Emphysematous Cystitis

Emphysematous cystitis is a rare complicated urinary tract infection in which gas forming organisms produce gas within the bladder wall and lumen. The organisms ferment glucose and produce carbon dioxide and hydrogen.

It affects older adults (mean age about 66 years) with a marked female predominance (about 2 to 3:1). Diabetes mellitus is present in about 50 to 67 percent, since glucose in the tissues acts as the substrate.

Causative organisms:

• Escherichia coli (about 60 percent)
• Klebsiella pneumoniae (about 10 to 20 percent)
• Proteus mirabilis, Enterobacter, Pseudomonas, Clostridium perfringens, Enterococcus, Streptococcus, Staphylococcus aureus, and Candida species

Other risk factors are bladder outlet obstruction (benign prostatic hyperplasia, neurogenic bladder), indwelling catheter, recurrent urinary tract infection, immunosuppression, and chronic kidney disease.

Mortality is about 7 to 10 percent overall. It is higher with sepsis, delayed treatment, or coexisting emphysematous pyelonephritis (found in 10 to 15 percent).

• Often non-specific: lower abdominal or suprapubic pain, fever, dysuria, frequency and haematuria.
• Pneumaturia (air in urine) in about 10 to 20 percent, with a palpable crepitus over the bladder in rare cases.
• Nausea, vomiting, abdominal distension and mental confusion in older diabetic patients.
• Sepsis with hypotension in severe disease; sometimes asymptomatic and found incidentally on imaging (about 7 percent).
• Poor glycaemic control: hyperglycaemia and ketoacidosis may accompany the infection.
• Examination: suprapubic tenderness; there may be urinary retention.

• Imaging confirms the diagnosis.
  • Plain abdominal X-ray: a crescentic or curvilinear outline of the bladder wall with gas.
  • Ultrasound: hyperechoic foci with dirty acoustic shadowing in the bladder wall.
  • CT is the most sensitive and specific. It shows gas in the bladder wall and lumen, and absence of gas in the upper tracts or with extension to the ureters, kidneys or perivesical tissues. It excludes enterovesical fistula and assesses emphysematous pyelonephritis.
• Urinalysis (pyuria, bacteriuria, haematuria) and urine culture (positive in about 90 percent), and blood cultures (positive in about 20 percent).
• Laboratory: complete blood count with leucocytosis, C-reactive protein, creatinine, blood glucose and HbA1c, and lactate for sepsis.
• Cystoscopy (cautiously) may show bullous mucosal lesions, but is generally unnecessary.
• Differential diagnosis: gas from instrumentation or catheterisation, enterovesical or vesicovaginal fistula, and pneumaturia from intestinal disease.

Prompt treatment with antibiotics, glycaemic control and bladder drainage is needed, and most patients respond to medical therapy.

• Empiric intravenous antibiotics, adjusted by culture. Options are:
  • a third generation cephalosporin (ceftriaxone 1 to 2 g daily)
  • piperacillin tazobactam 4.5 g every 6 to 8 hours
  • a carbapenem (meropenem 1 g every 8 hours) for severe disease or resistant organisms
  • a fluoroquinolone (ciprofloxacin 400 mg intravenously every 12 hours)
• Add an aminoglycoside if needed (gentamicin 5 mg/kg daily, adjusted to renal function). Cover Pseudomonas and ESBL-producing organisms according to local resistance.
• Add fluconazole 400 mg daily or an echinocandin (caspofungin 70 mg loading dose, then 50 mg daily) if Candida is found.
• Duration is 7 to 14 days, intravenous at first, then oral step down therapy when improved (total of 14 days for complicated infection).
• Strict glycaemic control with insulin infusion or basal bolus insulin (target glucose 140 to 180 mg/dL in the acute illness), and correction of dehydration and electrolytes.
• Bladder drainage: indwelling urethral catheter (18 to 20 Fr) for 7 to 14 days, or suprapubic catheter, to relieve obstruction and monitor urine output.
• Treat the underlying obstruction (alpha blocker, transurethral resection of prostate after infection control, clean intermittent catheterisation).
• Sepsis management: fluid resuscitation, vasopressors, early antibiotics within 1 hour, and monitoring.
• Surgical intervention is required in the minority with failure of medical therapy, necrotising infection, bladder rupture, or perforation. Options are debridement, partial cystectomy or cystectomy.
• Treat associated emphysematous pyelonephritis with percutaneous drainage or nephrectomy.
• Follow up imaging (CT or ultrasound) at 1 to 2 weeks to confirm resolution of gas. Repeat urine culture 1 to 2 weeks after treatment. Evaluate the cause (urodynamics, cystoscopy, voiding evaluation).
• Prevention: tight glycaemic control, treatment of bladder outlet obstruction, avoidance of long term catheters, and treatment of recurrent urinary infection.
• Prognosis is good with early treatment (90 percent survival). It is worse with delayed diagnosis, sepsis, or coexisting upper tract involvement.