Necrotizing Fasciitis

Jennifer T. Trent, MD, Robert S. Kirsner, MD

Disclosures

Wounds. 2002;14(8) 

In This Article

Diagnosis

Because of the rapid progression inherent in NF, it is important to recognize and treat NF quickly to reduce mortality.[1] The clinician should have a high index of suspicion and begin therapy immediately based on the clinical findings, such as appearance of the skin and extreme pain out of proportion to the clinical exam. This coupled with fever and a patient's toxic appearance is highly suggestive of NF.

Laboratory, radiologic, and histopathologic testing should be ordered to confirm the diagnosis ( Table 4 ).[1,2,9,13,25,27,28,30,31] A positive gram stain and blood cultures can guide antibiotic therapy. If BHS is causal, a rapid strep screen is a fast, noninvasive, inexpensive test that can detect the presence of antigens to group A Streptococcus.

Radiologic testing may detect air within the tissue, highly suggestive of NF.[2,27,28,30,31] Plain x-rays and ultrasound can be used; however, MRI and CT scans produce better quality images. MRI is superior to CT since it is less invasive; however, the images are equal in resolution quality.

Fine needle aspiration, frozen section of tissue biopsy, fascial biopsy, and skin biopsy for histopathology are all useful in diagnosis of NF.[16,23] The advantage of frozen section is speed, as results can be obtained relatively quickly. Surgical exploration can be of both diagnostic and therapeutic value. Pathognomonic for NF is a positive "finger" test.[23] The finger test can be used to delineate the extent of infection into the adjacent normal appearing skin. It requires a 2cm vertical incision be made into the skin to the deep fascia. Lack of bleeding may be seen or a murky dishwater pus exudate may ooze from the incision site. An index finger, or hemostat, is gently pushed forward into the normal appearing tissue and the level of the junction of the subcutaneous tissue and the deep fascia. Normally, subcutaneous tissue adheres tightly to the deep fascia. If the subcutaneous tissue is easily dissected off the fascia, the finger test is positive. Liquefactive necrotic tissue or pus can also be found in between the fascial planes in NF.

processing....