A rare case of iliopsoas abscess caused by a retained shrapnel from a blast injury

Background

Iliopsoas abscess (IPA) is an uncommon and often misdiagnosed condition with non-specific symptomology. Its classic triad of back pain, fever and a limp is rarely seen. Because of this, treatment is often delayed, and subsequent mortality can be as high as 20%.1 2 Our report illustrates an uncommon cause for this condition and highlights the importance of definitive surgical management in patients with sepsis associated with IPA.

Case presentation

We describe the case of a 55-year-old man war veteran who presented with an unusual cause of IPA secondary to retained foreign body (FB).

The patient presented with 1 week of fever and back pain, and reported this to be his third similar presentation in 3 years. His initial trauma 30 years before was a result of a blast injury with shrapnel penetration suffered after inadvertently driving over a landmine as an ambulance driver in a conflict region. The injuries required management with trauma laparotomy and extensive bowel resection at the time of the trauma. He had no other medical comorbidities and was not an intravenous drug user. He reports having had two episodes of IPA in 2018 and 2019 prior to the reported index presentation. Ultrasound scans undertaken at these preceding presentations demonstrated shrapnel debris within the psoas with surrounding abscess collection. The management then included antibiotics and radiologically guided drainage of the abscess; it is unclear why surgical exploration was not undertaken at these times.

Investigations

Examination on presentation demonstrated an ataxic gait and renal angle tenderness. The patient was febrile at 38.3°C and tachycardic. Bloods revealed leucocytosis of 13.7×10⁹ /L and a C reactive protein of 111 mg/L. A CT scan was performed, revealing a 13 mmx8 mm radio-opaque FB within the right psoas at the level of the fifth lumbar vertebra with a surrounding collection (figure 1). A diagnosis of FB-induced IPA was made, and the patient was promptly given ceftriaxone and metronidazole.

Figure 1

CT on admission showing right sided foreign body (yellow arrow) embedded within the iliopsoas and surrounding abscess collection and fat stranding.

Treatment

Work-up for surgical debridement was made with a CT guide-wire insertion, lateral and superior to the iliac crest (figure 2); in the process, two smaller FB were seen superficially. Subsequent open surgical exploration removed two gravel fragments (figure 3). A large abscess cavity was subsequently drained with the fluid sent for appropriate culture and analysis. The third and most superficial FB was not located but was felt to likely extirpate independently postoperatively given the open nature of the surgical wound at completion. A corrugated drain was inserted, with alginate dressings applied in the wound. The patient tolerated the procedure well was discharged 2 days later with a course of oral cefalexin and daily dressing change.

Figure 2

CT guided guide-wire insertion revealing three foreign bodies.

Figure 3

Largest gravel from iliopsoas removed intraoperatively measuring 15 mm.

Outcome and follow-up

Home visits by nursing staff occurred over a week for management of the corrugated drain, which was removed given negligible output. Wound care continued for further 3 weeks with alginate dressings allowing for healing by secondary intention. No complications were demonstrated in his follow-up a month post admission. The patient remained well in his community; and in his final follow-up 6 months beyond his index presentation, the wound had completely healed.