Cellulitis Diagnosis

Cellulitis is an infection of the deeper layers of the skin that causes swelling and pain in affected areas. The leg is the site most commonly affected by cellulitis, although the condition can affect any part of the body.


Some examples of cellulitis symptoms include:

  • Redness, heat, pain and swelling in affected areas.
  • Breaks in the skin such as cuts, wounds, burns, eczema or bite marks indicate a point of entry for bacteria to access the dermis and subcutis underneath the skin.
  • High fever, chills, shivering and nausea due to infection.
  • Confusion, rapid heart rate and shallow breathing are all indicators that the infection may have entered the bloodstream and caused septicemia.


An outline of the steps taken in the diagnosis of cellulitis is given below:

  • A detailed clinical history is obtained as the doctor will need to know about conditions such as diabetes or weakened immunity. The doctor will also want to rule out other conditions that can cause similar symptoms to cellulitis such as varicose eczema which can cause itchy skin and ulcers.
  • A physical assessment is performed to check for signs such as wounds or skin breaks near the affected area.
  • If there is an open wound, the doctor takes a swab from the area and sends it for laboratory testing so that the type of bacteria causing the infection can be identified.
  • A suitable antibiotic for targeting the bacteria is then selected.
  • Additional tests may be carried out if symptoms seem severe and hospitalization is required in cases of gangrene or toxic shock syndrome, for example. Blood tests will show whether the infection-fighting white blood cells are raised or the platelet count is low.
  • If uncontrolled diabetes is a contributing factor, then blood sugar may be high.
  • Blood creatinine may be raised in cases of group A streptococcal infection, toxic shock syndrome or clostridium infection.
  • Low blood bicarbonate levels indicate metabolic acidosis and septic shock.
  • Low blood albumin may indicate diffuse capillary leak syndrome which can lead to swelling of soft tissue and pulmonary edema.
  • A decreased calcium level indicates staphylococcal or streptococcal toxic shock syndrome.
  • Imaging studies such as X-ray, CT scan or MRI scan may help determine the extent of the infection and aid diagnosis.


  • http://www.nhs.uk/Conditions/Cellulitis/Pages/Introduction.aspx
  • http://medchiefs.bsd.uchicago.edu/documents/cellulitis.pdf
  • http://www.dermnet.org.nz/bacterial/pdf/cellulitis-dermnetnz.pdf
  • http://www.lb7.uscourts.gov/documents/ILND/CellulitisInfection.pdf

Further Reading

  • All Cellulitis Content
  • Cellulitis – What Causes Cellulitis?
  • Cellulitis – Cellulitis Treatment
  • Cellulitis – What is Cellulitis?

Last Updated: Feb 26, 2019

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.

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