Postoperative Day 4 Fever After Sigmoid Resection
Examine the surgical wound first (Option C), as fever on postoperative day 4 after sigmoid resection is equally likely to represent a surgical site infection as other causes, and wound inspection is the most critical initial step. 1, 2
Why Wound Examination Takes Priority
By postoperative day 4, the benign inflammatory response from surgery has resolved, and fever now shifts significantly toward infectious causes rather than normal postoperative inflammation. 1, 2 The Infectious Diseases Society of America specifically states that surgical site infections rarely occur during the first 48 hours after surgery, but after 96 hours (day 4), fever is equally likely to be caused by a surgical site infection or another infection. 3, 1
For sigmoid resection specifically, this is particularly critical because operations involving nonsterile tissue such as colonic mucosa can rapidly progress to involve deeper structures including fascia, fat, or muscle, and may be caused by combinations of aerobic and anaerobic bacteria. 3
What to Look for During Wound Examination
The Infectious Diseases Society of America recommends inspecting the surgical incision thoroughly for: 1, 2
- Purulent drainage (obtain Gram stain and culture immediately if present)
- Spreading erythema (measure extent from incision)
- Induration, warmth, tenderness, or swelling
- Any necrosis (requires immediate intervention)
If erythema extends >5 cm from the incision with induration, or if any necrosis is present, immediate intervention is required with opening of the suture line, empiric antibiotics, and dressing changes. 1, 2
Temperature-Guided Management Algorithm
For patients with temperature ≥38.5°C or heart rate ≥110 beats/min, the wound generally requires opening of the suture line plus antibiotics. 3
For patients with temperature <38.5°C without tachycardia, observation and dressing changes may suffice if the wound appears benign. 3
Antibiotic Selection for Sigmoid Resection Infections
Because sigmoid resection involves nonsterile colonic tissue, empiric coverage must include both aerobic and anaerobic bacteria. 3 The Infectious Diseases Society of America recommends: 1
- Cephalosporin + metronidazole, OR
- Levofloxacin + metronidazole, OR
- Carbapenem
(This differs from clean wounds of trunk/extremities where cefazolin alone would suffice.) 1
When to Add Blood Cultures and Chest X-Ray
Blood cultures should be obtained when temperature ≥38°C is accompanied by systemic signs of infection beyond isolated fever (such as hemodynamic instability, altered mental status, or signs of bacteremia/sepsis). 1, 2 Blood cultures before wound examination waste time when the wound is the most likely source.
Chest X-ray is not mandatory on day 4 if fever is the only indication, as respiratory causes are less likely than wound infection at this timepoint after abdominal surgery. 1 However, chest X-ray becomes indicated if respiratory symptoms develop. 1
Common Pitfalls to Avoid
- Assuming atelectasis without investigation - atelectasis should be a diagnosis of exclusion, not a default explanation for day 4 fever. 2
- Starting empiric antibiotics before obtaining wound cultures - this compromises diagnostic accuracy. 2
- Delaying wound inspection - even if other findings seem unremarkable, isolated fever on day 4 mandates wound evaluation. 2
- Missing rare early severe infections - while uncommon, group A streptococcal or clostridial infections can present with severe systemic toxicity and require immediate recognition. 3, 1
Red Flags Requiring Immediate Escalation
Immediately escalate care if any of the following develop: 2