Silent Danger: Retroperitoneal Air as a Radiological Red Flag

Free retroperitoneal air due to perforation of the descending colon is a rare but life-threatening clinical entity. While colonic perforations are commonly associated with diverticulitis, malignancy, or fecal impaction, their isolated retroperitoneal manifestation is distinctly uncommon and sparsely documented in the literature. The descending colon, due to its secondary retroperitoneal anatomical location, may perforate without causing classical peritoneal signs, often delaying clinical recognition and surgical intervention [1]. Affected patients frequently present with nonspecific symptoms such as mild abdominal discomfort, subcutaneous emphysema, or even mediastinal air – findings that may only be revealed through advanced imaging [2]. Due to the subtle clinical presentation, diagnosis is challenging and often relies on repeat cross-sectional imaging. Computed tomography (CT) remains the gold standard modality, allowing for detection of retroperitoneal free air and associated findings like localized fat stranding or bowel wall thickening. Although the exact incidence of retroperitoneal colon perforation is unknown, it is considered exceptionally rare, with only isolated case reports described to date [3]. The overall mortality for colonic perforation is reported to be up to 17%, and delayed diagnosis in retroperitoneal cases may further worsen outcomes. This case highlights the importance of considering gastrointestinal perforation in elderly patients with atypical presentation and emphasizes the critical diagnostic role of CT, especially if clinical suspicion persists.