A 35-year-old male with a history of diabetes and pericarditis, status post pericardiectomy 3 years ago, presented with a painful lesion on his anterior chest wall. One month prior, the patient reported a bump at his sternotomy scar base which extruded a piece of suture when squeezed and subsequently healed. Two days ago, the patient developed diffuse right-sided chest pain. During the past 24 hours, an enlarging, erythematous, painful, non-draining lesion developed at the base of his scar. He reports subjective fever. He denies shortness of breath, exertional chest pain, nausea, and vomiting.
Vitals: Within normal limits for age, afebrile
Constitutional: Non-toxic appearing male of stated age in no apparent distress
Cardiovascular: Regular rate and rythum
Pulmonary: Lungs clear to auscultation bilaterally
Skin:
- A tender, erythematous, fluctuant, 1 x 1 centimeter area at the base of a well-healed sternotomy scar, without drainage
- There is no significant surrounding erythema, induration, or fluctuance
The remainder of the exam is unremarkable.
WBC: 20.22 109/L
Erythrocyte sedimentation rate (ESR): 65 mm/hr
C-reactive protein (CRP): 319.23 mg/L
Glucose: 312 mg/dL
A superficial abcess
On exam, the abscess appears superficial, requiring simple incision and drainage (I&D).
An important next step in this patient’s assessment was a bedside ultrasound, which revealed a communicating fluid collection extending to six centimeters, concerning for deeper infection.
Subsequent computed tomography revealed a large right anterior mediastinal collection contiguous with the pericardium. This prompted the administration of intravenous antibiotics and immediate admission to the coronary care unit for surgical drainage.
This case illustrates the fact that the nature and extent of skin and soft tissue infections are notoriously difficult to determine by physical exam alone. Several studies have demonstrated that POCUS has a higher sensitivity and specificity than physical exam for diagnosing the presence of an abscess [1]. Furthermore, physical exam has been shown to be an unreliable predictor of abscess penetration [2]. In this case, the use of POCUS altered this patient’s clinical course by revealing the extent of the collection, allowing him to receive the appropriate surgical intervention and IV antibiotics.
Take-Home Points
- A bedside ultrasonogram has higher sensitivity and specificity than a physical exam for abscess diagnosis in several studies.
- A physical exam is an unreliable predictor of abscess penetration and should be supplemented with a bedside ultrasound.
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- Subramaniam, Sathyaseelan, et al. “Point‐of‐care ultrasound for diagnosis of abscess in skin and soft tissue infections.” Academic Emergency Medicine 23.11 (2016): 1298-1306. PMID: 27770490
- Gaspari, Romolo J., Alexandra Sanseverino, and Timothy Gleeson. “Abscess incision and drainage with or without ultrasonography: a randomized controlled trial.” Annals of emergency medicine 73.1 (2019): 1-7. PMID: 30126754
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