Does a CT (Computed Tomography) pelvis need to be with or without contrast for a patient with Fournier's gangrene?

CT Pelvis for Fournier's Gangrene: Contrast-Enhanced Protocol

For patients with suspected Fournier's gangrene, CT pelvis should be performed WITH intravenous contrast 1.

Rationale for Contrast-Enhanced CT

Contrast-enhanced CT is specifically recommended by the World Journal of Emergency Surgery guidelines because it provides superior specificity for evaluating disease extent compared to non-contrast imaging and can identify the underlying source of infection 1. The contrast enhancement is critical for:

• Delineating fascial plane involvement and extent of necrosis, which directly impacts surgical debridement planning 1, 2
• Identifying abscesses and fluid collections that require drainage 3, 2
• Detecting the source of infection (colorectal pathology, urogenital source), which is a key mortality predictor 2
• Assessing retroperitoneal spread, as the disease can extend beyond the perineum 3

Diagnostic Performance

CT demonstrates excellent diagnostic accuracy with sensitivity approaching 90% and specificity of 93.3% for necrotizing soft tissue infections 1. Key CT findings include:

• Asymmetric fascial thickening 3, 2
• Subcutaneous emphysema (gas in soft tissues) - the hallmark finding, though present in only ~50% of cases 1, 3
• Soft tissue stranding and edema 2
• Fluid collections and abscess formation 3, 2

Critical Caveats: When NOT to Obtain CT

Imaging should NEVER delay surgical intervention 1. Specifically:

• In hemodynamically unstable patients despite adequate resuscitation, proceed directly to surgery without CT imaging 1
• In patients with obvious clinical findings of Fournier's gangrene (severe perineal pain, crepitus, systemic toxicity), do not delay surgery for imaging 1
• Imaging is not mandatory in emergent cases with clinical or hemodynamic impairment 1

Alternative When CT Not Feasible

If contrast-enhanced CT is contraindicated (acute renal failure) or the patient cannot be safely transported, bedside ultrasound is the preferred alternative 1. Ultrasound can demonstrate:

• Subcutaneous gas with high specificity (94%) 1, 4
• Marked scrotal skin thickening 1, 4
• Paratesticular fluid (appears before clinical crepitus) 1, 4
• Collections and abscesses 4

However, ultrasound lacks the comprehensive disease extent evaluation that contrast CT provides 1.

Practical Algorithm

1. Hemodynamically stable + equivocal clinical findings → Contrast-enhanced CT pelvis 1
2. Hemodynamically unstable OR obvious clinical diagnosis → Proceed directly to operating room 1
3. Stable but CT contraindicated/unavailable → Bedside ultrasound 1
4. Any imaging delay > 30-60 minutes → Abandon imaging and proceed to surgery 1

The mortality rate of Fournier's gangrene is 20-30%, and early aggressive surgical debridement improves survival 1, 5. Time to surgery is the most critical determinant of outcome, making the decision to image versus operate immediately the most important clinical judgment 1.