Post-operative pyrexia is a fever after surgery, and the five Ws are the checklist for its source: wind (the chest), water (the urine), wound, walking (the veins) and wonder drugs. The CST clinical station is not marking whether you know the mnemonic. It is marking whether you assess the patient by ABCDE, score the NEWS2, treat sepsis on the NICE NG253 clock if the score demands it, and then hunt the source in a structured way.

Key takeaways

  • The five Ws are a teaching heuristic for the source of post-operative pyrexia, not a guideline; the day-ranges often attached to them are tradition rather than evidence
  • NEWS2 scores temperature at 38.1 to 39.0 as 1 point and 39.1 or more as 2 points; a temperature of 35.0 or below scores 3
  • NICE NG253 defines high risk of severe illness or death from sepsis as suspected infection with a NEWS2 of 7 or more: antibiotics within 1 hour, a fluid bolus within 1 hour, and a senior clinical decision maker
  • A NEWS2 of 5 or 6 is moderate risk and needs review of the patient and the venous lactate within 1 hour
  • Cultures before antibiotics, and the operation note before the differential
  • An anastomotic leak, a collection and a line infection are the surgical sources the mnemonic under-serves

How does post-operative pyrexia present, and what are the five Ws?

Post-operative pyrexia presents as a temperature above the patient's normal on the observation chart, usually flagged by nursing staff, and the five Ws organise the search for its cause. Wind is atelectasis or pneumonia; water is a urinary tract infection, often catheter-related; wound is surgical site infection or a deeper collection; walking is deep vein thrombosis or pulmonary embolism; and wonder drugs are drug fever, transfusion reactions and, in practice, the antibiotic that has bred a Clostridioides difficile infection.

In practice, add three more sources that the mnemonic misses. A leak from any anastomosis, an intra-abdominal collection, and any indwelling line, particularly a central venous catheter. On a surgical ward these are the fevers that kill.

What is the immediate management of post-operative pyrexia, A to E?

Immediate management of post-operative pyrexia is a full ABCDE assessment with the NEWS2 calculated at the bedside, because the score decides whether this is a fever to investigate or a sepsis to treat now.

Airway and breathing

Respiratory rate, saturations and a chest examination. A respiratory rate of 21 to 24 scores 2 on NEWS2 and 25 or more scores 3, and it is the parameter that most often reveals a chest source or early sepsis before the blood pressure moves.

Circulation

Pulse, blood pressure, capillary refill and urine output, then intravenous access and bloods including blood cultures and a venous gas for lactate. If the NEWS2 is 7 or more, NICE NG253 recommends a 250 ml crystalloid bolus over 10 to 15 minutes, repeated as needed to 1,000 ml with reassessment after each.

Disability and exposure

Consciousness level, since new confusion scores 3 on NEWS2, and capillary glucose. Then expose: the wound under the dressing, every drain, every cannula and line site, the catheter, the calves, and the abdomen for peritonism. The examination is where the five Ws are actually applied.

What investigations does post-operative pyrexia need?

Post-operative pyrexia needs the investigations that find a source, and they are chosen by the examination rather than sent as a panel. The fixed core is a full blood count, urea and electrolytes, CRP, blood cultures taken before antibiotics, and a lactate on the gas if the NEWS2 is raised.

  • Chest: a chest radiograph, and a sputum culture if there is one
  • Urine: dipstick and culture, and remove or replace a catheter that is no longer needed
  • Wound: a swab of any discharge, and an ultrasound or contrast CT for a suspected collection or anastomotic leak
  • Walking: a Wells score and a proximal leg vein ultrasound within 4 hours if DVT is likely under NICE NG158, or CTPA if PE is likely
  • Wonder drugs: review the drug chart, the transfusion record and the antibiotic course, and send stool for C. difficile if there is diarrhoea
  • Lines: inspect every site, culture from the line and peripherally, and take out any line without a current indication

What is the definitive management of post-operative pyrexia?

Definitive management of post-operative pyrexia is treatment of the source you have found, and for a patient at high or moderate risk under NICE NG253 it starts before the source is known. That means broad-spectrum intravenous antibiotics within 1 hour of a NEWS2 of 7 or more, chosen with the local antimicrobial guideline and adjusted when cultures return.

That said, not every post-operative fever is sepsis. A patient with a NEWS2 of 1 to 4 and a clear chest source can be treated with physiotherapy, oxygen and, if pneumonia is likely, antibiotics for pneumonia. A collection needs drainage. A leak needs the ACPGBI pathway and the operating consultant. A line infection needs the line out.

NG253 also directs you to find and control the source: it lists source control as part of the initial management, not a later step. A fever without a source in a patient who is well is observed with repeat observations and a review time written down.

When do I escalate post-operative pyrexia, and to whom?

Escalate post-operative pyrexia on the NEWS2 triggers and on clinical concern, whichever comes first. The Royal College of Physicians chart sets an aggregate of 5 or 6 as the key threshold for an urgent response by a clinician competent in acute illness, and 7 or more as the emergency threshold with a team that includes critical care skills and consideration of level 2 or 3 care.

NICE NG253 adds that a single parameter scoring 3 with a NEWS2 below 7 becomes high risk once a medical review confirms it. For a surgical patient, call the registrar at the same time as you treat, and the operating consultant if the source is the operation. Involve critical care when the patient needs vasopressors, has a rising lactate after 1,000 ml, or has organ dysfunction.

What is the interviewer listening for in a post-operative pyrexia scenario?

  • The NEWS2 calculated and stated as a number, then matched to the NG253 risk band
  • Cultures before antibiotics, and antibiotics within the hour if the band demands it
  • The five Ws used as an examination checklist, with leak, collection and line added out loud
  • The operation note read: what was joined, what was left in, and which day this is
  • A plan with a review time, the outstanding results named, and a named person told

What are the common mistakes with post-operative pyrexia?

The commonest mistake with post-operative pyrexia is giving paracetamol and a broad antibiotic without cultures, a NEWS2 or an examination, so the fever settles and the collection grows. The second is reciting the five Ws by day number and stopping there.

  • Treating the temperature as the problem rather than the score and the source
  • Missing a leak because the fever came on day 5 and the mnemonic said wound
  • Leaving a catheter or cannula in because nobody owned the decision to remove it
  • Not asking about diarrhoea and the antibiotic history
  • Escalating by adjective rather than by NEWS2 band and lactate

How this comes up at the CST interview

The CST management and clinical station sets post-operative pyrexia as a nurse's call about a temperature of 38.5 on a post-operative patient, and then asks what you do first, what you send and who you call. Score the NEWS2 aloud, apply NICE NG253, use the five Ws as your examination, and name the surgical sources the mnemonic misses. coresurgeryinterview holds 299 questions with AI-marked spoken practice, including this scenario, at /Question-Bank/Sample-Questions.