In a 45-year-old woman on postoperative day 5 after hysterectomy who has an isolated fever with a clean surgical wound, what is the most appropriate next investigation?

Postoperative Day 5 Fever Management

In a 45-year-old woman on postoperative day 5 after hysterectomy with isolated fever and a clean wound, the most appropriate next step is urinalysis and culture (Answer B), as fever at this timepoint shifts probability significantly toward infectious causes, with urinary tract infection being the most common source, particularly if an indwelling catheter was present for ≥72 hours. 1

Rationale for Urinalysis and Culture

• Fever on postoperative day 5 represents a critical timepoint where the benign systemic inflammatory response from surgery (which typically resolves within 48-72 hours) has passed, making infection the primary concern rather than normal postoperative inflammation. 1, 2

• Urinary tract infections are the leading infectious cause of postoperative fever, especially in gynecologic surgery patients who routinely have indwelling bladder catheters perioperatively. 1

• Duration of catheterization is the single most important risk factor for UTI development, and the American College of Critical Care Medicine specifically recommends urinalysis and culture for febrile patients who have had indwelling bladder catheters for ≥72 hours, even without urinary symptoms. 3, 1

• Hysterectomy patients are at particularly high risk because the procedure involves manipulation of the urinary tract and typically requires catheterization during and after surgery. 1

Why Other Options Are Less Appropriate

CBC and Blood Cultures (Option A)

• Blood cultures should be reserved for patients with temperature ≥38°C accompanied by systemic signs of infection such as hemodynamic instability, altered mental status, or signs of bacteremia/sepsis beyond isolated fever. 1, 2

• The yield of blood cultures is low in patients with isolated fever without systemic signs, making this a less targeted initial approach. 1

Chest X-ray (Option C)

• A chest radiograph is not mandatory during the initial 72 hours postoperatively if fever is the only indication, and should only be obtained if respiratory signs or symptoms develop. 3, 1

• Atelectasis should be a diagnosis of exclusion, and assuming it as the cause without investigation is a common pitfall. 1, 2

Medication Review (Option D)

• Drug-induced fever typically develops with a mean lag time of 21 days (median 8 days) after drug initiation, making it less likely on postoperative day 5. 4

• Medication review becomes increasingly important when standard infectious workup (including urinalysis, wound inspection, and imaging) is negative or when fever persists despite appropriate antibiotics, but it should not be the initial step. 4

Complete Evaluation Algorithm for Day 5 Fever

Immediate Actions

1. Perform urinalysis and urine culture as the first diagnostic test, particularly given the gynecologic surgery context. 3, 1

2. Inspect the surgical wound thoroughly for purulent drainage, spreading erythema (>5 cm from incision with induration), warmth, tenderness, swelling, or necrosis, though the question states the wound is clean. 3, 1

3. Do not culture the wound if there are no symptoms or signs suggesting infection, as swabbing clean wounds is rarely helpful. 3, 1

Subsequent Steps if Urinalysis is Negative

• Obtain blood cultures if fever persists or systemic signs develop. 1

• Consider imaging studies (CT of pelvis/abdomen) in collaboration with the surgical service if the etiology remains unclear, as surgical site infections account for approximately 25% of costs associated with surgical procedures and most frequently manifest between postoperative days 4-6. 1, 2

• Maintain high suspicion for deep venous thrombosis or pulmonary embolism, especially in patients who are sedentary, have lower limb immobility, have a malignant neoplasm, or are taking oral contraceptives. 3

Critical Pitfalls to Avoid

• Starting empiric antibiotics before obtaining appropriate cultures compromises diagnostic accuracy and should be avoided unless the patient shows signs of severe sepsis or hemodynamic instability. 1, 4

• Delaying investigation because other findings are unremarkable is inappropriate, as isolated fever on day 5 warrants targeted evaluation. 1

• Assuming atelectasis without investigation is a common error; atelectasis should be a diagnosis of exclusion. 1, 2