The potential gravity of post-operative vascular infection makes early diagnosis essential. We report a case where this diagnosis was made on CT findings alone, in the absence of any other signs of infection. Rapid intervention led to complete cure. Beyond the immediate post-operative period, the presence of gas on the CT scan is rare but pathognomonic in the absence of a cutaneous fistula. The presence of this sign is therefore sufficient to indicate that reintervention is mandatory.