QI Series: Cellulitis vs Necrotizing Fasciitis

Case

A 50-year-old male was referred to the ED for evaluation of cellulitis. The patient had developed pain and swelling in his right groin region 5 days earlier. He had seen his physician 3 days before the ED visit and was started on Doxycycline. On the day of evaluation, he had returned to the office with increasing redness so was referred to the ED.

Additional History

He also noted the onset of shaking chills, fevers, and sweats. His past medical history was notable for diabetes, hypertension, and hyperlipidemia. He denied alcohol or recreational drug use.

Physical Exam

Temp 36.7C
Pulse 94 bpm
BP 119/67

He was an obese male, who was alert and cooperative. His right groin was notable for a 12 x 15 cm region of redness and swelling, extending from the groin distally. No fluctuance was noted and the genitalia were spared. The rest of the physical exam was normal.

ED Course

A CBC, electrolyte panel and blood cultures were ordered. IV Vancomycin was administered, and the patient was admitted to the on-call Hospitalist service with a diagnosis of cellulitis. At this point shift change occurred in the ED and care was handed off to the new ED team while awaiting transfer to the inpatient unit.

Hospital Course

Several hours later, the Hospitalist examined the patient and noted subcutaneous crepitus in the right thigh. Laboratory and R leg xray findings (right) included:

• WBC of 14.3
• Na of 134 mmol/L
• BUN of 55 mg/dL
• Creatinine of 3.5 mg/dL
• Glucose of 255 mg/dL

Hospital Course

A surgery consult was obtained and the patient was taken to the operating room later that night. Intraoperative findings included necrotic subcutaneous tissue from the inguinal ligament to just above the knee medially confirming a diagnosis of necrotizing fasciitis. Post-operatively, he became hypotensive and required vasopressor support in the ICU for 2 days. He underwent several additional debridement procedures in the operating room and was left with a 40 x 30 cm wound defect. He was ultimately discharged on hospital day number 9 with a wound VAC.

Commentary

Missed diagnoses in the ED result from both cognitive and systems failures.

Necrotizing fasciitis is typically a polymicrobial soft tissue infection that involves the skin, subcutaneous tissue, fascia, and muscle. Patient risk factors include injection drug use, diabetes, immunosuppression, and obesity. ^1,2  Given the predilection for deeper tissues, the cutaneous appearance of necrotizing fasciitis can be deceptively similar to simple cellulitis. Unlike cellulitis, these should be red-flag clues for necrotizing fasciitis:

• The skin overlying a necrotizing infection is often edematous beyond the borders of the erythema and may demonstrate blistering or bullae formation.
• The patient may complain of pain out of proportion to the degree of redness
• Direct palpation may demonstrate extreme tenderness and crepitus (the latter secondary to subcutaneous soft tissue gas).

Key ED Findings

Laboratory indicators of inflammation and end organ dysfunction have been found to be associated with necrotizing soft tissue infections ³ :

• CRP ≥150 mg/L
• WBC >15 /mm3
• HgB <13.5 g/L
• Sodium <135 mmol/L
• Cr >1.59 mg/dL
• Glucose >180 mg/dL

X-rays will occasionally demonstrate subcutaneous gas.

Shift Change

A shift change occurred and the patient remained in the ED for several hours prior to transfer to the inpatient unit. However, the patient was not re-evaluated nor were laboratory results reviewed. Shift change has long been known to be a vulnerable time in Emergency Departments and strategies have been proposed to interrupt errors that might otherwise be propagated. These strategies include checklists, rounding with off-going physicians, and the use of mnemonics. ⁴

Diagnosis Momentum

Finally, the patient presented to the ED pre-diagnosed by the outpatient physician as cellulitis. Thus, there may have been an element of “diagnosis momentum” at play here. The emergency physicians may have simply accepted this diagnosis and propagated this error downstream. This cognitive bias or disposition to respond is one of many that may influence decision making in the ED. ⁵

Summary

In this case, a confluence of factors conspired to result in failure to promptly diagnose the necrotizing soft tissue infection. The emergency physicians missed an opportunity to make a critical diagnosis and put the patient at risk for a worsened outcome.

Teaching Points

1. Consider necrotizing fasciitis in patients with concerning findings for serious soft tissue infections and risk factors. Purposefully attempt to rule out the condition by a careful examination and scrutiny of laboratory indicators.
2. Shift change is a vulnerable time in the ED. Use the opportunity to meet and examine all patients that you become responsible for.
3. When a patient is referred to the ED with a pre-diagnosed condition, do an independent assessment to confirm or refute the diagnosis.

Disclaimer: The cases in this series are very loosely based on an aggregate pool of known patient cases from around the country over the past decade, although the lessons are timeless.

Author information

Steven Polevoi, MD

ALiEM Guest Contributor
Medical Director and QI Director
Clinical Professor of Emergency Medicine
University of California, San Francisco

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