Objective: Iliopsoas abscess (IPA) is a rare condition, with little evidence based knowledge to guide the physician in the management of the patient. This paper presents a review of the literature, and a material of eight patients with IPA is described. The current knowledge about the epidemiology, etiology, diagnosis, treatment and prognosis is presented.
Method: Literature was obtained searching PubMed in January and February 2008. Search was made without time limitation, using the key words “psoas abscess OR iliopsoas abscess”. With limitation to English language this search gave 655 hits, of which 45 were review articles. References were chosen based on subjective consideration of their relevance for this article’s objective. Special emphasis is given to nine relatively recent case series published between 1990 and 2007, which altogether describe 171 cases of IPA. This article also presents eight cases of IPA from Ullevål University Hospital (UUS). All patients were treated between 2001 and 2005. The material has been collected retrospectively, with the help of physicians on various wards. It is possible that also other patients have been treated for the same condition during the same period of time.
Results: Epidemiology: there is little knowledge about the incidence of IPA, but there is general agreement that it has decreased as a consequence of the decreased prevalence of tuberculosis, since tuberculosis of the spine was previously the main cause of secondary IPA. It is suggested in literature that we are now seeing an increasing incidence in industrialized countries because of immigration, and possibly because more people live with immunosuppression. Etiology: around 68% of IPA are secondary to the spread of an infection in adjacent tissues, while 32% have no known infectious origin and are considered primary. The causes of secondary IPA are Crohn’s disease (16%), abdominal and gastrointestinal conditions excluding Crohn (18%), post operative infections (11%), spondylodiscitis excluding TB (16%), TB spondylodiscitis (3%), urinary or gynaecological conditions (20%), non-spinal osteomyelitis (5%), trauma (3%). Primary IPA are most commonly caused by S. aureus. Secondary infections have a more mixed list of causative organisms. Diagnosis: clinical presentation is often vague and non-specific. Diagnosis is best made with a CT-scan of the abdomen. Treatment: recent studies have shown good results for CT-guided percutaneous drainage in combination with antimicrobial treatment. Other treatment options include open, surgical drainage, conservative treatment with antimicrobials alone and percutaneous needle aspiration without any further drainage. Prognosis: little data about this. Estimates suggest low mortality for primary IPA, and higher rates for secondary IPA.
Conclusion More knowledge is needed before a protocol for management can be made. Questions that remain unanswered are: for how long should antimicrobial treatment be given? Which patients benefit from percutaneous drainage and who need an open, surgical drainage? For how long should a percutaneous drainage last?