Subinternship Medicine · Year 4 · from Subinternship Medicine
Case 1: Anchoring Bias and Premature Closure
Clinical Image
Source: Wikimedia Commons - Chest X-ray - CC BY-SA 4.0
Case Presentation
A 58-year-old woman with history of recurrent urinary tract infections presents to the emergency department with fever, dysuria, and suprapubic discomfort. Urinalysis shows pyuria with positive leukocyte esterase and nitrites. She is diagnosed with UTI and started on ciprofloxacin. She is admitted for IV antibiotics given mild acute kidney injury (creatinine 1.6 mg/dL from baseline 1.0 mg/dL). Despite 48 hours of appropriate antibiotics, her fever persists at 38.9 degrees Celsius, and she develops new confusion. The admitting team continues the UTI treatment plan. The covering sub-intern, reviewing the case during sign-out, asks "what else could this be?" and notes that the patient's confusion seems disproportionate to her degree of illness. Physical examination reveals subtle nuchal rigidity that was not previously documented. The sub-intern raises this concern with the senior resident, who agrees to perform a lumbar puncture. CSF analysis reveals 1,200 WBCs with 90% neutrophils, protein 180 mg/dL, and glucose 25 mg/dL (serum glucose 120 mg/dL). The patient has bacterial meningitis, likely from hematogenous spread. Broad-spectrum meningitis coverage is initiated, and she ultimately recovers with IV ceftriaxone and vancomycin for 14 days.
Key Learning Points
- Anchoring bias occurs when clinicians fixate on the initial diagnosis (UTI) and fail to adequately adjust when new information emerges (persistent fever, confusion)
- Premature closure means stopping the diagnostic search after finding one diagnosis without asking "what else could this be?"
- The "worst case scenario" or "can't miss" diagnoses should be considered for every presentation; meningitis should be on the differential for fever with altered mental status
- Speaking up about diagnostic concerns, regardless of hierarchy, can prevent missed diagnoses and improve patient outcomes