Emphysematous prostatitis

Emphysematous prostatitis refers to gas-forming infection of the prostate, nearly always occurring concurrently with prostatic abscess.

Epidemiology

The condition is rare, most commonly presenting in males aged 50-70 years and usually confined to certain patient subgroups .

Risk factors

Risk factors include :

• diabetes mellitus (most common)
• liver cirrhosis
• urinary retention (e.g. bladder obstruction, neurogenic bladder)
• indwelling catheterization
• immunocompromised state
• recent instrumentation to the urethra or prostate

Clinical presentation

Clinical features are non-specific, often with lower urinary tract signs (e.g. dysuria, lower abdominal/perineal pain, increased urinary frequency/urgency) and systemic features of infection (e.g. fever) . Digital rectal examination is also non-specific, with potential findings including prostatic enlargement, fluctuance, and pain .

Pathology

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 . Causative pathogens are generally Gram negative organisms, such as Klebsiella pneumoniae (most common in one review ), Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis .

The gas produced in emphysematous prostatitis may be produced via two mechanisms :

• necrotic infective tissues fermenting glucose into carbon dioxide
• gas-producing organisms

Radiographic features

Plain radiograph

Features of emphysematous prostatitis can be subtle on conventional radiography and may be difficult to differentiate from normal bowel gas . Typically, there will be globular regions of increased radiolucency in the area of the prostate, which is characteristically overlying the pubic rami .

Ultrasound

Transrectal ultrasound may be useful in diagnosing emphysematous prostatitis, whereby the prostate will be diffusely hypoechogenic with acoustic gas shadows . However, it may be difficult to differentiate gas shadows from other causes of shadows, such as prostatic calcification .

CT

CT is the most commonly utilized modality for diagnosing emphysematous prostatitis and demonstrates collections of gas within the prostate parenchyma . Additionally, CT will also reveal features of concurrent acute prostatitis and prostatic abscess, which are both nearly always present .

MRI

Although less available than CT, MRI is also highly sensitive for demonstrating loculations of gas within prostatic parenchyma and other concurrent pathologies as aforementioned .

Treatment and prognosis

As it nearly always occurs alongside prostatic abscess, 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 .

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 .

History and etymology

The first case was described by Albert J Mariani, an American urologist, and his colleagues in 1983 .