Postoperative Tachycardia After Low Anterior Resection
A 58-year-old man is on postoperative day 6 after a laparoscopic low anterior resection with primary anastomosis for rectal cancer. He has fever 38.7 C, heart rate 118/min, blood pressure 102/64 mmHg, respiratory rate 22/min, and urine output 20 mL/h over the last 4 hours. He reports increasing abdominal pain and distension. Examination shows generalized tenderness without rigidity, and the stoma is functioning. WBC is 14,200/microL, lactate 2.8 mmol/L, and creatinine has risen from 0.9 to 1.4 mg/dL. Contrast-enhanced CT shows a small pelvic fluid collection adjacent to the anastomosis with fat stranding but no free intraperitoneal air. The surgical resident suggests antibiotics and observation because there is no free air. The patient is otherwise alert and has no comorbidities.
1. How do you interpret the CT finding, and what is your next step? Explain why the absence of free air is not reassuring.
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The CT is concerning for an anastomotic leak or pelvic abscess even without free air. A low rectal anastomosis can leak in a contained fashion, producing a small collection and fat stranding rather than massive pneumoperitoneum. The physiology is more important than the single CT sign: fever, tachycardia, hypotension, oliguria, rising creatinine, and lactate 2.8 indicate early sepsis and hypoperfusion.
Next step is urgent surgical evaluation, not observation. Obtain blood and urine cultures, start broad-spectrum antibiotics after cultures, and resuscitate with balanced crystalloids. If he has peritonitis, worsening hypotension, or fails to improve quickly, return to the operating room for source control. If he remains stable and the collection is accessible, percutaneous drainage plus antibiotics may be a bridge, but a low rectal anastomosis with systemic toxicity often needs operative washout and possibly diversion. Do not let the absence of free air delay escalation.
2. What would you tell the resident who wants to continue antibiotics and observation? Include the specific triggers for immediate reoperation.
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Tell the resident that a normal-appearing CT in one finding does not exclude a leak and that the patient has sepsis with end-organ dysfunction. The plan should be reassessed now, not after another day of fever. Escalate to the attending surgeon and reassess at the bedside.
Immediate reoperation is triggered by diffuse peritonitis, hemodynamic instability despite fluids, worsening lactate or oliguria, a rapidly enlarging collection, or clinical deterioration. A stable patient with a small contained collection may be considered for drainage, but this is a narrow window and requires close monitoring. Document the reasoning and the contingency plan. The key judgement is that source control is time-sensitive and antibiotics alone do not drain a collection.