A 38 year old woman was admitted as an emergency with acute on chronic lower back pain. Examination revealed a fixed flexion deformity of the left hip, but no neurological deficit. She had lost 11 kg in weight over the preceding two months, and had recently had investigations for iron deficiency anaemia. Endoscopy showed that she had an oesophageal web, but no inflammation or bleeding to account for the anaemia. She was treated with fluconazole for cundidu, which had been identified in the oesophagus and was prescribed ferrous sulphate.Initial investigations revealed a hypochromic microcytic anaemia of 7.2 g &-' and an elevated white cell count of 15.6 x lo9 L-' (neutrophilia). The erythrocyte sedimentation rate was elevated at 94 mm h-' and her Creactive protein 285 mg L-' (normal range 1-10 mg L-'). Serum B12, folate and red cell folate were normal as were urea, electrolytes and CA125. She was negative for human immunodeficiency virus; early morning urine and sputum samples were negative for tuberculosis. Lumbar spine and pelvic radiographs revealed no significant abnormality. On isotope bone scan a right hydronephrosis and hydroureter were seen, although no focus of increased bone scintigraphic activity was apparent. An ultrasound examination revealed not only bilateral hydronephrosis but also an elongated hypoechoic lesion inferior to the left kidney within the retroperitoneum. A psoas collection was suspected and confirmed by computed tomography. A computed tomography guided drainage procedure was undertaken. Thick pus was aspirated and sent for culture. A J-guide wire was passed into the psoas collection. The tract was dilated using 8 and 9 F dilators and an 8.4 F pigtail drain was passed and sutured to the skin.An intravenous urogram examination demonstrated partial obstruction at the lower end of the right ureter. On the left side there was only a faint nephrogram and no contrast was seen in the collecting system 18 hours post injection. A left antegrade pyelogram was performed Culture of the psoas muscle aspirate subsequently grew both Actinomyces sp. and Prevatella bivia. Therapy was commenced with a three month course of metronidazole (500 mg three times daily, intravenously, for five days then 400mg three times daily by mouth) and augmentin (1.2 g three times daily for five days then 625 mg three times daily by mouth) on the advice of the hospital microbiology department. The suspicion that her infection might be related to an intrauterine contraceptive device (IUCD) was raised. She had been using an IUCD as contraception for 10 years and although it had been changed 18 months previously, she had been troubled with a brownish discharge since. The current IUCD was copper, but the nature of the previous IUCD was not determined.A transvaginal ultrasound examination revealed bilateral cystic adnexal masses suggestive of hydro-or pyosalpinx. Curettage, cystoscopy and laparoscopy were performed under general anaesthesia. High vaginal and endocervical swabs were obtained, and a CU375 (multiload) IUCD was re...