Laboratory findings consistent with the diagnosis of epidural abscess include elevated inflammatory markers, abnormal platelet count, and presence of Staphylococcus aureus. Laboratory results, while helpful, are not diagnostic of epidural abscess. Laboratory findings should supplement clinical and imaging findings to aid in the diagnosis.^[1]

Laboratory findings consistent with the diagnosis of epidural abscess include elevated inflammatory markers, abnormal platelet count, and presence of foreign organisms within the abscess.

An elevated erythrocyte sedimentation rate is observed in about 2/3 of patients.^[1]

An elevated C-reactive protein level is present.

A marked leukocytosis is present in approximately 2/3 of patients.

Thrombocytosis may be present, particularly in children with epidural abscess.^[2] Thrombocytopenia may be present, particularly in adults.^[2]

Bacteremia is detected in about 60% of patients. On laboratory analysis, the following microorganisms are commonly observed:^[3][1][4]

• Staphylococcus aureus
• Escherichia coli
• Pseudomonas aeruginosa
• Peptostreptococci and other Gram-positive bacteria
• Anaerobic Gram-negative bacteria
  • Bacteroides
  • Prevotella
  • Porphyromonas

Once an abscess has been identified on the imaging studies, it is important to identify the responsible organism by studying different types of isolated materials, such as blood, material from the abscess and cerebrospinal fluid. The chance of finding the responsible organism in the abscess is 90%, in the blood 62%, and in the cerebrospinal fluid about 19%.^[5]