An unusual case of an extensive post-injection retroperitoneal abscess in an intravenous drug user.

Retroperitoneal abscesses constitute an uncommon, complex, and life-threatening intra-abdominal infection. The insidious nature of the presentation, coupled with the presence of non-specific clinical symptoms, might result in misdiagnosis or delayed diagnosis, ultimately contributing to substantial morbidity and mortality. Herein we report a case of a 32-year-old intravenous drug user who presented to the emergency department complaining of high-grade fever, intense hiccough, and back pain due to retroperitoneal abscess formation after intravenous injection in the left femoral vein.