Drugs.com: Acetaminophen (paracetamol) dosage (see also our paracetamol dose page)
- Piperacillin-tazobactam dosing: Drugs.com: Piperacillin/tazobactam dosage (see also our piperacillin-tazobactam dose page)
- Flucloxacillin dosing: Drugs.com: Flucloxacillin (international) (see also our flucloxacillin dose page)
- Vancomycin dosing: Drugs.com: Vancomycin dosage (see also our vancomycin dose page)
International guidance is linked where it reflects good practice. Where your hospital’s protocol differs, follow your hospital.