CT imaging plays a critical role in diagnosing and evaluating the extent of Fournier’s gangrene, offering superior diagnostic capabilities compared to plain radiographs and ultrasound. It is particularly helpful in confirming the diagnosis in unclear cases and in identifying the underlying source of infection. For optimal assessment, the CT scan should cover the abdomen, pelvis, perineum, and scrotum, ensuring a comprehensive evaluation of both the disease’s spread and origin. Limiting the scan to only the pelvis may miss abdominal sources, so intravenous contrast material is recommended unless contraindicated.

Typical CT findings include asymmetric fascial and skin thickening, fat stranding, and soft tissue changes. The infection can spread along Colles and Dartos fascia from the perineum to involve the scrotum and penis, with gas accumulation often signifying gas-forming bacteria.[fig]2 This gas can dissect along superficial and deep fascial planes, potentially reaching areas such as the abdominal wall, inguinal regions, or even the chest in severe cases. In situations involving abdominal pathology, laparotomy may be necessary, and recognizing retroperitoneal extension is crucial for surgical planning.

CT scans are invaluable for distinguishing Fournier’s gangrene from less aggressive conditions like cellulitis, as they provide detailed imaging of both superficial and deep fascia. Additionally, CT can help identify underlying causes, including perianal abscesses, diverticulitis, and colorectal perforation. In cases of colonic perforation, CT not only detects extraluminal gas but also shows the extravasation of contrast material, aiding diagnosis.

Fournier gangrene can also occur as a complication of hernia repair, scrotal surgery, or gender reassignment surgery. In female patients, although the typical CT findings are similar to those in males, the infection often spreads more quickly to the abdominal and retroperitoneal spaces (seen in less than 20% of their male counterparts), due to differences in pelvic anatomy (a rich lymphatic network that helps spread the infection). For this reason, comprehensive CT imaging of the abdomen and pelvis is essential in females to assess any disease extension beyond the pelvis.

CT is highly sensitive and specific for detecting abnormal gas collections, characteristic of Fournier’s gangrene, though about 10% of cases may lack subcutaneous emphysema. CT can detect subcutaneous emphysema even before it becomes clinically visible. The extent of fascial thickening and fat stranding observed on CT correlates well with the tissue affected during surgery, helping to plan the surgical approach. Contrast-enhanced CT further differentiates necrotic from viable tissue, enabling earlier diagnosis before clinical symptoms appear, which is crucial for surgical planning. Follow-up CT scans are also essential for monitoring disease progression, guiding whether further intervention or surgery is necessary.

The following sequence of images visually summarizes the key findings of this study (from [fig]3 to [fig]10).