Fournier's gangrene

Fournier’s gangrene is a necrotizing fasciitis of the the perineum, penis, or scrotum with a prevelence of 1 in 7500 persons. Most infections are polymicrobial, although Group A streptococcus and staphlococcus has been implicated in several cases. The infected Dartos fascia overlies the scrotum and is continuous with Colles’ fascia of the perineum and Scarpa’s fascia of the abdominal wall. Infection can spread rapidly along these fascial planes leading to widespread tissue necrosis and sepsis. Involvement of the perineum and lower abdominal wall is often present at presentation. A source of infection is indentifiable in 95% of cases. The most common etiology is perianal infection due to inflammatory bowel disease, colonic diverticulitis, or as a complication of colorectal malignancy. Urogenital sources have also been implicated, such as urinary tract infections, bulbourethral gland infections, or iatrogenic urethral injuries. Direct perineal trauma is another rare, but reported cause of Fournier’s gangrene. Common comorbidities include conditions causing immunosuppression such as diabetes mellitus, malignancy, steroid use, morbid obesity, cirrhosis, and alcholism. Fournier’s gangrene can occur in any age group, and the typical presentation is fever and the rapid onset of pain and swelling in the involved area. Severe disease is marked by an increasing area of crepitation, extensive superficial erythema, and septic shock. Mortality is as high as 39% if diagnosis and prompt surgical debridement are delayed. Diagnosis is based on clinical examination, but it can be aided by ultrasonography, CT, or MR imaging. On ultrasound, thickened scrotal skin containing air, seen as hyperechoic foci, is highly suggestive of Fournier’s gangrene. CT can reveal the extent of soft tissue involvement more clearly, and etiologies such as incarcerated inguinal hernias, fistulas, or abscesses may be visualized. MRI allows for detailed assessment of the involved structures and can aid in planning surgical debridement.