Pressure Injuries (Pressure Ulcers) and Wound Care Workup

Updated: Apr 29, 2022
  • Author: Christian N Kirman, MD; Chief Editor: John Geibel, MD, MSc, DSc, AGAF  more...
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Laboratory Studies

A complete blood count (CBC) with differential may show an elevated white blood cell (WBC) count indicative of inflammation or invasive infection. The erythrocyte sedimentation rate (ESR) should be determined. An ESR higher than 120 mm/hr and a WBC count greater than 15,000/µL suggest osteomyelitis.

Nutritional parameters should be evaluated to assess adequate nutritional stores needed for adequate wound healing. Useful tests include the following:

  • Albumin level - This should be optimized to at least 3.5 g/mL before flap reconstruction
  • Prealbumin level
  • Transferrin level
  • Serum protein level

When indicated by the specific clinical situation, the following laboratory studies should be obtained:

  • Urinalysis and culture in the presence of urinary incontinence
  • Stool examination for fecal WBCs and Clostridium difficile toxin when pseudomembranous colitis may be the cause of fecal incontinence
  • Blood cultures if bacteremia or sepsis is suggested

These patients often have anemia of chronic disease, suggested by a low mean corpuscular volume, and can be considered for a transfusion in order to achieve a preoperative hemoglobin level higher than 12 g/dL.


Imaging Studies

A diagnosis of underlying osteomyelitis can be evaluated first with plain films. Osteomyelitis may also be suggested by positive bone scan findings. A negative bone scan finding generally excludes osteomyelitis; however, patients with an open wound, such as a pressure injury, can often have a falsely positive bone scan. A positive bone scan finding can be evaluated further by means of magnetic resonance imaging (MRI) or bone biopsy (see below).



A tissue biopsy should be performed for wounds that do not demonstrate clinical improvement despite adequate care and for wounds in which tissue invasion by bacteria is suggested. This allows quantification and identification of bacterial species and their antibiotic susceptibilities. Biopsy also enables the clinician to distinguish between simple contamination and tissue invasion, an important distinction that is not revealed by the common practice of swabbing the wound surface for culture.

Tissue biopsy of chronic wounds is indicated to rule out the presence of an underlying malignancy (ie, Marjolin ulceration). Whenever a chronic pressure injury has been stable for months or years but has recently deteriorated, a biopsy should be performed. Scar carcinoma is uncommon and typically occurs in wounds that have been open for many years.

Bone biopsy is the criterion standard for the diagnosis of osteomyelitis within a pressure injury. [66] It should be considered in patients with an elevated ESR, an elevated WBC count, and or abnormal pelvic films suggestive of osteomyelitis, as well as in cases of stage 4 pressure injury with exposed bone. If osteomyelitis is confirmed, treatment with a prolonged course of antibiotic therapy may be indicated.


Histologic Findings

A concept that has been developed with regard to wound healing has to do with the presence of bacterial biofilms within a wound. Biofilms are structured communities of bacteria that may exist on a wound surface. A microscopic analysis of chronic wound specimens revealed the presence of densely aggregated bacterial colonies, often within their own extracellular matrix; however, these microscopic findings were not seen in acute wounds. [67]

Multiple in vivo studies have shown that wound healing is delayed when these biofilms are present in the wound. [68, 69] The biofilms seem to protect the underlying bacteria and provide resistance to antibiotic treatment and the body’s own immune system. Discussions among expert panels on wound healing have concluded that the most effective means of managing biofilms within wounds is to remove the biofilm; however, optimal methods of removal have yet to be clearly defined. [70]