To study the variations of aetiology in the patients with acute pyogenic iliopsoas abscess and identify the appropriate diagnostic modalities as well as therapeutic alternatives (e.g. extraperitoneal or retrofascial percutaneous catheter drainage, PCD) other than surgery. We carried out a retrospective review and analysis of 25 patients with acute pyogenic iliopsoas abscess in our institution from August 1988 to July 1998. Blood and urine cultures, imaging studies of the plain films of the abdomen (KUB), ultrasonography (echo) and computed tomography (CT scan) were performed in all patients. The therapeutic regimens included antibiotics only, PCD or aspiration, and surgery. The male to female ratio was 7: 18. The mean age was 64 years old. Diabetes mellitus (64%) was the dominant predisposing or associated factor. The most common aetiological source was urinary tract infection (52%) with enteric micro-organisms (Escherichia coli: 44% and Klebsiella spp.: 24%). Nineteen patients (76%) had pain in the abdomen, flank or back. Six cases (24%) were classified as 'primary' abscess, and only two patients survived. Nine cases were treated with antibiotics alone, only four responded and the others expired. Of the 15 cases receiving PCD or aspiration, five cases received subsequent surgical drainage or nephrectomy and survived. Another one case of Clostridia gas gangrene received emergency fasciotomy and expired. The total mortality was extremely high (11/25, 44%). We concluded that: (i) the aetiology of iliopsoas abscess may vary with the country of origin, with a preponderance of urinary tract infection in our Taiwanese series; (ii) a high index of suspicion is mandatory to enable early diagnosis of acute pyogenic iliopsoas abscess, particularly for older diabetic patients with fever, pain in the abdomen or flank, limp or flexion of the ipsilateral hip; (iii) CT scan can confirm the diagnosis and define the extent of the abscess; (iv) effective management should include appropriate antibiotic therapy and drainage of the abscess; (v) image-guided PCD should be tried first because of its low morbidity. However, should it fail, subsequent surgical drainage should be performed.
