[Psoas abscess: diagnostic and therapeutic usefulness of echography and computerized tomography]

Psoas abscess (PA) is a clinically infrequent entity. The abscess may form spontaneously (primary PA) or as a complication of contiguous infection (secondary PA). The use of ultrasonography (US) and computerized tomography (CT) facilitates diagnosis and treatment of a disorder which previously required surgery.

Nineteen cases of PA diagnosed over the last 7 years were retrospectively studied. Confirmation of diagnosis was established by exteriorization of pus with US, CT or during surgery.

Three primary PA (16%) and 16 secondary PA (84%) were diagnosed. The foci of origin of the secondary PA were: urologic (50%), rachydeal (25%), gastrointestinal (12.5%) and iatrogenic lumbar infection (12.5%). The most frequent germs in the primary PA were: Staphylococcus aureus (67%) and in the secondary PA, enterobacteriae (50%). The diagnostic profitability of US was 41% (7/17) and for CT was 100% (15/15). Percutaneous drainage was performed in 9 patients which failed in 2 cases due to compactness of pus (22%) and in another 2 because of undiagnosed osteomyelitis (22%). Two patients (10%) with underlying disease died despite adequate medical-surgical treatment.

Psoas abscess were secondary in 84% of the patients studied with most being due to enterobacteriae. The diagnostic profitability of computerized tomography was greater than that of ultrasonography (100% vs 41%). Percutaneous drainage is a valid therapeutic alternative. Relapse observed in this study was due to previously undiagnosed osteomyelitis.