The condition is rare, most commonly presenting in males aged 50-70 years, and usually confined to certain patient subgroups 1,2.
Risk factors include 1,2:
- diabetes mellitus
- liver cirrhosis
- urinary retention (e.g. bladder obstruction, neurogenic bladder)
- indwelling catheterization
- immunocompromised state
- recent instrumentation to the urethra or prostate
Clinical features are non-specific, often with lower urinary tract signs, such as dysuria, lower abdominal or perineal pain, increased urinary frequency, and urinary urgency, and systemic features of infection, such as fever 1,2. Digital rectal examination is also non-specific, with potential findings being prostatic enlargement, fluctuance, and pain 1,2.
Emphysematous prostatitis is typically a complication of acute bacterial prostatitis, which itself is often a complication of urinary tract infections that ascend to the prostatic ducts 1-3. Causative pathogens are generally Gram negative organisms, such as Klebsiella pneumoniae (most common in one review 1), Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis 1-4.
The gas produced in emphysematous prostatitis may be produced via two mechanisms 1-4:
- necrotic infective tissues fermenting glucose into carbon dioxide
- gas-producing organisms
Features of emphysematous prostatitis are subtle on conventional radiography and may be difficult to differentiate from normal bowel gas 1-6. Typically, there will be globular regions of increased lucency in the area of the prostate, which is characteristically overlying the pubic rami 1-6.
Transrectal ultrasound may be useful in diagnosing emphysematous prostatitis, whereby the prostate will be diffusely hypoechogenic with acoustic gas shadows 1,3,6. However, it may be difficult to differentiate gas shadows from other causes of shadows, such as prostatic calcification 1.
CT is the most commonly utilized modality for diagnosing emphysematous prostatitis, and demonstrates collections of gas within the prostate parenchyma 1-6. Additionally, CT will also reveal features of concurrent acute prostatitis and prostatic abscess, which are both nearly always present 2.
Although less available than CT, MRI is also highly sensitive for demonstrating loculations of gas within prostatic parenchyma, and other concurrent pathologies 2,3.
Treatment and prognosis
Management is identical to that of prostatic abscess. Thus, percutaneous ultrasound-guided or CT-guided transperineal or transrectal drainage is often considered the first choice for therapy, with concurrent broad-spectrum antibiotic coverage 1,2.
The mortality rate of emphysematous prostatitis is 25%, higher than that of non-emphysematous prostatic abscess, and also higher than that of emphysematous pyelonephritis and emphysematous cystitis 1.
History and etymology
The first case was described by Albert J Mariani, an American urologist, and his colleagues in 1983 6.