Necrotising fasciitis of the perineum and scrotum: gas in the scrotal wall and perineal fascia spreading to the abdominal wall — CT maps the extent and finds the source (perianal abscess, urethral injury) for debridement.
Orient first
- Infection spreads along Colles fascia to the scrotum and penis, along Scarpa fascia to the abdominal wall, and into the ischiorectal fossae.
- The testes are usually spared (separate blood supply) — scrotal wall gas with normal testes is typical.
- Sources: anorectal (perianal abscess), urogenital (stricture, catheter trauma), skin.
Acquire the study
- Portal venous phase CT from the diaphragm to the upper thighs; lung window for gas, coronal reformats.
The manoeuvre
- Lung window: gas in the scrotal wall, perineum, ischiorectal fossae and the anterior abdominal wall; state the most cranial level.
- Soft-tissue window: fascial thickening and fluid; retroperitoneal extension along the psoas.
- Source: perianal or ischiorectal abscess, a fistula, a urethral or bladder cause.
What confirms it
- Subcutaneous or fascial gas in the scrotum or perineum with a septic patient.
What licenses you to exclude it
- Absence of gas does not exclude Fournier gangrene; surgical assessment decides.
The classic misread
- Missing retroperitoneal extension because the scan stopped at the pubis.