Fournier-Gangrän
Fournier gangrene is necrotizing fasciitis of the perineum. It is a true urological emergency due to the high mortality rate but fortunately, the condition is rare. It is primarily a clinical diagnosis, and definitive treatment must not be delayed to perform imaging, which usually has an ancillary role .
Epidemiology
Fournier gangrene is typically seen in men with diabetes mellitus, aged 50-70 years, and only rarely in women.
Other predisposing factors include :
- obesity (BMI >30)
- end-stage renal and/or liver failure
- hypertension
- immunosuppression
- alcoholism
- smoking
- debility
Clinical presentation
- perineal/scrotal pain, swelling, redness
- crepitus from soft tissue gas (up to 65%)
- systemically unwell
- fever and leukocytosis
Pathology
The source of infection can usually be identified, most commonly anorectal (such as from a perianal fistula or abscess) and less commonly genitourinary or perineal trauma. Sometimes the cause is not found.
The infection is usually polymicrobial. The most common organisms cultured are E.coli, Klebsiella, Proteus, Staphylococcus, and Streptococcus.
It begins as cellulitis that causes an endarteritis with thrombosis followed by a necrotizing infection that spreads through the fascial planes. Initially, this is in the perianal and perineal regions, with later extension to the thighs and anterior abdominal wall. Importantly the testes are usually spared due to their different arterial supply from the aorta.
The organisms often produce gas, thus causing subcutaneous emphysema.
Radiographic features
The diagnosis is usually clinical. The role of imaging includes:
- diagnosis not established
- determine the extent of disease
- detect the underlying cause
Plain radiograph
Radiolucent soft-tissue gas may be seen in the region overlying the scrotum or perineum. Subcutaneous emphysema may extend from the scrotum and perineum to the inguinal regions, anterior abdominal wall, and thighs.
Ultrasound
- thickened scrotal wall
- often edematous, with linear hypoechoic fluid streaks interspersed
- echogenic gas foci in the scrotum are pathognomonic
- punctate, hyperechoic inclusions with posterior acoustic shadowing and reverberation artifacts
- lacking clear margins, the acoustic shadowing from gas is often described as "dirty"
- testes and epididymides spared (due to their separate blood supply)
- peritesticular fluid
- anechoic fluid collections common, represent reactive hydroceles
CT
- soft tissue stranding, fascial thickening
- soft tissue gas
- extent of disease may be assessed prior to surgery
- cause of infection may be apparent (e.g. perianal abscess, fistula)
Treatment and prognosis
It is considered a urological emergency with a poor prognosis due to its high mortality rate (ranging ~15-50% ). Imaging should be used judiciously, and must not allow the delay of potentially life-saving definitive treatment .
Management options include:
- immediate radical surgical debridement of necrotic tissue
- intravenous broad-spectrum antibiotics
- hyperbaric oxygen therapy
- testes replaced into the remaining scrotum or covered by skin graft (once infection settled)
History and etymology
It was first described by a French professor of dermatology at the University of Paris, and director of the renowned venereal Hospital of St Louis, Jean Alfred Fournier (1832-1914) in 1883. He noted a fulminating gangrenous infection of male genitalia in young healthy males without an obvious cause.
Differential diagnosis
The differential in the setting of acute scrotal pain includes:
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Assoziationen und Differentialdiagnosen zu Fournier-Gangrän:
