Primary vs secondary iliopsoas abscess. Presentation, microbiology, and treatment.

OBJECTIVE

To review the characteristics of patient presentation, microbiology, and treatment of primary iliopsoas abscess.

DESIGN

A case series of patients with iliopsoas abscess diagnosed on computed tomographic scans from 1987 to 1994.

SETTING

Tertiary care inner-city university hospital.

PATIENTS

Eleven patients with secondary iliopsoas abscess, defined as being secondary to gastrointestinal or genitourinary causes or trauma, and seven patients with primary abscess, defined as the absence of the above causes.

MAIN OUTCOME MEASURES

Patient characteristics, presenting symptoms and signs, microbiologic characteristics, treatment, and clinical course of patients with primary iliopsoas abscesses compared with those in patients with secondary abscesses.

RESULTS

In the primary group, six patients (86%) were intravenous drug users and four (57%) were positive for human immunodeficiency virus. Staphylococcus aureus grew from cultures from five of seven patients with primary abscesses, whereas secondary abscesses had enteric flora. The typical patient presentation included fever, with complaints of pain in the flank, hip, or abdomen. Comparison of abscess drainage options showed shorter hospitalizations for surgical drainage than for percutaneous drainage (15.9 vs 28.5 days; P < or = .01).

CONCLUSIONS

A patient who presents with pain in the flank, hip, or abdomen may have a primary iliopsoas abscess. Computed tomography is the standard method of diagnosis. Antibiotic regimens for patients with primary iliopsoas abscess should include coverage for S aureus, and patients with secondary abscesses should have antibiotic regimens tailored for enteric bacteria. Drainage of abscess is essential for appropriate treatment, and surgical drainage is superior to percutaneous drainage in achieving prompt recovery.